A&P EXAM 5 REVIEW GUIDE. 2023

docx

School

Upper Cape Cod Regional Technical School *

*We aren’t endorsed by this school

Course

PN 103

Subject

Anatomy

Date

Jan 9, 2024

Type

docx

Pages

31

Uploaded by MinisterWillpower16892

Report
PN 103 Anatomy and Physiology Fall 2023 / SCHMITT Exam #5 Study Guide Chapter 21 Digestive System Explain mechanical, chemical digestion Mechanical digestion : This is the first phase of digestion. It involves physically breaking down food into smaller pieces, beginning with chewing in the mouth and continuing with contractions and churning in the stomach and small intestine. Chemical digestion : The second phase of digestion uses digestive enzymes produced in the salivary glands, stomach, pancreas, and small intestines to break down food particles into nutrients (such as glucose, amino acids, and fatty acids) that cells can use. Describe the location and function of organs of the digestive system The digestive tract includes the: Mouth : The mouth is also called the oral, or buccal, cavity. It’s surrounded by lips and bordered on each side by the cheeks. The palate forms the roof of the mouth and the tongue and its muscles form the floor. The mouth is the entryway to the digestive tract; it’s also where digestion begins. Pharynx : After food leaves the oral cavity, it moves into the pharynx. Esophagus : Connecting the pharynx to the stomach is the esophagus: a muscular tube about 10 inches (25 cm) long. Glands within the wall of the esophagus secrete mucus that helps lubricate the food bolus as it passes through. When a bolus enters the esophagus, it triggers wave-like muscular contractions (peristalsis) that propel the food toward the stomach. Stomach : Just below the diaphragm, the digestive tube expands to form the stomach, a muscular sac whose primary function is to store food. The stomach also prepares food for digestion. Specifically, the muscles of the stomach contract and churn to break food into small particles and to mix it with gastric juice. What results is a semifluid mixture called chyme. Chyme leaves the stomach and enters the duodenum by passing through the pyloric sphincter. Large intestine : Once the food has been processed and its nutrients absorbed, the remaining residue is ready to leave the small intestine for the large intestine. In fact, about 500 ml of residue—consisting of undigested food, sloughed off epithelial cells, minerals, salts, and bacteria—enter the large intestine each day. The large intestine absorbs large amounts of water from the residue before passing the resulting waste material (feces) out of the body. The large intestine begins in a blind pouch called the cecum. Attached to the lower end of the cecum is a tubular organ called the appendix. The appendix contains masses of lymphoid tissue and serves as a source for immune cells. At the point where the ileum meets the large intestine is the ileocecal valve, which helps ensure that material moves in a forward direction only. The ascending colon extends up toward the liver. The colon makes a sharp turn at the
right colic (hepatic) flexure. The transverse colon passes below the liver, stomach, and spleen. The colon turns sharply downward at the left colic (splenic) flexure. The descending colon extends downward along the left side of the abdominal cavity. The sigmoid colon forms an S shape down to the rectum. Small intestine : Most chemical digestion, and most nutrient absorption, occurs in the small intestine. Filling most of the abdominal cavity below the stomach, and held in place by mesentery, the small intestine consists of three divisions: the duodenum, the jejunum, and the ilium. The duodenum is the first 10 inches (25 cm) of small intestine. It begins at the pyloric valve and ends as the intestine turns abruptly downward. The duodenum receives chyme from the stomach as well as pancreatic juice and bile. This is where stomach acid is neutralized and pancreatic enzymes begin the task of chemical digestion. More digestive processes occur here than in any other part of the intestine. The jejunum constitutes the next 8 feet (2.4 m) of small intestine. Many large, closely spaced folds and millions of microscopic projections give the jejunum an enormous surface area, making it an ideal location for nutrient absorption. The wall of the jejunum is thick and muscular with a rich blood supply, which imparts a red color to this part of the intestine. The ileum is the last 12 feet (3.6 m) of intestine. The wall of the ileum is thinner and has less blood supply than does the wall of the jejunum. Clusters of lymphatic nodules called Peyer’s patches are scattered throughout the ileum. Rectum : The rectum is the last 7 to 8 inches (17 to 20 cm) of intestine. The mucosa of the rectum forms longitudinal folds called anal columns. Anus : The anal canal, which makes up the last inch (2.5 cm) of the rectum, opens to the exterior through the anus. The anus contains two sphincters: an internal sphincter (composed of involuntary smooth muscle) and an external sphincter (composed of voluntary skeletal muscle). The accessory organs include the: Teeth : Digestion begins when food enters the mouth and is chewed: a process called mastication. Besides breaking food into pieces small enough to be swallowed, chewing allows food to become moistened with saliva. The adult mouth contains 32 permanent teeth designed to cut, tear, and grind food. Tongue : The tongue is a skeletal muscle covered by a mucous membrane. It repositions food in the mouth during chewing; it also contains taste buds within projections called lingual papillae. Salivary glands : Salivary glands secrete saliva, a clear fluid consisting mostly of water, but also containing mucus, an enzyme that kills bacteria, antibacterial compounds, electrolytes, and two digestive enzymes. The mouth also contains minor salivary glands in the tongue, inside the lips, and on the inside of the cheeks. The parotid gland lies just underneath the skin anterior to the ear. Its duct drains saliva to an area near the second upper molar. The mumps virus causes swelling and inflammation of the parotid gland. The submandibular gland empties into the mouth on either side of the lingual frenulum. The sublingual gland drains through multiple ducts onto the floor of the mouth. Enzymes contained in saliva begin the digestion process:
amylase breaks down starch while lipase begins the digestion of fat. Liver : The body’s largest gland, the liver fills the upper right abdomen below the diaphragm. Even more impressive than its size is its function: the liver performs more than 250 tasks, including storing and releasing glucose, processing vitamins and minerals, filtering toxins, and recycling old blood cells. Nutrient-rich blood from the stomach and intestine enters the lobule through small branches of the portal vein. Oxygen-rich blood enters the lobule through small branches of the hepatic artery. The blood filters through the sinusoids, allowing the cells to remove nutrients (such as glucose, amino acids, iron, and vitamins) as well as hormones, toxins, and drugs. At the same time, the liver secretes substances—such as clotting factors, albumin, angiotensinogen, and glucose—into the blood for distribution throughout the body. Also, phagocytic cells called Kupffer cells remove bacteria, worn-out red blood cells, and debris from the bloodstream. The central vein carries the processed blood out of the liver. Canaliculi carry bile secreted by hepatic cells and ultimately drain into the right and left hepatic ducts. Each day, the liver secretes up to 1 liter of bile: a yellow- green fluid containing minerals, phospholipids, bile salts, bile pigments, and cholesterol. The main bile pigment is bilirubin, which results from the breakdown of hemoglobin. However, the most important component of bile is bile salts. Formed in the liver from cholesterol, bile salts aid in the digestion and absorption of fat in the small intestine. After secretion, 80% of bile salts are reabsorbed in the final section of the small intestine (the ileum). It is then returned to the liver, where hepatocytes absorb and then secrete the bile once again. The 20% of bile not reabsorbed is excreted in feces. Pancreas : The pancreas lies behind the stomach; its head is nestled in the curve of the duodenum and its tapered tail sits below the spleen and above the left kidney. The pancreas is both an endocrine and exocrine gland. Its endocrine function centers on pancreatic islets that secrete insulin and glucagon. Most of the pancreas, though, consists of exocrine tissue. Each day, the pancreas secretes about 1.5 liters of pancreatic juice—essentially digestive enzymes and an alkaline fluid—into the small intestine. Acinar cells secrete digestive enzymes in an inactive form; once activated in the duodenum, the enzymes help break down lipids, proteins, and carbohydrates. Epithelial cells in pancreatic ducts secrete sodium bicarbonate, which buffers the highly acidic chyme entering the duodenum from the stomach. Gallbladder : A sac attached to the underside of the liver, the gallbladder stores and concentrates bile. The gallbladder is about 3 to 4 inches (7–10 cm) long and holds 30 to 50 ml of bile. The bile duct merges with the duct of the pancreas to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla enters the duodenum at a raised area called the major duodenal papilla. A sphincter called the hepatopancreatic sphincter (sphincter of Oddi) controls the flow of bile and pancreatic juice into the duodenum. Explain the function of saliva Saliva moistens the mouth and lubricates and protects the teeth. It also plays an important role in taste. One of its main roles, though, is to moisten food and transform it into a mass called a bolus that can be swallowed easily. Enzymes contained in saliva begin the digestion process: amylase breaks down starch while lipase begins the
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
digestion of fat. Salivary glands secrete about 1 liter of saliva daily. The pressure and taste of food in the mouth stimulates the secretion of saliva. The smell or sight of food —or even just the thought of food—also stimulates salivation. On the other hand, stimulation of the sympathetic nervous system, such as through fear, inhibits the secretion of saliva, causing the mouth to feel dry. Salivary glands secrete saliva, a clear fluid consisting mostly of water, but also containing mucus, an enzyme that kills bacteria, antibacterial compounds, electrolytes, and two digestive enzymes. Describe the role of secretory cells in the stomach and intestines Stomach: The gastric mucosa contains depressions called gastric pits. Several different glands (called gastric glands) open into the bottom of each gastric pit. These glands secrete the various components of gastric juice. Mucous cells secrete mucus, which protects the stomach lining and keeps the stomach from digesting itself. Parietal cells secrete hydrochloric acid and intrinsic factor (which is necessary for the absorption of vitamin B12). Hydrochloric acid helps kill microbes in swallowed food. Chief cells secrete digestive enzymes, such as pepsinogen. Enteroendocrine cells secrete the hormone ghrelin (which stimulates the hypothalamus to increase appetite) and gastrin (which influences digestive function). Intestines: The intestinal lining contains circular folds that slow the progress of chyme and increase its contact with the mucosa. On top of the circular folds are projections called villi (singular: villus). An arteriole, a venule, and a lymph vessel called a lacteal fill the core of each villus. Covering the villi are absorptive epithelial cells as well as mucus- secreting goblet cells. The mucus, after being secreted by the goblet cells, expands to create a dense layer attached to the epithelium that is impenetrable to bacteria. Epithelial cells covering the villi have a brush border of ultrafine microvilli. Besides further increasing the absorptive area, the microvilli produce digestive enzymes. Pores at the bases of the villi, called intestinal crypts, contain goblet cells that secrete mucus that helps the passage of food. They also serve as sites for rapid cellular growth, producing new cells to replace those shed from the villi. Describe the role of the large intestines Once the food has been processed and its nutrients absorbed, the remaining residue is ready to leave the small intestine for the large intestine. In fact, about 500 ml of residue—consisting of undigested food, sloughed off epithelial cells, minerals, salts, and bacteria—enter the large intestine each day. The large intestine absorbs large amounts of water from the residue before passing the resulting waste material (feces) out of the body. Identify the key digestive enzymes and the substances digested Salivary glands: Amylase - Starch Lipase - Fat
Stomach : Pepsin - Protein Pancreas : Proteases (trypsin, chymotrypsin) - Protein Lipase - Fats Amylase - Starch Intestine : Peptidases - Peptides Sucrase – Sucrose (Cane Sugar) Lactase – Lactose (Milk Sugar) Maltase – Maltose (Malt Sugar) Chapter 22 Nutrition and Metabolism Describe units of energy Energy expenditure is measured by the output of heat from the body. In nutrition, the unit of heat often used is the calorie: the amount of heat (or energy) needed to raise the temperature of 1 gram of water by 1 degree Celsius. In other words, calories are energy that the body uses as fuel. Name the three macronutrients Because the body requires fairly large amounts of carbohydrates, lipids, proteins, and water, these are called macronutrients. Briefly describe the metabolism of carbohydrates, lipids, and proteins Carbohydrates: Carbohydrates are the body’s primary energy source. We obtain carbohydrates by eating foods (particularly plants) that contain them. In plants, carbohydrates result from photosynthesis: the process by which plants use energy from sunlight to take up carbon dioxide and release oxygen. In essence, the carbohydrates in plants represent stored energy. By consuming carbohydrates, the body has access to that energy. Dietary carbohydrates occur in three forms: monosaccharides, disaccharides, and polysaccharides. Monosaccharides: Known as simple sugars - Taste sweet; Absorbed through the small intestine without being broken down Disaccharides: Also called simple sugars - Broken down into monosaccharides during the digestive process Polysaccharides: Known as complex carbohydrates; Consist of the starches found in vegetables, grains, potatoes, rice, and legumes; Includes cellulose as an important polysaccharide After consumption, gut bacteria ferment indigestible fibers, which results in the production of short-chain fatty acids (SCFA) and gases. Gas is expelled as flatus. Fiber also absorbs water in the intestines and swells. This adds bulk to the stool, which stretches the colon and increases peristalsis. In turn, this allows stool to pass more
quickly out of the body. All ingested carbohydrates are converted to glucose, most of which is immediately burned as energy. If the body doesn’t need the glucose for immediate energy, it stores it as glycogen or converts it to lipids. The primary goal of glucose catabolism is to generate adenosine triphosphate (ATP), which cells use for energy. This crucial task occurs in three distinct phases: glycolysis, anaerobic fermentation, and aerobic respiration. Lipids: Lipids, or fats, act as a reservoir of excess energy. Specifically, excess carbohydrates are converted to fat. Then, during periods of decreased food intake, fat reserves can be mobilized and broken down to release energy. Fat is an ideal substance for storing energy: not only is it more compact than carbohydrates, it’s also more energy dense. Each gram of fat contains 9 calories per gram, compared to 4 calories for each gram of carbohydrate. Fat fulfills other key roles in the body as well. For example: Fat enables absorption of certain vitamins. Vitamins A, D, E, and K are fat-soluble, meaning that they depend on dietary fat to be absorbed by the intestine. Fat contributes to cellular structure. Dietary fats can be converted to other lipids (such as phospholipids and cholesterol), which are major structural components of cell membranes and myelin. Cholesterol also acts as a precursor to steroid hormones, bile acids, and vitamin D. Fat insulates and protects the body. Besides insulating the body to conserve heat, fat also surrounds delicate internal organs to protect them from damage. The body can synthesize most of the fatty acids it needs. However, there are a few (such as linolenic acid, which is a necessary part of the cell membrane) it cannot synthesize. Called essential fatty acids, these fats must be obtained through the diet. They are found in such foods as vegetable oils, whole grains, and vegetables. Proteins: Proteins fulfill a vast array of functions in the body. For example, proteins are a major component of all cellular membranes. In addition, they make up much of the structure of bone, cartilage, tendons, ligaments, skin, hair, and nails. Antibodies, hormones, and hemoglobin—as well as about 2000 different enzymes—also consist of proteins. In fact, about 12% to 15% of the body’s mass is made of protein. The body contains more than 100,000 different proteins. Each of these proteins consists of various combinations of just 20 different amino acids. During the process of digestion, proteins are broken down into their individual amino acids. Once absorbed, the body recombines the amino acids to create a new protein for a specific purpose. Foods that supply all the essential amino acids are called complete proteins. Foods that lack one or more essential amino acids are called incomplete proteins. Nutritionists once thought that, for the body to create new proteins, all amino acids needed to be present simultaneously. In other words, they felt it was necessary to consume all 9 essential amino acids at each meal. Recent studies have shown, however, that the body can combine complementary proteins that are consumed over the course of a day. Complete proteins: Mainly come from animal sources; Include meat, fish, eggs, and dairy; Also include quinoa and soy
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Incomplete proteins: Come from plant sources; Include nuts, grains, and legumes Whereas carbohydrates and fat are mainly used to supply energy, proteins are primarily used to build tissue. Protein anabolism plays a significant role in the growth and maintenance of the body: new proteins are used to repair tissue, replace worn-out cells (including red blood cells), create enzymes, grow muscle, and synthesize antibodies, among many other things. Explain thermoregulation A key factor in homeostasis is the maintenance of body temperature within a narrow range. For this to occur, heat production must balance heat loss. This is known as thermoregulation. Normal body temperature is not static. Rather, it fluctuates about 1.8° F (1° C) through the course of a day, being lowest in the early morning and highest in the late afternoon. Body temperature also varies from one region of the body to another. To balance the production of heat, the body loses heat by three means: radiation, conduction, and evaporation. Radiation involves the transfer of heat through the air by electromagnetic heat waves. Conduction involves the transfer of heat between two materials that touch each other. In other words, heat passes out of our bodies and into objects that we touch, such as our clothes. Evaporation requires heat to change water into a gas. That’s why perspiration can effectively cool the body. Sweat causes the skin to become wet; then, as evaporation occurs, heat is drawn from the body. The hypothalamus acts as the body’s thermostat: it monitors the temperature of the blood and sends signals to blood vessels and sweat glands. When the body temperature rises too high, the hypothalamus signals cutaneous blood vessels to dilate. More warm blood flows close to the body’s surface, and heat is lost through the skin. If the temperature remains high, sweat glands produce sweat, and the evaporation of sweat produces cooling. When the body temperature falls below normal, the hypothalamus signals cutaneous blood vessels to constrict. Instead of flowing to the skin, warm blood remains confined deep in the body. As a result, less heat is lost through the skin. If the temperature remains below normal, the body begins to shiver. Muscle contractions associated with shivering release heat and raise the body’s temperature. Explain the term fever Fever is when the body temperature is higher than normal Discuss the factors that affect a person’s metabolic rate Metabolism involves two processes: Catabolism: Used in the metabolism of carbohydrates and lipids, this process breaks down complex substances into simpler ones or into energy. Anabolism: Used in protein metabolism, this process forms complex substances out of simpler ones.
Chapter 19 Urinary System Identify the location and function of each organ involved with the urinary system Kidneys: The kidneys lie against the posterior abdominal wall and underneath the 12th rib. They are also retroperitoneal, meaning that they are posterior to the parietal peritoneum. The ribs offer some protection to the kidneys, as does a heavy cushion of fat encasing each organ. Each kidney measures about 4 inches (10 cm) long, 2 inches (5 cm) wide, and 1 inch (2.5 cm) thick; they extend from the level of the T12 vertebra to the L3 vertebra. Structures (such as blood vessels, the ureters, and nerves) enter and leave the kidney through a slit called the hilum—located in a concave notch on the medial side. The right kidney sits lower than the left because of the space occupied by the liver just above it. Along with blood vessels, nerves also enter the kidney at the hilum. These mainly sympathetic fibers stimulate the afferent and efferent arterioles, controlling the diameter of the vessels, which, in turn, regulate the rate of urine formation. Also, if blood pressure drops, the nerves stimulate the release of renin, an enzyme that triggers processes for restoring blood pressure. The outer regions of the kidney are packed with over 1 million nephrons: the microscopic functional units of the kidney. These tiny structures consist of two main components: a renal corpuscle—which filters blood plasma—and a renal tubule— where urine is formed. The creation of urine by nephrons involves three processes: glomerular filtration, tubular reabsorption, and tubular secretion. The first step in the creation of urine from blood plasma occurs in the glomerulus as water and small solutes filter out of the blood and into the surrounding space of Bowman’s capsule. Filtration in the glomerulus occurs for the same reason filtration occurs in other blood capillaries: the existence of a pressure gradient. The kidneys employ various mechanisms to control blood flow and ensure a steady glomerular filtration rate. In addition, specialized cells in the distal convoluted tubule monitor the flow rate and composition of filtrate, allowing the renal tubules to make adjustments to alter flow as needed. Finally, a key mechanism for maintaining blood pressure and, therefore, a steady glomerular filtration rate, is the renin-angiotensin-aldosterone system. After the filtrate leaves the glomerulus, it enters the renal tubules. Here, additional chemicals are removed from the filtrate and returned to the blood (tubular reabsorption) while other chemicals are added (tubular secretion). Most of the water, electrolytes, and nutrients are reabsorbed in the proximal convoluted tubules by active and passive transport. Ureters: Connecting the renal pelvis of each kidney with the bladder are slender, muscular tubes called ureters. Each ureter measures about 25 cm (9.8 inches) in length and has a very narrow diameter. Peristaltic waves help propel urine from the renal pelvis toward the bladder. The ureters and urethra serve as passageways for conducting urine away from the kidneys and out of the body while the bladder stores urine until it can be eliminated. Urinary bladder: A collapsible muscular sac, the urinary bladder sits behind the symphysis pubis and
below the peritoneal membrane. In women, it resides in front of the vagina and uterus; in men, it rests on top of the prostate gland. The wall of the bladder, called the detrusor muscle, consists of three layers of smooth muscle. Mucous transitional epithelium lines the bladder. When the bladder is relaxed, this layer of tissue forms folds called rugae. As urine fills the bladder, the rugae flatten and the epithelium thins, allowing the bladder to expand. The floor of the bladder has three openings: two from the ureters (which pass behind the bladder to enter from below) and one from the urethra. Together they form a triangular-shaped, smooth area on the floor of the bladder called the trigone. Infections commonly attack this area of the bladder. At the point where the urethra leaves the bladder, a ring of smooth muscle forms the internal urethral sphincter. This sphincter contracts involuntarily to retain urine in the bladder. A second sphincter, called the external urinary sphincter, exists where the urethra passes through the pelvic floor. This sphincter consists of skeletal muscle and is, therefore, under voluntary control. The urethra is a small tube that conveys urine away from the bladder and out of the body. The opening of the urethra leading to the outside of the body is called the external urinary meatus. Urethra: The structure of the urethra varies between males and females. In women, the urethra is 3 cm (1.2 inches) long and exits the body just in front of the vaginal orifice. In males, the urethra is much longer, measuring about 20 cm (7.9 inches). From the bladder, the urethra passes through the center of the prostate gland, curves around to enter the penis, and then exits the body at the tip of the penis. In men, the urethra performs a dual role. Besides conveying urine, it also conveys semen. Discuss the blood flow through the kidneys The renal artery -which branches off the abdominal aorta- brings blood to the kidney. As it enters the kidney, the renal artery divides, branching into smaller and smaller arteries. The arteries pass through the renal columns and extend into the renal cortex. Blood leaves the glomerulus through an efferent arteriole. The efferent arteriole leads to a network of capillaries around the renal tubules called peritubular capillaries. These capillaries pick up water and solutes reabsorbed by the renal tubules. Blood flows from the peritubular capillaries into larger and larger veins that eventually feed into the renal vein. In the cortex, a series of afferent arterioles arise from the smaller arteries. Each afferent arteriole supplies blood to one nephron. Each afferent arteriole branches into a cluster of capillaries called a glomerulus. The glomerulus is enclosed by Bowman’s capsule. Blood eventually leaves the kidney through the renal vein, which empties into the
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
inferior vena cava. Blood leaves the glomerulus through an efferent arteriole. The efferent arteriole leads to a network of capillaries around the renal tubules called peritubular capillaries. These capillaries pick up water and solutes reabsorbed by the renal tubules. Blood flows from the peritubular capillaries into larger and larger veins that eventually feed into the renal vein. Describe the basic structures and function of the nephron The outer regions of the kidney are packed with over 1 million nephrons: the microscopic functional units of the kidney. These tiny structures consist of two main components: a renal corpuscle—which filters blood plasma—and a renal tubule— where urine is formed. Known as the beginning of the nephron, a renal corpuscle consists of a glomerulus and Bowman’s capsule. Bowman’s capsule—also called a glomerular capsule— consists of two layers of epithelial cells that envelop the glomerulus in an open-ended covering. Fluid filters out of the glomerulus and collects in the space between the two layers of Bowman’s capsule. From there, it flows into the proximal renal tubule on the other side of the capsule. Leading away from the glomerulus are a series of tube-like structures that, collectively, are called the renal tubule. The renal tubule can be divided into four regions: the proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting duct. Arising directly from Bowman’s capsule is the proximal convoluted tubule: a winding, convoluted portion of the renal tubule. Thousands of microvilli that allow absorption to occur line the inside of the proximal convoluted tubule. The renal tubule straightens out and dips into the medulla before turning sharply and returning to the cortex. This entire segment—which consists of a descending limb and an ascending limb—is called the loop of Henle. After returning to the cortex, the ascending limb coils again, forming the distal convoluted tubule. The collecting duct receives drainage from the distal convoluted tubules of several different nephrons. The collecting duct passes into a renal pyramid, where it merges with other collecting ducts to form one tube. That tube opens at a renal papilla into a minor calyx. The renal corpuscle of all nephrons resides in the renal cortex. The loop of Henle dips into the renal medulla; some dip in only slightly whereas others extend deep into the medulla. Blood flows into the glomerulus through the afferent arteriole, which is much larger than the efferent arteriole. Consequently, blood flows in faster than it can leave, which contributes to higher pressure within the glomerular capillaries. The walls of glomerular capillaries are dotted with pores, allowing water and small solutes (such as electrolytes, glucose, amino acids, vitamins, and nitrogenous wastes) to filter out of the blood and into Bowman’s capsule. Blood cells and most plasma proteins, however, are too large to pass through the pores. The fluid that has filtered into Bowman’s capsule flows into the renal tubules. The
amount of fluid filtered by both kidneys—called the glomerular filtration rate (GFR) equals about 180 liters each day, which is 60 times more than the body’s total blood volume. The body reabsorbs about 99% of this filtrate, leaving 1 to 2 liters to be excreted as urine. State how hormones affect the kidneys Aldosterone : When blood levels of Na+ fall, or when the concentration of K+ rises, the adrenal cortex secretes aldosterone. Called the “salt-retaining hormone,” aldosterone prompts the distal convoluted tubule to absorb more Na+ and secrete more K+. Water and Cl- naturally follow Na+, with the end result being that the body retains NaCl and water. Blood volume increases, causing blood pressure (BP) to rise. Reabsorbs NaCl and H2O; Excretes K+ Increased Blood volume Increased BP Atrial natriuretic peptide (ANP) : When blood pressure rises, the atria of the heart secrete ANP, which, in turn, inhibits the secretion of aldosterone and antidiuretic hormone. As a result, the distal convoluted tubule excretes more NaCl and water, thereby reducing blood volume and pressure. Excretes NaCl and H2O Decreased Blood volume Decreased BP Antidiuretic hormone (ADH) : Secreted by the posterior pituitary gland (neurohypophysis), ADH causes the cells of the collecting duct to become more permeable to water. Water flows out of the tubule and into capillaries, causing urine volume to fall and blood volume to increase. Reabsorbs H2O Increased Blood volume Increased BP Parathyroid hormone (PTH) : Secreted by the parathyroid glands in response to low blood calcium levels, PTH prompts the renal tubules to reabsorb more calcium and excrete more phosphate. (If the blood were to retain its phosphate levels, the reabsorbed calcium would be deposited in the bone rather than remain in circulation.) Reabsorbs calcium; Excretes phosphate No effect on blood volume or pressure Describe the neural influences on the storage and elimination of urine from the bladder When the bladder contains 200 ml or more of urine, stretch receptors in the bladder wall send impulses to the sacral region of the spinal cord. The spinal cord then sends motor impulses to the bladder wall to contract and to the internal sphincter to relax. When this happens, voiding will occur involuntarily unless the brain overrides the impulse. The brain has the ability to override the impulse to void because the stretch receptors
in the bladder also send impulses to the micturition center in the pons. The pons integrates information from the stretch receptors with information from other parts of the brain, such as the cerebrum, and evaluates whether the time is appropriate to urinate. If the time to urinate is not appropriate, the brain sends impulses to inhibit urination and to keep the external urinary sphincter contracted. If the time to urinate is appropriate, the brain sends signals to the bladder wall to contract and to the external urethral sphincter to relax, at which point voluntary urination occurs. Discuss the formation and composition of urine Sodium moves by active transport out of the proximal convoluted tubule and into the bloodstream of the peritubular capillaries. Water follows sodium, diffusing rapidly from the tubular fluid into the blood. Glucose, amino acids, chloride, potassium, and bicarbonate follow suit, passing out of the tubules and into the blood. About half of the nitrogenous waste urea is also reabsorbed. Simultaneously, wastes such as ammonia (NH3) and uric acid, as well as drugs (such as aspirin and penicillin), are secreted out of the blood and into the tubules. Tubular secretion of hydrogen ions also occurs, helping to regulate the body’s pH. Water diffuses out of the descending limb of the loop of Henle, further concentrating the filtrate. Sodium and chloride are actively pumped out of the ascending limb of the loop of Henle into interstitial fluid before passing into surrounding capillaries. The thicker wall of the ascending limb prevents water from following the sodium out of the tubule. The distal convoluted tubule and collecting ducts reabsorb variable amounts of water and salts. Specialized cells within this part of the nephron play a role in acid-base balance, reabsorbing potassium and secreting hydrogen into the tubule. Several different hormones help regulate reabsorption by the cells in the distal convoluted tubule. The collecting duct reabsorbs water and concentrates the filtrate, resulting in urine. Urine consists of 95% water and 5% dissolved substances. The dissolved substances include nitrogenous wastes—such as urea, uric acid, ammonia, and creatinine—as well as other solutes, such as sodium, potassium, and sulfates. The components of urine reveal a great deal about the health of the kidneys as well as other organs of the body. That’s why a urinalysis (an examination of the characteristics of urine) is one of the most commonly prescribed medical tests.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Focus tips: P. 436 Know this diagram and be able to locate the duodenum, jejunum, ileum, all the parts of the colon, cecum, rectum, stomach. P. 400 be able to locate and spell: kidneys, bladder, urethra and ureters. Bile salts digestive function- digests and absorbs fats p. 434 The most important component of bile is bile salts. Formed in the liver from cholesterol, bile salts aid in the digestion and absorption of fat in the small intestine. After secretion, 80% of bile salts are reabsorbed in the final section of the small intestine (the ileum). It is then returned to the liver, where hepatocytes absorb and then secrete the bile once again. Name the accessory organs of the digestive system, digestion begins where? The accessory organs include the: Teeth : Digestion begins when food enters the mouth and is chewed : a process called mastication. Besides breaking food into pieces small enough to be swallowed, chewing allows food to become moistened with saliva. The adult mouth contains 32 permanent teeth designed to cut, tear, and grind food. Tongue : The tongue is a skeletal muscle covered by a mucous membrane. It repositions food in the mouth during chewing; it also contains taste buds within projections called lingual papillae. Salivary glands : Salivary glands secrete saliva, a clear fluid consisting mostly of water, but also containing mucus, an enzyme that kills bacteria, antibacterial compounds, electrolytes, and two digestive enzymes. The mouth also contains minor salivary glands in the tongue, inside the lips, and on the inside of the cheeks. The parotid gland lies just underneath the skin anterior to the ear. Its duct drains saliva to an area near the second upper molar. The mumps virus causes swelling and inflammation of the parotid gland. The submandibular gland empties into the mouth on either side of the lingual frenulum. The sublingual gland drains through multiple ducts onto the floor of the mouth. Enzymes contained in saliva begin the digestion process: amylase breaks down starch while lipase begins the digestion of fat. Liver : The body’s largest gland, the liver fills the upper right abdomen below the diaphragm. Even more impressive than its size is its function: the liver performs more than 250 tasks, including storing and releasing glucose, processing vitamins and minerals, filtering toxins, and recycling old blood cells. Nutrient-rich blood from the stomach and intestine enters the lobule through small branches of the portal vein. Oxygen-rich blood enters the lobule through small branches of the hepatic artery. The blood filters through the sinusoids, allowing the cells to remove nutrients (such as glucose, amino acids, iron, and vitamins) as well as hormones, toxins, and drugs. At the same time, the liver secretes substances—such as clotting factors, albumin, angiotensinogen, and glucose—into the blood for distribution throughout the body. Also, phagocytic cells called Kupffer cells remove bacteria, worn-out red blood cells, and
debris from the bloodstream. 5The central vein carries the processed blood out of the liver. Canaliculi carry bile secreted by hepatic cells and ultimately drain into the right and left hepatic ducts. Each day, the liver secretes up to 1 liter of bile: a yellow-green fluid containing minerals, phospholipids, bile salts, bile pigments, and cholesterol. The main bile pigment is bilirubin, which results from the breakdown of hemoglobin. However, the most important component of bile is bile salts. Formed in the liver from cholesterol, bile salts aid in the digestion and absorption of fat in the small intestine. After secretion, 80% of bile salts are reabsorbed in the final section of the small intestine (the ileum). It is then returned to the liver, where hepatocytes absorb and then secrete the bile once again. The 20% of bile not reabsorbed is excreted in feces. Pancreas : The pancreas lies behind the stomach; its head is nestled in the curve of the duodenum and its tapered tail sits below the spleen and above the left kidney. The pancreas is both an endocrine and exocrine gland. Its endocrine function centers on pancreatic islets that secrete insulin and glucagon. Most of the pancreas, though, consists of exocrine tissue. Each day, the pancreas secretes about 1.5 liters of pancreatic juice—essentially digestive enzymes and an alkaline fluid—into the small intestine. Acinar cells secrete digestive enzymes in an inactive form; once activated in the duodenum, the enzymes help break down lipids, proteins, and carbohydrates. Epithelial cells in pancreatic ducts secrete sodium bicarbonate, which buffers the highly acidic chyme entering the duodenum from the stomach. Gallbladder : A sac attached to the underside of the liver, the gallbladder stores and concentrates bile. The gallbladder is about 3 to 4 inches (7–10 cm) long and holds 30 to 50 ml of bile. The bile duct merges with the duct of the pancreas to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla enters the duodenum at a raised area called the major duodenal papilla. A sphincter called the hepatopancreatic sphincter (sphincter of Oddi) controls the flow of bile and pancreatic juice into the duodenum. Location, function of mesentery p. 425 Layers of visceral peritoneum called mesenteries suspend the digestive organs within the abdominal cavity while anchoring them loosely to the abdominal wall. Mesenteries also contain blood vessels, nerves, lymphatic vessels, and lymph nodes that supply the digestive tract. Main component of saliva Salivary glands secrete saliva, a clear fluid consisting mostly of water , but also containing mucus, an enzyme that kills bacteria, antibacterial compounds, electrolytes, and two digestive enzymes. Location/function of ileocecal valve; prevents backflow of intestinal contents, keeps material moving forward . p440
At the point where the ileum meets the large intestine is the ileocecal valve, which helps ensure that material moves in a forward direction only. Location, function, purpose of rugae When the stomach is empty, the mucosa and submucosa are wrinkled into folds called rugae. As the stomach fills with food, the rugae flatten and the stomach expands. Mucous transitional epithelium lines the bladder. When the bladder is relaxed, this layer of tissue forms folds called rugae. As urine fills the bladder, the rugae flatten and the epithelium thins, allowing the bladder to expand. Intestine where most water is absorbed Large intestine : Once the food has been processed and its nutrients absorbed, the remaining residue is ready to leave the small intestine for the large intestine. In fact, about 500 ml of residue—consisting of undigested food, sloughed off epithelial cells, minerals, salts, and bacteria—enter the large intestine each day. The large intestine absorbs large amounts of water from the residue before passing the resulting waste material (feces) out of the body. Location, function of lower esophageal sphincter A muscular sphincter called the lower esophageal sphincter (LES) helps prevent the backflow of stomach acid into the esophagus. Location, function of esophagus Connecting the pharynx to the stomach is the esophagus: a muscular tube about 10 inches (25 cm) long. Lying posterior to the trachea, the esophagus travels through the mediastinum, penetrates the diaphragm, and enters the stomach. Glands within the wall of the esophagus secrete mucus that helps lubricate the food bolus as it passes through. When a bolus enters the esophagus, it triggers wave-like muscular contractions (peristalsis) that propel the food toward the stomach. Substance carried in common bile duct p. 434 Bile reaches the gallbladder through a series of ducts. It leaves the liver by the right and left hepatic ducts. These two ducts converge to form the common hepatic duct, which goes on to become the common bile duct. Bile from the liver first fills the common bile duct before backing up into the gallbladder through the cystic duct. Defecation-body at work box p441 filling of feces into the rectum stim defecation reflex Intestinal contractions move feces through the colon and toward the rectum. Haustral contractions: As a haustrum fills with residue, it becomes distended, which stimulates the haustrum to contract. Besides mixing the residue, the contraction pushes
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
the residue into the next haustrum. Haustral contractions generally occur every 30 minutes. Stronger peristaltic contractions called mass movements, move larger amounts of material several inches at a time along the colon. In particular, these movements are triggered by the filling of the stomach or duodenum. The mass movement of feces into the rectum stimulates the defecation reflex: the rectum contracts and the internal anal sphincter relaxes. When the external anal sphincter relaxes (which is under voluntary control to prevent the uncontrolled release of feces), feces is expelled from the body (defecation). Digestive enzymes Lipase, Trypsin, Amylase- what substance do they digest Salivary glands: Amylase - Starch Lipase - Fat Stomach: Pepsin - Protein Pancreas: Proteases (trypsin, chymotrypsin) - Protein Lipase - Fats Amylase - Starch Intestine: Peptidases - Peptides Sucrase – Sucrose (Cane Sugar) Lactase – Lactose (Milk Sugar) Maltase – Maltose (Malt Sugar) Location, function of gallbladder Gallbladder : A sac attached to the underside of the liver, the gallbladder stores and concentrates bile. The gallbladder is about 3 to 4 inches (7–10 cm) long and holds 30 to 50 ml of bile. The bile duct merges with the duct of the pancreas to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla enters the duodenum at a raised area called the major duodenal papilla. A sphincter called the hepatopancreatic sphincter (sphincter of Oddi) controls the flow of bile and pancreatic juice into the duodenum. Jejunum has millions of microscopic projections for what purpose p. 436 pink box Many large, closely spaced folds and millions of microscopic projections give the jejunum an enormous surface area, making it an ideal location for nutrient absorption.
Location/function of acinar cells, liver sinusoids, hepatocytes The blood filters through the sinusoids, allowing the cells to remove nutrients (such as glucose, amino acids, iron, and vitamins) as well as hormones, toxins, and drugs. At the same time, the liver secretes substances—such as clotting factors, albumin, angiotensinogen, and glucose—into the blood for distribution throughout the body. Acinar cells secrete digestive enzymes in an inactive form; once activated in the duodenum, the enzymes help break down lipids, proteins, and carbohydrates. PANCREAS A central vein passes through the core of each lobule. Sheets of hepatic cells (called hepatocytes) fan out from the center of the lobule. In between the sheets of cells are passageways filled with blood called sinusoids. Tiny canals called canaliculi carry bile secreted by hepatocytes. LIVER Substances found in urine- substance that should NOT be in urine Urine consists of 95% water and 5% dissolved substances. The dissolved substances include nitrogenous wastes—such as urea, uric acid, ammonia, and creatinine—as well as other solutes, such as sodium, potassium, and sulfates. Glucose, blood, free hemoglobin, albumin, ketones, and bile pigments are not normally found in urine; their presence indicates a disease process. Darker urine usually results from poor hydration. Cloudy urine may result from bacteria, indicating an infection. A pungent smell (such as in a stale diaper) results when urine is allowed to stand: bacteria multiplies and converts urea into ammonia. A sweet, fruity odor (acetone) often occurs in diabetes. A rotten odor may indicate a urinary tract infection. A high specific gravity could result from dehydration (reflecting a low volume of water in relation to the amount of solids). A high pH reflects alkalosis. A low pH indicates acidosis. Function of vit C; how is it absorbed Synthesis of collagen, antioxidant, red blood cell formation, wound healing, aids in iron absorption. Water-soluble. Functions of Insulin, cholecystokinin, ghrelin, peptide YY, bile salts Insulin levels increase rapidly after eating to counteract the rise in glucose levels. The amount of insulin released varies according to the amount of body fat. Like leptin, insulin alerts the brain as to the amount of body fat and, therefore, suppresses appetite.
Cholecystokinin (CCK) is secreted by cells in the duodenum and jejunum; in addition to stimulating the secretion of bile and pancreatic enzymes, this hormone also suppresses appetite. Secreted by parietal cells in the stomach, especially when the stomach is empty, ghrelin produces the sensation of hunger. Ghrelin secretions decrease for about 3 hours after a meal. Peptide YY (PYY)—which is secreted by enteroendocrine cells in the ileum and colon— signals satiety and, therefore, serves as a prompt to stop eating. The most important component of bile is bile salts. Formed in the liver from cholesterol, bile salts aid in the digestion and absorption of fat in the small intestine. After secretion, 80% of bile salts are reabsorbed in the final section of the small intestine (the ileum). It is then returned to the liver, where hepatocytes absorb and then secrete the bile once again. Body's primary energy source Carbohydrates are the body’s primary energy source. Function of aldosterone, ADH Aldosterone : When blood levels of Na+ fall, or when the concentration of K+ rises, the adrenal cortex secretes aldosterone. Called the “salt-retaining hormone,” aldosterone prompts the distal convoluted tubule to absorb more Na+ and secrete more K+. Water and Cl- naturally follow Na+, with the end result being that the body retains NaCl and water. Blood volume increases, causing blood pressure (BP) to rise. Reabsorbs NaCl and H2O; Excretes K+ Increased Blood volume Increased BP Antidiuretic hormone (ADH) : Secreted by the posterior pituitary gland (neurohypophysis), ADH causes the cells of the collecting duct to become more permeable to water. Water flows out of the tubule and into capillaries, causing urine volume to fall and blood volume to increase. Reabsorbs H2O Increased Blood volume Increased BP What is catabolism, anabolism, basal metabolic rate, calorie The amount of energy the body needs at rest (such as that required for the heart to beat, the lungs to breathe, and the kidneys to function) is called the basal metabolic rate (BMR). The BMR for adults is about 2000 calories/day for males and slightly less for females.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Energy expenditure is measured by the output of heat from the body. In nutrition, the unit of heat often used is the calorie: the amount of heat (or energy) needed to raise the temperature of 1 gram of water by 1 degree Celsius. In other words, calories are energy that the body uses as fuel. Age gender body size affect metabolic rate Metabolism involves two processes: Catabolism: Used in the metabolism of carbohydrates and lipids, this process breaks down complex substances into simpler ones or into energy. Anabolism: Used in protein metabolism, this process forms complex substances out of simpler ones. Regulation of temperature-radiation/conduction/convection/evaporation. To balance the production of heat, the body loses heat by three means: radiation, conduction, and evaporation. Radiation involves the transfer of heat through the air by electromagnetic heat waves. Conduction involves the transfer of heat between two materials that touch each other. In other words, heat passes out of our bodies and into objects that we touch, such as our clothes. Evaporation requires heat to change water into a gas. That’s why perspiration can effectively cool the body. Sweat causes the skin to become wet; then, as evaporation occurs, heat is drawn from the body. Part of brain that regulates body temp- hypothalamus . Specific gravity in urine. what is it, what does it measure Specific gravity (Indicates the amount of solid matter in a liquid). A high specific gravity could result from dehydration. Function of plasma protein Albumin Colloid osmotic pressure: Process whereby albumin in the blood pulls tissue fluid into capillaries Nephron, location function The outer regions of the kidney are packed with over 1 million nephrons: the microscopic functional units of the kidney. These tiny structures consist of two main components: a renal corpuscle—which filters blood plasma—and a renal tubule— where urine is formed. Known as the beginning of the nephron, a renal corpuscle consists of a glomerulus and Bowman’s capsule. Bowman’s capsule—also called a glomerular capsule—consists of two layers of epithelial cells that envelop the glomerulus in an open-ended covering. Fluid filters out of the glomerulus and collects in the space between the two layers of
Bowman’s capsule. From there, it flows into the proximal renal tubule on the other side of the capsule. Leading away from the glomerulus are a series of tube-like structures that, collectively, are called the renal tubule. The renal tubule can be divided into four regions: the proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting duct. Arising directly from Bowman’s capsule is the proximal convoluted tubule: a winding, convoluted portion of the renal tubule. Thousands of microvilli that allow absorption to occur line the inside of the proximal convoluted tubule. The renal tubule straightens out and dips into the medulla before turning sharply and returning to the cortex. This entire segment—which consists of a descending limb and an ascending limb—is called the loop of Henle. After returning to the cortex, the ascending limb coils again, forming the distal convoluted tubule. The collecting duct receives drainage from the distal convoluted tubules of several different nephrons. The collecting duct passes into a renal pyramid, where it merges with other collecting ducts to form one tube. That tube opens at a renal papilla into a minor calyx. The renal corpuscle of all nephrons resides in the renal cortex. The loop of Henle dips into the renal medulla; some dip in only slightly whereas others extend deep into the medulla. Blood flows into the glomerulus through the afferent arteriole, which is much larger than the efferent arteriole. Consequently, blood flows in faster than it can leave, which contributes to higher pressure within the glomerular capillaries. The walls of glomerular capillaries are dotted with pores, allowing water and small solutes (such as electrolytes, glucose, amino acids, vitamins, and nitrogenous wastes) to filter out of the blood and into Bowman’s capsule. Blood cells and most plasma proteins, however, are too large to pass through the pores. The fluid that has filtered into Bowman’s capsule flows into the renal tubules. The amount of fluid filtered by both kidneys—called the glomerular filtration rate (GFR) equals about 180 liters each day, which is 60 times more than the body’s total blood volume. The body reabsorbs about 99% of this filtrate, leaving 1 to 2 liters to be excreted as urine. Location function of glomerulus The first step in the creation of urine from blood plasma occurs in the glomerulus as water and small solutes filter out of the blood and into the surrounding space of Bowman’s capsule. Filtration in the glomerulus occurs for the same reason filtration occurs in other blood capillaries: the existence of a pressure gradient. Bowman’s capsule—also called a glomerular capsule—consists of two layers of epithelial cells that envelop the glomerulus in an open-ended covering.
Fluid filters out of the glomerulus and collects in the space between the two layers of Bowman’s capsule. From there, it flows into the proximal renal tubule on the other side of the capsule. Location, function of kidney Kidneys: The kidneys lie against the posterior abdominal wall and underneath the 12th rib. They are also retroperitoneal, meaning that they are posterior to the parietal peritoneum. The ribs offer some protection to the kidneys, as does a heavy cushion of fat encasing each organ. Each kidney measures about 4 inches (10 cm) long, 2 inches (5 cm) wide, and 1 inch (2.5 cm) thick; they extend from the level of the T12 vertebra to the L3 vertebra. Structures (such as blood vessels, the ureters, and nerves) enter and leave the kidney through a slit called the hilum—located in a concave notch on the medial side. The right kidney sits lower than the left because of the space occupied by the liver just above it. Along with blood vessels, nerves also enter the kidney at the hilum. These mainly sympathetic fibers stimulate the afferent and efferent arterioles, controlling the diameter of the vessels, which, in turn, regulate the rate of urine formation. Also, if blood pressure drops, the nerves stimulate the release of renin, an enzyme that triggers processes for restoring blood pressure. The outer regions of the kidney are packed with over 1 million nephrons: the microscopic functional units of the kidney. These tiny structures consist of two main components: a renal corpuscle—which filters blood plasma—and a renal tubule— where urine is formed. The creation of urine by nephrons involves three processes: glomerular filtration, tubular reabsorption, and tubular secretion. The first step in the creation of urine from blood plasma occurs in the glomerulus as water and small solutes filter out of the blood and into the surrounding space of Bowman’s capsule. Filtration in the glomerulus occurs for the same reason filtration occurs in other blood capillaries: the existence of a pressure gradient. The kidneys employ various mechanisms to control blood flow and ensure a steady glomerular filtration rate. In addition, specialized cells in the distal convoluted tubule monitor the flow rate and composition of filtrate, allowing the renal tubules to make adjustments to alter flow as needed. Finally, a key mechanism for maintaining blood pressure and, therefore, a steady glomerular filtration rate, is the renin-angiotensin-aldosterone system. After the filtrate leaves the glomerulus, it enters the renal tubules. Here, additional chemicals are removed from the filtrate and returned to the blood (tubular reabsorption) while other chemicals are added (tubular secretion). Most of the water, electrolytes, and nutrients are reabsorbed in the proximal convoluted tubules by active and passive transport. How do kidneys respond to elevated acidity in the body- excrete hydrogen ions Voluntary/involuntary control of urination
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
When the bladder contains 200 ml or more of urine, stretch receptors in the bladder wall send impulses to the sacral region of the spinal cord. The spinal cord then sends motor impulses to the bladder wall to contract and to the internal sphincter to relax. When this happens, voiding will occur involuntarily unless the brain overrides the impulse. The brain has the ability to override the impulse to void because the stretch receptors in the bladder also send impulses to the micturition center in the pons. The pons integrates information from the stretch receptors with information from other parts of the brain, such as the cerebrum, and evaluates whether the time is appropriate to urinate. If the time to urinate is not appropriate, the brain sends impulses to inhibit urination and to keep the external urinary sphincter contracted. If the time to urinate is appropriate, the brain sends signals to the bladder wall to contract and to the external urethral sphincter to relax, at which point voluntary urination occurs. location/function of glomerulus, bowman's capsule, nephron The outer regions of the kidney are packed with over 1 million nephrons: the microscopic functional units of the kidney. These tiny structures consist of two main components: a renal corpuscle—which filters blood plasma—and a renal tubule— where urine is formed. Known as the beginning of the nephron, a renal corpuscle consists of a glomerulus and Bowman’s capsule. Bowman’s capsule—also called a glomerular capsule—consists of two layers of epithelial cells that envelop the glomerulus in an open-ended covering. Fluid filters out of the glomerulus and collects in the space between the two layers of Bowman’s capsule. From there, it flows into the proximal renal tubule on the other side of the capsule. Leading away from the glomerulus are a series of tube-like structures that, collectively, are called the renal tubule. The renal tubule can be divided into four regions: the proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting duct. Arising directly from Bowman’s capsule is the proximal convoluted tubule: a winding, convoluted portion of the renal tubule. Thousands of microvilli that allow absorption to occur line the inside of the proximal convoluted tubule. The renal tubule straightens out and dips into the medulla before turning sharply and returning to the cortex. This entire segment—which consists of a descending limb and an ascending limb—is called the loop of Henle. After returning to the cortex, the ascending limb coils again, forming the distal convoluted tubule. The collecting duct receives drainage from the distal convoluted tubules of several different nephrons. The collecting duct passes into a renal pyramid, where it merges with other collecting ducts to form one tube. That tube opens at a renal papilla into a minor calyx.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
The renal corpuscle of all nephrons resides in the renal cortex. The loop of Henle dips into the renal medulla; some dip in only slightly whereas others extend deep into the medulla. Blood flows into the glomerulus through the afferent arteriole, which is much larger than the efferent arteriole. Consequently, blood flows in faster than it can leave, which contributes to higher pressure within the glomerular capillaries. The walls of glomerular capillaries are dotted with pores, allowing water and small solutes (such as electrolytes, glucose, amino acids, vitamins, and nitrogenous wastes) to filter out of the blood and into Bowman’s capsule. Blood cells and most plasma proteins, however, are too large to pass through the pores. The fluid that has filtered into Bowman’s capsule flows into the renal tubules. The amount of fluid filtered by both kidneys—called the glomerular filtration rate (GFR) equals about 180 liters each day, which is 60 times more than the body’s total blood volume. The body reabsorbs about 99% of this filtrate, leaving 1 to 2 liters to be excreted as urine. GFR p. 395 box #3 also read last sentence in green box. The fluid that has filtered into Bowman’s capsule flows into the renal tubules. The amount of fluid filtered by both kidneys—called the glomerular filtration rate (GFR)— equals about 180 liters each day, which is 60 times more than the body’s total blood volume. The body reabsorbs about 99% of this filtrate, leaving 1 to 2 liters to be excreted as urine. Most of the calcium, iron, and thyroid hormone in the blood is bound to plasma proteins, which prevents these solutes from being filtered out of the blood in the glomerulus. Process of chemical digestion, digestive accessory organs Liver: The body’s largest gland, the liver fills the upper right abdomen below the diaphragm. Even more impressive than its size is its function: the liver performs more than 250 tasks, including storing and releasing glucose, processing vitamins and minerals, filtering toxins, and recycling old blood cells. Nutrient-rich blood from the stomach and intestine enters the lobule through small branches of the portal vein. Oxygen-rich blood enters the lobule through small branches of the hepatic artery. The blood filters through the sinusoids, allowing the cells to remove nutrients (such as glucose, amino acids, iron, and vitamins) as well as hormones, toxins, and drugs. At the same time, the liver secretes substances—such as clotting factors, albumin, angiotensinogen, and glucose—into the blood for distribution throughout the body. Also, phagocytic cells called Kupffer cells remove bacteria, worn-out red blood cells, and debris from the bloodstream. 5The central vein carries the processed blood out of the liver. Canaliculi carry bile secreted by hepatic cells and ultimately drain into the right and left hepatic ducts. Each day, the liver secretes up to 1 liter of bile: a yellow-green fluid
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
containing minerals, phospholipids, bile salts, bile pigments, and cholesterol. The main bile pigment is bilirubin, which results from the breakdown of hemoglobin. However, the most important component of bile is bile salts. Formed in the liver from cholesterol, bile salts aid in the digestion and absorption of fat in the small intestine. After secretion, 80% of bile salts are reabsorbed in the final section of the small intestine (the ileum). It is then returned to the liver, where hepatocytes absorb and then secrete the bile once again. The 20% of bile not reabsorbed is excreted in feces. Pancreas: The pancreas lies behind the stomach; its head is nestled in the curve of the duodenum and its tapered tail sits below the spleen and above the left kidney. The pancreas is both an endocrine and exocrine gland. Its endocrine function centers on pancreatic islets that secrete insulin and glucagon. Most of the pancreas, though, consists of exocrine tissue. Each day, the pancreas secretes about 1.5 liters of pancreatic juice—essentially digestive enzymes and an alkaline fluid—into the small intestine. Acinar cells secrete digestive enzymes in an inactive form; once activated in the duodenum, the enzymes help break down lipids, proteins, and carbohydrates. Epithelial cells in pancreatic ducts secrete sodium bicarbonate, which buffers the highly acidic chyme entering the duodenum from the stomach. Gallbladder: A sac attached to the underside of the liver, the gallbladder stores and concentrates bile. The gallbladder is about 3 to 4 inches (7–10 cm) long and holds 30 to 50 ml of bile. The bile duct merges with the duct of the pancreas to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla enters the duodenum at a raised area called the major duodenal papilla. A sphincter called the hepatopancreatic sphincter (sphincter of Oddi) controls the flow of bile and pancreatic juice into the duodenum. Chemical digestion: The second phase of digestion uses digestive enzymes produced in the salivary glands, stomach, pancreas, and small intestines to break down food particles into nutrients (such as glucose, amino acids, and fatty acids) that cells can use. Location, function of large intestine, parietal cells, jejunum, stomach primary function, gallbladder, mesentery Parietal cells secrete hydrochloric acid and intrinsic factor (which is necessary for the absorption of vitamin B12). Hydrochloric acid helps kill microbes in swallowed food. The stomach, a muscular sac whose primary function is to store food. Layers of visceral peritoneum called mesenteries suspend the digestive organs within the abdominal cavity while anchoring them loosely to the abdominal wall. Mesenteries also contain blood vessels, nerves, lymphatic vessels, and lymph nodes that supply the digestive tract. The jejunum constitutes the next 8 feet (2.4 m) of small intestine. Many large, closely spaced folds and millions of microscopic projections give the jejunum an enormous surface area, making it an ideal location for nutrient absorption. The wall of the jejunum
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
is thick and muscular with a rich blood supply, which imparts a red color to this part of the intestine. Once the food has been processed and its nutrients absorbed, the remaining residue is ready to leave the small intestine for the large intestine. In fact, about 500 ml of residue —consisting of undigested food, sloughed off epithelial cells, minerals, salts, and bacteria—enter the large intestine each day. The large intestine absorbs large amounts of water from the residue before passing the resulting waste material (feces) out of the body. Gallbladder: A sac attached to the underside of the liver, the gallbladder stores and concentrates bile. The gallbladder is about 3 to 4 inches (7–10 cm) long and holds 30 to 50 ml of bile. The bile duct merges with the duct of the pancreas to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla enters the duodenum at a raised area called the major duodenal papilla. A sphincter called the hepatopancreatic sphincter (sphincter of Oddi) controls the flow of bile and pancreatic juice into the duodenum. p. 457 Body at work- neg nitrogen balance/pos nitrogen balance The body doesn’t store amino acids or proteins like it does fat or carbohydrates; therefore, protein turnover must occur continually. Remarkably, in healthy adults, the amount of protein being broken down equals the amount of protein being created. This state—in which the rate of protein anabolism equals the rate of protein catabolism—is called protein balance. Recall that the catabolism of protein yields nitrogenous waste products. Therefore, if the body is in protein balance, it’s also in nitrogen balance: The amount of nitrogen being consumed in the form of protein-containing foods equals the amount of nitrogen being excreted in urine, feces, and sweat as a waste product. When more proteins are being catabolized than are being created—such as during starvation or a wasting illness—the amount of nitrogen in the urine exceeds the amount of nitrogen in the protein foods ingested. In this instance, the body is said to be in a state of negative nitrogen balance. On the other hand, if the amount of nitrogen being consumed through foods is greater than the nitrogen output in urine, the body is in a state of positive nitrogen balance. This situation—in which protein anabolism outpaces protein catabolism—occurs when large amounts of tissue are being synthesized, such as during periods of growth, during pregnancy, or when recovering from a wasting illness. p. 458 heat production and loss. Most of body's heat comes from Most of the body’s heat results as a byproduct of the chemical reactions occurring in cells. The cells of the muscles, brain, liver, and endocrine glands provide the greatest portion of heat when the body is at rest.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Vit c dietary source, function, deficiency beneficial for wound healing p. 452. Citrus fruits, green vegetables Synthesis of collagen, antioxidant, red blood cell formation, wound healing, aids in iron absorption Scurvy; degeneration of skin, bone, and blood vessels Function of renin, when, where is it produced, renin-angiotensin mechanism A drop in BP leads to decreased blood flow to the kidneys. Specialized cells found primarily in the afferent arterioles—called juxtaglomerular cells —respond by releasing the enzyme renin. Renin converts the inactive plasma protein angiotensinogen (made in the liver) into angiotensin I. Angiotensin I circulates to the lungs, where angiotensin-converting enzyme (ACE) converts it into angiotensin II. Angiotensin II stimulates the adrenal glands to secrete aldosterone. Aldosterone causes the distal convoluted tubule to retain sodium, which leads to increased retention of water. Blood volume increases and blood pressure rises. The liver does or does not produce digestive enzymes Yes, bile salts in bile Location/function: stomach rugae, pyloric sphincter /lower esophageal sphincter, ileocecal valve Pyloric: stomach to duodenum Lower Esophageal: esophagus to stomach Ileocecal: Ileus to Cecum Rugae: wrinkled folds that expand surface area Wasting illness, negative nitrogen balance When more proteins are being catabolized than are being created—such as during starvation or a wasting illness—the amount of nitrogen in the urine exceeds the amount of nitrogen in the protein foods ingested. In this instance, the body is said to be in a state of negative nitrogen balance. Key Terms Acinar cells : Pancreatic cells that secrete digestive enzymes in an inactive form Amylase : Enzyme contained in saliva that breaks down starch Anal canal : Last inch of the rectum; opens to the exterior through the anus Appendix : Tubular organ attached to the lower end of the cecum; serves as a source for immune cells
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Ascending colon : First main part of large intestine, which extends upward toward the liver Ascites : Accumulation of fluid in the peritoneal cavity Bile : Yellow-green fluid secreted by the liver that aids in digestion Cecum : Blind pouch that serves as the beginning of the large intestine Cementum : Connective tissue covering dentin in the root of a tooth Cephalic phase : Phase of digestion that begins with the sight, smell, taste, or thought of food Chief cells : Cells in the gastric mucosa that secrete digestive enzymes Chyme : Semifluid mixture consisting of particles of food mixed with digestive juices Dentin : Firm, yellowish tissue forming the bulk of a tooth Descending colon : Portion of large intestine extending downward along the left side of the abdominal cavity Duodenum : The first 10 inches of small intestine; the portion of intestine that performs most digestive processes Enteric nervous system : Network of nerves innervating the digestive system Enteroendocrine cells : Cells in the gastric mucosa that secrete the hormone ghrelin Esophagus : Muscular tube connecting the pharynx to the stomach Gallbladder : Sac attached to the liver that stores and concentrates bile Gastric phase : Phase of digestion that begins when food enters the stomach Gastric pits : Depressions within the gastric mucosa containing glands that secrete components of gastric juice Gingiva : Tissue surrounding the necks of teeth; the gums Greater omentum : Large apron-like portion of mesentery that hangs over the small intestine Hard palate : Bony structure that separates the mouth from the nasal cavity Haustra : Pouches along the length of the large intestine Hepatic artery : Delivers oxygenated blood to the liver Ileocecal valve : Valve at the point where the ileum meets the large intestine; helps ensure that material moves only in a forward direction Ileum : The third and last portion of the small intestine Intestinal crypt : Pores at the vases of gastric villi that contain goblet cells Intestinal phase : Phase of digestion that begins when chyme moves into the duodenum Intraperitoneal : Organs enclosed by mesentery on both sides, placing them within the peritoneal cavity Jejunum : The second portion of the small intestine; location where many nutrients are absorbed Lacteal : Lymph vessel found inside the villi of the small intestine Lesser omentum : Portion of mesentery extending from lesser curve of stomach to the liver
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Lingual frenulum : Fold of mucous membrane that anchors the tongue to the floor of the mouth Lipase : Enzyme that digests fat Mastication : Process of chewing, which begins the digestion of food Mesentery : Sheet of connective tissue that suspends the digestive organs within the abdominal cavity Mucous cells : Gastric cells that secrete mucus Parietal cells : Gastric cells that secrete hydrochloric acid and intrinsic factor Parotid gland : Salivary gland located just underneath the skin anterior to the ear Pepsin : Enzyme secreted in the stomach that hydrolyzes peptide bonds Peristalsis : Wave-like muscular contractions that propel food along the digestive tract Portal vein : Carries oxygen-poor but nutrient-rich blood from the digestive organs and spleen to the liver Proteases : Enzymes working in the stomach and small intestine to break peptide bonds Rectum : Last 7 to 8 inches of the intestine Retroperitoneal : Organs outside the peritoneal cavity; these organs lie against the dorsal abdominal wall and are covered by mesentery only on ventral sides Rugae : Folds of mucosa and submucosa in the stomach Salivary glands : Glands in the oral cavity that secrete saliva Segmentation : Type of contraction in the small intestine that involves ring-like constrictions Sigmoid colon : Lower portion of the colon that forms an S shape down to the rectum Soft palate : Structure consisting mostly of skeletal muscle that forms an arch between the mouth and nasopharynx Sublingual gland : Salivary gland that drains through multiple ducts onto the floor of the mouth Submandibular gland : Salivary gland that empties into the mouth on either side of the lingual frenulum Transverse colon : Middle part of the large intestine, passing below the liver, stomach, and spleen Uvula : Cone-shaped process hanging downward from the soft palate Aerobic : Processes that require oxygen Anabolism : Process used in protein metabolism that forms complex substances out of simpler ones Anaerobic : Processes occurring without oxygen Basal metabolic rate : The amount of energy the body needs at rest Calorie : The amount of heat needed to raise the temperature of 1 gram of water by 1° Celsius Carbohydrates : The body’s primary energy source Catabolism : Process used in the metabolism of carbohydrates and lipids that breaks down complex substances into simpler ones or into energy
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Complete protein : Foods that supply all the essential amino acids Conduction : Process by which heat is transferred between two materials touching each other Core temperature : Temperature of the body’s deeper regions Dietary fiber : Carbohydrate that resists digestion in the small intestine Disaccharides : Broken down into monosaccharides during digestive process; also called simple sugars Essential amino acids : Amino acids that must be obtained through diet Essential fatty acid : Fat that must be obtained through the diet Essential nutrients : Nutrients essential in the diet because they cannot be synthesized by the body Evaporation : Process by which heat changes water into a gas as a means of regulating temperature Fat-soluble vitamins : Vitamins absorbed with dietary fat, after which they are stored in the liver and fat tissues of the body; mega-dosing may lead to toxicity Ghrelin : Hormone secreted by cells in the stomach that stimulates appetite. Gluconeogenesis : Process by which the body creates glucose from noncarbohydrates, such as fats and amino acids Glycogenesis : Process by which the liver converts glucose into glycogen it then stores Glycogenolysis : Process by which glycogen stored in the liver is broken down into glucose Glycolysis : The breakdown of carbohydrates for energy Incomplete proteins : Foods that lack one or more essential amino acids Ketoacidosis : Complication of diabetes occurring when the body produces high levels of ketone bodies as a result of fat catabolism Lipids : Fats that act as a reservoir of excess energy Macronutrients : Substances (such as fat, protein, and carbohydrates) required in large amounts in the human diet Metabolism : Chemical processes occurring in cells that transform nutrients into energy or into materials the body can use or store Micronutrients : Substances (such as vitamins and minerals) needed only in small quantities Mineral : An inorganic element or compound needed for numerous vital functions Monosaccharides : Carbohydrate known as simple sugars; absorbed through small intestine without being broken down Negative nitrogen balance : When more proteins are being catabolized than are being created, such as during starvation or a wasting illness Nonessential amino acids : Amino acids the body can synthesize, making them nonessential in the diet Nonessential nutrients : Nutrients not essential in the diet because the body can synthesize them
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Nutrients : Usable food components that supply the body with chemicals necessary for energy Polysaccharides : Carbohydrates known as complex carbohydrates Positive nitrogen balance : When the amount of nitrogen being consumed through foods is greater than the nitrogen output in urine; occurs when large amounts of tissue are being synthesized, such as during periods of growth Radiation : Process by which heat is transferred through the air by electromagnetic heat waves Shell temperature : Temperature near the body’s surface Short-chain fatty acids : Fatty acids produced from fermentation of dietary fiber by bacteria in the gut Thermoregulation : Process that allows the body to maintain its core internal temperature Trans fat : Created in an industrial process that adds hydrogen to liquid vegetable shortening to make it more solid; primarily found in processed foods Vitamins : Vital nutrients, obtained mostly through food and needed for metabolism Water-soluble vitamins : Vitamins absorbed with water in the small intestine; are not stored in the body and thus pose little risk for toxicity Aldosterone : Hormone that causes the distal convoluted tubule to retain sodium, which leads to the retention of water, resulting in increased blood pressure Angiotensin : A plasma protein produced when renin is released from the kidney; angiotensin II stimulates the adrenal glands to secrete aldosterone Antidiuretic hormone : Hormone that inhibits diuresis by stimulating the kidneys to conserve water Bowman’s capsule : Two layers of epithelial cells that envelop the glomerulus in an open-ended covering; also called a glomerular capsule Calyx : A cup-like structure that collects urine leaving the papilla of the kidney Collecting duct : Receives drainage from the distal convoluted tubules of several different nephrons; eventually drains into a minor calyx Detrusor muscle : Wall of the bladder Diuresis : The secretion of large amounts of urine Excretion : The process of eliminating wastes from the body External urinary sphincter : Sphincter of skeletal muscle where the urethra passes through the pelvic floor Glomerular filtration rate : Amount of fluid filtered by all the glomeruli of both kidneys Glomerulus : Cluster of capillaries that are part of the renal corpuscles in the nephrons Hilum : Concave notch on medial side of kidney; where blood vessels, the ureters, and nerves enter and leave the kidney Hydronephrosis : Distension of the renal calyces and pelvis with urine caused by an obstruction of the outflow of urine
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Internal urethral sphincter : Ring of smooth muscle at the point where the urethra leaves the bladder that contracts involuntarily to retain urine in the bladder Loop of Henle : U-shaped portion of the renal tubule Micturition : Urination Nephrons : The filtration units of the kidney Oliguria : A urine output of less than 400 ml/day Peritubular capillaries : Network of capillaries surrounding the renal tubules Proteinuria : The presence of protein in the urine; an abnormal finding Renal corpuscles : One of the main components of nephrons, consisting of a glomerulus and Bowman’s capsule, that filters blood plasma Renal cortex : Outer region of the kidney; site of urine production Renal insufficiency : Also called renal failure; results when an extensive number of nephrons have been destroyed through disease or injury, impairing the ability of the kidneys to function Renal medulla : Inner region of the kidney; site of urine collection Renal tubules : Series of tube-like structures within the nephron; where urine is formed Renin : Enzyme released by the kidneys in response to a drop in blood pressure that causes the conversion of angiotensinogen into angiotensin I Renin-angiotensin-aldosterone system : Chain of events responsible for maintaining blood pressure and, therefore, a steady glomerular filtration rate Specific gravity : Measurement that indicates the amount of solid matter in a liquid Trigone : A triangular-shaped, smooth area on the floor of the bladder formed by the openings for the two ureters and the urethra Tubular resorption : Process whereby chemicals are removed from filtrate in the renal tubules and returned to the blood Tubular secretion : Process whereby chemicals are added to the filtrate in the renal tubules Ureters : Muscular tubes connecting the renal pelvis of each kidney with the bladder Urethra : Small tube that conveys urine away from the bladder and out of the body Urinalysis : An examination of the characteristics of urine Urinary bladder : Collapsible muscular sac that stores urine
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help

Related Documents

Lab 17 - Digestive System III.pdf
Lab 13 - Skin.pdf
A&P Exam 2 Study Guide.docx
ANATOMY ASSIGNMENT # 1.docx
Anatomy and Physiology EXAM #4 Study Guide.docx
BIOL251 Exam 3.pdf
A&P EXAM 3 REVIEW GUIDE. 2023.docx
Copy of A&P FINAL EXAM STUDY GUIDE.docx
A&P EXAM 4 REVIEW GUIDE. 2023.docx
A&P EXAM 1 REVIEW GUIDE. 2023.docx
A&P EXAM 2 REVIEW GUIDE. 2023.docx
A&P Assignment #4.pdf