Chapter 21, Problem 1CC

Label the parts of the human digestive system below and indicate the functions of these organs and glands.

Summary Introduction

To label: The parts of human digestive system in the figure given and indicate their functions.

Introduction: Human digestive system consists of gastrointestinal (GI) tract and accessory organs. The gastrointestinal tract is made up of mouth, esophagus, stomach, small intestine, large intestine, and anus. The accessory organs for digestion are liver, pancreas, and gallbladder. Each part of the digestive system moves ingested food through gastrointestinal tract, breaks it into small parts, so that they can be absorbed if needed or expelled out.

Answer to Problem 1CC

Fig. 1 shows the organs and glands of the human digestive system.

Pictorial representation: A labeled diagram showing the various parts of a human digestive system.

Fig.1 Human digestive system

Explanation of Solution

(a)

Correct answer: Oral cavity

Explanation: In a digestive system, the first section is ingestion and chewing of food. This is done by the oral cavity or mouth cavity. It consists of lips, cheek lining, teeth, front part of the tongue, gums, and roof of the mouth. Hence, the correct answer is oral cavity.

(b)

Correct answer: Salivary glands

Explanation: The ingested food moves through gastrointestinal tract by the process known as peristalsis. After chewing, the salivary glands form digestive juice called saliva, which moistens food to easily pass through the esophagus into the stomach. Hence, the correct answer is salivary glands.

(c)

Correct answer: Liver

Explanation: The liver’s function is to produce and secrete a digestive juice known as bile. Bile ducts carry bile from liver to gall bladder for storage, and it helps in digestion of fats. Also, the liver contributes in filtering and purifying the blood. Hence, the correct answer is liver.

(d)

Correct answer: Gall bladder

Explanation: Gall bladder is located below liver and stores bile juice. When fatty food enters the duodenum of the small intestine, the gall bladder squeezes into small intestine through bile ducts. Hence, the correct answer is gall bladder.

(e)

Correct answer: Pancreas

Explanation: Pancreas mainly forms digestive enzymes that are released into small intestine through ducts. These enzymes help in digestion of fats, proteins, and carbohydrates. Hence, the correct answer is pancreas.

(f)

Correct answer: Rectum

Explanation: Rectum is a part of the large intestine that connects the colon to the anus. It receives stool from the colon and accommodates it until it is expelled out through sphincters. Hence, the correct answer is rectum.

(g)

Correct answer: Pharynx

Explanation: Pharynx is also referred as throat in the digestive tract. It receives food from the mouth. It branches into the esophagus and the trachea. The esophagus further takes food to the stomach for digestion, and trachea carries air to the lungs. Hence, the correct answer is pharynx.

(h)

Correct answer: Esophagus

Explanation: After ingestion and chewing of food, the food is pushed to the stomach through peristaltic movement. It is carried through the esophagus. The esophagus is also known as food pipe. Hence, the correct answer is esophagus.

(i)

Correct answer: Stomach

Explanation: Stomach is a digestive organ in the abdominal cavity. It secretes digestive enzymes (breaking of large molecules), mucus (moisten), and hydrochloric acid (protection against microbes) for digestion of ingested food. Hence, the correct answer is stomach.

(j)

Correct answer: Small intestine

Explanation: Small intestine is a coiled structure and secretes digestive juices. It consists of folds that contribute in digestion and absorption of nutrients. Hence, the correct answer is small intestine.

(k)

Correct answer: Large intestine

Explanation: Large intestine consists of cecum, colon, and rectum. It helps in absorption of water from the gastrointestinal tract into the bloodstream. The unused particles are moved further into the rectum for elimination. Hence, the correct answer is large intestine.

(l)

Correct answer: Anus

Explanation: Anus is the last part of the digestive system. It is the external opening at the end of rectum for elimination of feces from the body. Defecation is controlled by two sphincters namely internal and external anal sphincters. Hence, the correct answer is anus.