ANATOMY AND PHYSIOLOGY
ANATOMY AND PHYSIOLOGY
17th Edition
ISBN: 9781630180928
Author: OpenStax
Publisher: OPENSTAX C
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Chapter 23, Problem 1ILQ

By clicking on this link (http://openstaxcollege.org/l/fooddigestion) , you can watch a short video of what happens to the food you eat as it passes from your mouth to your intestine. Along the way, note how the food changes consistency and form. How does this change in consistency facilitate your gaining nutrients from food?

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Summary Introduction

To analyze:

The changes in consistency of food down the alimentary canal facilitate gaining nutrients from it.

Introduction:

Digestion is the act of breaking down of food into smaller molecules, by physical and chemical means, to release the nutrients present in them and render it in an absorbable form.

Explanation of Solution

The alimentary canal is aptly designed to convert complex food into simpler forms. This conversion not only breaks down food but also helps to extract the nutrients efficiently from all food that is consumed.

The physical, as well as chemical digestion process, begins right away in our mouth. The chewing of food called mastication mechanically shears the large chunks of food to smaller pieces. It then mixes with saliva to make it into a semi-solid paste called bolus that is easy to swallow. The salivary amylase marks chemical digestion of food by acting on starch. The water hydrates and dissolves much of the food. The mucus lubricates the food for swallowing.

As the food moves down the esophagus it reaches the stomach where the churning action continues to physically shear the bolus further to even smaller particle size. The acid and enzymes produced in the stomach chemically act on food to convert complex molecules into simpler forms. These processes convert the bolus to a form that is more fluid-like called the chyme.

Chyme moves down to the small intestine. The duodenum is the region of major chemical digestion with a host of enzymes acting on the chyme. Physical digestion occurs by the process of segmentation.

Finally, the small molecules in the form of glucose (from sugars), fatty acids and glycerols (from lipids and fats), amino acids (from proteins) and nucleic acids (from nucleoproteins) are released from food. Along with these minerals, electrolytes and vitamins are also rendered free for absorption in the small intestine. The continuous backlash movements along the microvilli on intestinal lumen help in absorption of all these nutrient molecules released from the food.

Had these series of processes to bring about a change in the consistency of ingested food not occurred, the food as a source of nutrients would have been meaningless.

Conclusion

Thus a change in consistency of food from largely sized bites to chewed semi-solid paste (bolus) and then to a fluid-like (chyme) consistency helps in both the movement of food down the alimentary canal and finally the absorption of their nutrients in the intestines.

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Chapter 23 Solutions

ANATOMY AND PHYSIOLOGY

Ch. 23 - Which of these processes occurs in the mouth?...Ch. 23 - Which of these processes occurs throughout most of...Ch. 23 - Which of the following stimuli activates sensors...Ch. 23 - Which of these statements about reflexes in the GI...Ch. 23 - Which of these ingredients in saliva is...Ch. 23 - Which of these statements about the pharynx is...Ch. 23 - Which structure is located where the esophagus...Ch. 23 - Which phase of deglutition involves contraction of...Ch. 23 - Which of these cells secrete hormones? parietal...Ch. 23 - Where does the majority of chemical digestion in...Ch. 23 - During gastric emptying, chyme is released into...Ch. 23 - Parietal cells secrete ________. gastrin...Ch. 23 - In which pail of the alimentary canal does most...Ch. 23 - Which of these is most associated with villi?...Ch. 23 - What is the roLe of the small intestines MALT?...Ch. 23 - Which part of the large intestine attaches to the...Ch. 23 - Which of these statements about bile is true?...Ch. 23 - Pancreatic juice ________. deactivates bile. is...Ch. 23 - Where does the chemical digestion of starch begin?...Ch. 23 - Which of these is involved in the chemical...Ch. 23 - Where are most fat-digesting enzymes produced?...Ch. 23 - Which of these nutrients is absorbed mainly in the...Ch. 23 - Explain how the enteric nervous system supports...Ch. 23 - What layer of the alimentary canal tissue is...Ch. 23 - Offer a theory to explain why segmentation occurs...Ch. 23 - It has been several hours since you last ate....Ch. 23 - The composition of saliva varies from gland to...Ch. 23 - During a hockey game, the puck hits a player in...Ch. 23 - What prevents swallowed food from entering the...Ch. 23 - Explain the mechanism responsible for...Ch. 23 - Describe the three processes involved in the...Ch. 23 - Explain how the stomach is protected from self...Ch. 23 - Describe unique anatomical features that enable...Ch. 23 - Explain how nutrients absorbed in the small...Ch. 23 - Why is it important that chyme from the stomach is...Ch. 23 - Describe three of the differences between the...Ch. 23 - Why does the pancreas secrete some enzymes in...Ch. 23 - Describe the location of hepatocytes in the liver...Ch. 23 - Explain the role of bile salts and lecithin in the...Ch. 23 - How is vitamin B12 absorbed?
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