Ch. 22 The Digestive System

Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook

Amerman 3rd Edition

Ch. 22 The Digestive System

Problem 1

Chapter 22, Problem 1

Trace the pathway that food takes through the entire alimentary canal, from the oral cavity to the anal canal.

Verified step by step guidance

Start with the oral cavity (mouth), where food is ingested. Here, mechanical digestion occurs through chewing (mastication), and chemical digestion begins with the action of salivary amylase breaking down carbohydrates.

Food is then pushed by the tongue into the pharynx and enters the esophagus. The process of swallowing (deglutition) moves the food bolus down the esophagus via peristaltic contractions.

The food bolus passes through the lower esophageal sphincter into the stomach. In the stomach, mechanical digestion continues through churning, and chemical digestion occurs with the secretion of gastric juices, including hydrochloric acid and pepsin, which begin protein digestion.

The partially digested food, now called chyme, moves into the small intestine through the pyloric sphincter. In the small intestine (duodenum, jejunum, and ileum), most digestion and nutrient absorption occur. Enzymes from the pancreas and bile from the liver aid in breaking down fats, proteins, and carbohydrates.

Finally, undigested material passes into the large intestine (colon), where water and electrolytes are absorbed. The remaining waste is compacted into feces and stored in the rectum until it is expelled through the anal canal during defecation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alimentary Canal

The alimentary canal, also known as the digestive tract, is a continuous tube that extends from the mouth to the anus. It includes several key structures such as the oral cavity, esophagus, stomach, small intestine, large intestine, and rectum. Understanding this pathway is essential for comprehending how food is processed and nutrients are absorbed throughout the digestive system.

Digestive Processes

Digestive processes encompass the mechanical and chemical breakdown of food. Mechanical digestion begins in the mouth with chewing and continues in the stomach, while chemical digestion involves enzymes breaking down food into absorbable nutrients. These processes are crucial for transforming food into energy and building blocks for the body.

Absorption and Elimination

Absorption refers to the process by which nutrients from digested food are taken up into the bloodstream, primarily occurring in the small intestine. Elimination is the final stage of digestion, where indigestible substances and waste products are expelled from the body through the anal canal. Understanding these processes is vital for grasping how the body utilizes food and maintains homeostasis.

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Textbook Question

Drugs with anticholinergic side effects block ACh receptors in the peripheral nervous system, including those on digestive organs. Predict the effects such drugs would have on motility and secretion on the specific organs of the digestive system.

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Textbook Question

Which of the following is/are absorbed in the small intestine by the Na+/glucose cotransporter?

a. Glucose

b. Galactose

c. Fructose

d. Both a and b are correct

e. All of the above are correct

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Textbook Question

Mr. Williams presents to your clinic with a complaint of abdominal pain in the right upper quadrant. He says that the pain worsens when he eats, particularly when he eats fatty meals. He has noticed that his stool has been an unusual clay color recently. You perform an ultrasound of his abdomen and find that gallstones are blocking his common bile duct, preventing bile from entering the duodenum.

Why are his symptoms worse when he consumes a high-fat meal? Would you expect his symptoms to worsen or lessen when he consumes a meal consisting only of carbohydrates? Explain.

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