Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

23. The Digestive System

Introduction to the Digestive System

Anatomy & Physiology

23. The Digestive System

Introduction to the Digestive System

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Problem 8

Textbook Question

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.