PhysiologyLesson 7 of 7 in the course The Digestive System

Chemical Digestion and Intestinal Absorption of Nutrients

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Chemical digestion uses enzymes to break large food molecules into smaller units that can be absorbed through the intestinal lining. This lesson introduces hydrolysis and follows the digestion of carbohydrates, proteins, lipids, and nucleic acids.

Food contains large molecules, including starches, proteins, triglycerides, and nucleic acids. Most are too large to pass through the epithelial cells lining the alimentary canal. Digestive enzymes catalyze reactions that split these molecules into smaller products.

All flashcards

What is hydrolysis in digestion?
Hydrolysis is an enzyme-assisted reaction in which water is used to break bonds in large food molecules, producing smaller subunits.
What does pancreatic amylase do?
It digests starch in the small intestine into smaller carbohydrate fragments, including maltose and α-dextrins.
What are the products of sucrose digestion?
Sucrase splits sucrose into glucose and fructose.
Where does protein digestion begin, and what enzyme starts it?
Protein digestion begins in the stomach, where pepsin breaks proteins into smaller peptides.
How are DNA and RNA initially digested?
Pancreatic deoxyribonuclease digests DNA and ribonuclease digests RNA, producing nucleotides.

Quiz questions

  1. How do glucose and galactose enter intestinal epithelial cells?Answer: By co-transport with sodium ions
  2. What do enterocytes package long-chain lipid products into for transport?Answer: Chylomicrons
  3. Where do chylomicrons enter the villi after leaving intestinal epithelial cells?Answer: Lymphatic capillaries called lacteals
  4. Where is the intrinsic factor–vitamin B₁₂ complex taken up?Answer: At receptors in the terminal ileum
  5. How does the sodium-potassium pump support intestinal nutrient co-transport?Answer: It uses ATP to maintain sodium and potassium gradients.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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