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Questions and Answers
What is digestion?
The process whereby food is broken down into smaller parts, chemically changed, and moved through the gastrointestinal system.
Which of the following organs is responsible for the temporary storage of food?
What are the enzymes found in gastric juices?
Hydrochloric acid, pepsin, and mucus.
Which hormone causes the pancreas to release sodium bicarbonate?
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The small intestine is where the majority of absorption occurs.
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What is the primary function of villi in the small intestine?
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What is metabolism?
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Which cycle involves the complete oxidation of carbohydrates, proteins, and fats?
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Match the following digestive organs with their functions:
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The passage of nutrients into the blood or lymphatic system is called ______.
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Study Notes
Objectives
- Understand digestion, absorption, and metabolism processes.
- Identify digestive system organs and their functions.
- Recognize enzymes and digestive juices secreted by each organ and gland.
- Learn to calculate basal metabolic rate (BMR).
Digestion Overview
- Digestion breaks down food into smaller parts for absorption.
- Involves mechanical breakdown (chewing) and chemical changes (hydrolysis).
- Enzymes act as catalysts to speed up chemical reactions without changing.
Digestion Process
- Mouth: Initial digestion occurs; teeth break down food mixed with saliva.
- Esophagus: Muscular tube connecting mouth to stomach; utilizes peristalsis and gravity to move food, regulated by the cardiac sphincter.
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Stomach: Temporary food storage; mixes food with gastric juices for breakdown and regulates chyme release.
- Gastric Juices: Composed of hydrochloric acid, pepsin, and mucus; includes rennin and gastric lipase in children.
Small Intestine Digestion
- Divided into three sections: duodenum, jejunum, ileum.
- Hormones such as secretin and cholecystokinin regulate digestive juice and bile release.
- Bile: Produced in the liver, stored in the gallbladder; emulsifies fats for absorption.
Enzymes in Small Intestine
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Pancreatic Enzymes:
- Proteases: Break down proteins (e.g., trypsin, chymotrypsin).
- Amylase: Converts starches to simple sugars.
- Lipase: Breaks down fats into fatty acids and glycerol.
- Intestinal enzymes produced include lactase, maltase, and sucrase for sugar conversion; peptidases for protein reduction to amino acids.
Large Intestine Functions
- Comprises cecum, colon, and rectum.
- Absorbs water and salts from undigested food.
- Collects volatile fatty acids for energy.
- Digested food progresses through colon sections (ascending, transverse, descending, sigmoid) to anal canal for excretion.
Absorption Overview
- Nutrients must be in simplest form (simple sugars, amino acids, fatty acids, glycerol) to be absorbed.
- Primarily occurs in the small intestine via villi, which increase surface area for nutrient absorption.
Absorption in the Intestines
- Small Intestine: Villi absorb nutrients from chyme, transferring them to the bloodstream; water absorbed throughout the gastrointestinal tract.
- Large Intestine: Protects colon from digestive juices; synthesizes vitamins B and K, absorbs water, and collects food residue for fecal excretion.
Metabolism Overview
- Transforms absorbed nutrients into energy at the cellular level via aerobic (with oxygen) and anaerobic (without oxygen) metabolism.
- Nutrients are transported by blood to body cells for energy usage.
Metabolic Processes
- Krebs Cycle: Completes oxidation of carbohydrates, proteins, and fats.
- Anabolism: Utilizes energy from oxidation to synthesize new compounds.
- Catabolism: Breaks down compounds during metabolism, regulated primarily by hormonal secretions from the thyroid gland.
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Description
Test your knowledge on the processes of digestion, absorption, and metabolism. This quiz covers the organs involved in the digestive system, their functions, and the enzymes secreted by each organ. Additionally, you'll learn to calculate your basal metabolic rate (BMR).
