Digestion

Question 1

Organs of the GI Tract

Answer 1

Organs include oral cavity, esophagus, stomach, small intestine, large intestine.
Accessory organs include salivary glands, liver, gallbladder, and pancreas.

Question 2

Mechanical Processes

Answer 2

Teeth, tongue, and muscles

Question 3

Chemical Processes

Answer 3

Enzymes (-ases) play the central role in chemical digestion

Question 4

Structure Dictates Function

Answer 4

Digestive organs have unique structures and environments to support different functions of the digestion process.

Question 5

Mouth

Answer 5

Mechanical digestion = increases surface area of food.
Chemical digestion = salivary amylase (CHO) and lingual lipase (fat).
Saliva triggers taste and provides protection.

Question 6

Esophagus

Answer 6

Mechanical digestion = moves and mixes food via peristalsis.
Some chemical digestion continues.

Question 7

Stomach

Answer 7

Mechanical digestion = mixes and moves food.
Chemical digestion = eating triggers the release of the hormone gastrin which stimulates the release of gastric acid (~1/5L/day).

Question 8

Gastric Acid

Answer 8

Contains HCl, KCl, and NaAl.
HCl denatures proteins, kills bacteria and activates pepsin and gastric lipase.
Pepsin digests proteins into smaller polypeptides.
Gastric lipase promotes the action of pancreatic lipase and plays a role in lipid digestion.
Mucus to protect stomach.

Question 9

Protein Structures and Digestion

Answer 9

HCl denatures the quaternary structure of a protein.
Activates pepsin which breaks down proteins into long chains of amino acids (ie. polypeptides).
Pepsin works in the stomach while trypsin and peptidases work in the duodenum.

Question 10

Small Intestine (Duodenum, Jejunum, and Ileum)

Answer 10

Mechanical digestion = moves/mixes chyme.
Chemical digestion = different enzyme for each macronutrient
Majority of absorption.

Question 11

Small Intestine Duodenum

Answer 11

Chyme in the duodenum…
-fat and protein stimulate CCK
-CCK causes gallbladder to contract
-gallbladder secretes bile

Question 12

Gallbladder

Answer 12

Bile emulsifies fat by breaking down fat into small droplets (micelles), and enables lipases to digest triglycerides to mono and diglycerides.
Bile contains bile salts (lecithin (phospholipids), cholesterol) and electrolytes (sodium, potassium, chloride, and calcium).

Question 13

Small Intestine: Duodenum and Pancreas

Answer 13

Bicarbonate to neutralize acidic chyme.
Amylase secreted to breakdown CHO.
Lipase secreted to breakdown fat.
Proteases secreted to breakdown protein.

Question 14

Pancreas secretes…

Answer 14

Pancreatic amylase, lipase and protease.

Question 15

Large Intestine

Answer 15

Moves non-digestible food material fibre, water, and bacteria.
Proteins and amino acids fermented by gut bacteria.
Absorption of water creates a semisolid mass