GI System 2/3

Question 1

Oral Phase Digestion

Answer 1

• mechanical digestion (chewing)
• digestion of starches (salivary amylase)
• lipid hydrolysis (lingual lipase)

Question 2

Oral Antibacterial Actions

Answer 2

Lysozyme: antibacterial enzyme
Immunoglobulins: antibodies

Question 3

Gastric Phase Digestion

Answer 3

• contractions & gastric acid/secretions digest food
• produces chyme

Question 4

Gastric Phase Protection

Answer 4

• acidic environment destroys pathogens
• mucus & bicarbonate protect stomach lining

Question 5

Gastric Phase Storage

Answer 5

• chyme release into SI is regulated

Question 6

Mucus-Bicarbonate Layer

Answer 6

• Gastric mucous cells secrete bicarboante to neutralize gastric juice (acidic) which protects gastric epithelium

Question 7

Gastric Protein Digestion

Answer 7

pepsinogen is activated by acidic environments, turning into pepsin
- HCL denatures folded proteins
- Pepsin cleaves peptide bonds

Question 8

Gastric Chemical Digestion Overview

Answer 8

Protein - HCL denatures protein, pepsin breaks peptide bonds

Fats - Gastric motility & Gastric Lipase

Carbohydrate - none (salivary amylase is inactivated at low pH

Question 9

Gastric Motility

Answer 9

forms an emulsion of lipids (fat droplets) and gastric lipase

Question 10

Gastric Lipase

Answer 10

hydrolyses triglycerides into monoglycerides and free fatty acids

Question 11

Pariteal Cells

Answer 11

secrete HCL upon acetylcholine stimulation

Question 12

Chief Cells

Answer 12

secrete Pepsinogen/gastric lipase upon ACh stimulation

Question 13

SI Functions: regulation of gastric emptying

Answer 13

chyme release is regulated by what materials enter
- simple carbs increase release
- protein decreases release

Question 14

SI Functions: Secretions

Answer 14

1. Epithelial Cells: mucus, brush border enzymes
2. Pancreas: Bicarbonate, digestive enzymes (pancreatic lipase/protease/amylase)
3. Liver & Gallbladder: Bile

Question 15

SI Functions: Digestion

Answer 15

carbs/proteins/fats

Question 16

SI Lacteals

Answer 16

transport absorbed fat via lympatic system because fats are hydrophobic and need to be packaged at the liver

Question 17

Exocrine Pancreas

Answer 17

• most secretions for digestion are from pancreas
• pancreatic protease/amylase/lipase
• duct cells secrete NaHCO3- to neutralize acidic chyme from the stomach

Question 18

Bilary Secretions

Answer 18

Bile is produced by the liver and stored in the gallbladder
- used to digest and absorb fats

Question 19

Carbohydyrate Digestion

Answer 19

Oral: mechanical by chewing, chemical by salivary amylase

Gastric: mechanical by peristaltic contractions, no chemical

Intestinal: mechanical by segmental contractions, chemical by pancreatic amylase/sucrase/lactase/maltase

Question 20

Protein Digestion

Answer 20

Oral: mechanical by chewing, no chemical

Gastric: mechanical by peristaltic contractions, chemical by pepsin/HCl

Intestinal: mechanical by segmental contractions, chemical by pepsin/trypsin

Question 21

Fat Digestion

Answer 21

Oral: mechanical by chewing

Gastric: mechanical by peristaltic contractions, chemical by gastric lipase/emulsification

Intestinal: mechanical by segemental contractions, chemical by pancreatic lipase/colipase

Question 22

Lipid Transport

Answer 22

requried course emulsification in the stomach (fat droplets) and fine emulsification (micelles) in the small intestine

Question 23

The Large Intestinal Phase

Answer 23

• furthur absorption of water and electrolytes
• environment for microflora
• digests some fiber
• storage of waste in rectum

Question 24

Microflora Functions

Answer 24

1. digest dietary fibre
2. produce vitamin K
3. limit growth & invasion of pathogenic microorganism’s

Question 25

Steatorrhea

Answer 25

undigested fat in feces, sign of intestinal dysfunction