Digestion

Question 1

Exocrine glands
What are they composed of?

Answer 1

Secrete on the surface of the body or into the lumen of the gut
Acinus (cells with complex RER, Golgi, mitochondria) (tight junctions) (basement membrane) duct

Question 2

Why do we have an acidic environment in our stomach?
How is the pH increased?

Answer 2

• helps in food digestion
• optimal conditions for enzymes ( pepsinogen converted to pepsin)
• kills pathogens

Mucus lines the stomach to prevent its damage from low pH.
Bicarbonate ions in pancreatic juice nautralizes the acid

Proton pumps in parietal cells are inhibited by drugs

Question 3

List features of the villi

Answer 3

• intestinal glands that release digestive juices
• lacteal to absorb lipids into the lymphatic system
• rich capillaries
• single layer epithelium
• microvilli
• membrane proteins that help with nutrient transport (many mitochondria produce ATP for active transport)

Question 4

what is dietary fibre?

Answer 4

indigestable materials such as cellulose or lignin
the rate of transit in large intestine is faster when there is more fibre
fiber adds bulk and absorbs water
no constipation
no bowel cancer
healthy weight

Question 5

What causes stomach ulcers?

Answer 5

Helicobacter pylori
damages mucus layer (inflammatory response of goblet cells that stop producing mucus) exposing epithelial cells to stomach acid causing ulcers

Question 6

What causes diarrhea and dehydration?

Answer 6

cholera toxin
ion pumps pump ions into the intestinal lumen, water drawn from cells by osmosis which results in diarrhea and dehydration