Digestion 1

Question 1

Main role of the mouth, pharynx/esophagus, stomach, small intestine, large intestine, and rectum/anus

Answer 1

Mouth- Chew and moisten food. Has lingual and salivary amylase to break down starches.

Pharynx/esophagus- Transport food to the stomach.

Stomach- Mechanical disruption and mixing of food with gastric juices. No absorption, only breaks stuff down.

Small intestine- Chemical digestion and absorption of nutrients, electrolytes and water.

Large intestine- Absorption of electrolytes and water

Rectum/anus- Storage and elimination of undigested material.

Question 2

What 3 things does gastrin hormone do?

Answer 2

• Release more gastric juice, which increases gastric motility.
• Relax pyloric sphincter
• Constrict esophageal spinster so that you don’t have reflex

Question 3

What 2 things do chief cells secrete?

Answer 3

1. Pepsinogen, which is a precursor of pepsin, attacks proteins. Cleaved by HCl from parietal cells.
2. Gastric lipase. Attacks lipids.

Question 4

Which three things can make more stomach acid by activating parietal cells?

Answer 4

Neural activity
Histamine secretion
Gastrin secretion

Question 5

What inhibits acid production?

Answer 5

Somatostatin secretion.

Question 6

What kind of receptor does histamine bind to?

Answer 6

G couple

Question 7

What causes ulcers?

Answer 7

Bacteria. Ex: H Pylori

Question 8

3 phases of digestion

Answer 8

1. Cephalic phase. 30% response.
2. Gastric phase. 60% response
3. Intestinal/pyloric phase. 10%

Question 9

How does the cephalic phase influence digestion?

Answer 9

30%.
Receptors for sight, smell, and taste of food are activated. Stimulates hypothalamus, medulla, then vagus. Vagus stimulates parietal cells to release HCl, and gastrin release from G cells.

Question 10

How does the gastric phase influence digestion

Answer 10

60%. Stretch receptors detect distention of stomach. Chemoreceptors detect increased pH of gastric juices.

When food enters the stomach, distention stimulates vasovagal response (responds to stretch, goes back to medulla and tells brain to activate parietal and G cells) to increase gastrin and acid release.
Additionally, protein in the stomach increases gastric acid.

Question 11

How does the contents in the stomach change after eating?

1-1.5 hours after eating:
2 hours after eating:
4 hours after eating:

Answer 11

1-1.5 hours after eating: food starts moving through the pylorus.
2 hours after eating: decrease level of pH/contents/acid secretions and food.
4 hours after eating: all contents gone.

Question 12

How does the intestinal/pyloric phase influence digestion

Answer 12

Stretch receptors detect distention of the duodenum and chemoreceptors detect fatty acids and glucose in duodenum. It makes sure the substances are digested.

Can signal enteroendocrine cells to shut down G cells

Question 13

Enteroendocrine cells

Answer 13

Release CCK and secretin. They both stop peristalsis and secretin stops gastric juice production as well. Inhibitory. Shuts down G cell.

Question 14

Bombesin

Answer 14

Gastrin releasing protein (GRP). Made in the pyloric region. Helps produce more gastrin.

Question 15

Pepsinogen is cleaved at a pH lower than

Answer 15

5. This activates pepsin, which can cleave proteins by splitting interior peptide bonds.

Question 16

Release of chyme into the duodenum is regulated by which two reflexes?

Answer 16

Neural and hormonal

Question 17

When the stomach is full, which organ does it press on? (near the greater curvature)

Answer 17

The pancreas. Has pascinian corpuscles Stimulates pancreas to release bicarbonate.

Question 18

Where is CCK produced and what is its role?

Answer 18

Produced in the small intestine. Relaxes the sphincter of oddi. Inhibits stomach acid secretion and motility.

Results in break down of fatty acids and amino acids in the small intestine.

Question 19

Gastin is produced in which area of the stomach

Answer 19

Antrum

Question 20

The pancreas makes __ hormones and __ enzymes

Answer 20

6 hormones, 8 enzymes +bicarb

Question 21

What is the role of the pancreas secreting pancreatic juice that is rich in bicarbonate?

Answer 21

The bicarbonate increases the pH of the stomach contents as they enter the small intestine. Without, none of the other enzymes would work because they require a pH of 7-8 to work.

Question 22

8 enzymes released by the pancreas + bicarb

Answer 22

Trypsin, chymotrypsin, elastase (break down protein)
Carboxypeptidase (break down protein)
Lipase (breaks down lipids/fats)
Amylase (breaks down polysaccharides)
Ribonuclease, deoxyribonuclease (nucleic acids)
Bicarbonate (neutralizes)