BSI 2 Lecture 64: Mouth, Esophagus, and Stomach

Question 1

What is the composition of saliva from the parotid, submandibular, and sublingual glands?

Answer 1

99.5% water and 0.5% solutes

Question 2

What makes up the 0.5% solute?

Answer 2

1. lingual lipase
2. salivary amylase
3. ions
4. mucus
5. IgA
6. bacterial lysozyme

Question 3

What is lingual lipase?

Answer 3

A digestive enzyme that works on triglycerides

Question 4

Where is lingual lipase activated?

Answer 4

In the stomach

Question 5

What is salivary amylase?

Answer 5

A digestive enzyme that acts on carbohydrates

Question 6

Does each salivary gland secrete the same proportion of water and solutes?

Answer 6

No

Question 7

What stimulates the salivation?

Answer 7

parasympathetic nervous system

Question 8

What happens to food in the mouth?

Answer 8

1. Begins to dissolve in saliva
2. salivary amylase digests starch
3. Food is reduced to bolus

Question 9

What happens in the esophagus?

Answer 9

Peristalsis pushes food down by coordinated contractions . No further digestion or absorption takes place.

Question 10

What happens in the stomach?

Answer 10

1. Bolus is turned into chyme
2. Pepsinogen is activated to pepsin by HCl and digests proteins
3. Lingual lipase is activated and breaks down fats

Question 11

What is absorbed in the stomach?

Answer 11

water, ions, short chain fatty acids, certain drugs, and alcohol

Question 12

What types of cells are in the gastric glands?

Answer 12

1. Mucous cells
2. Parietal cells
3. Chief Cells
4. G cells
5. D cells
6. ECL cells

Question 13

What do mucous cells do?

Answer 13

secrete a mucous that prevents digestion of the cell wall

Question 14

What do parietal cells do?

Answer 14

secrete HCl and intrinsic factor

Question 15

What is the function of HCl?

Answer 15

1. kill microbes
2. denature proteins
3. activate pepsinogen
4. stimulate secretion of hormones that promote flow of bile and pancreatic juice
5. allow for absorption of some drugs

Question 16

What is HCl secretion stimulated by?

Answer 16

1. acetylcholine
2. gastrin
3. histamine

Question 17

What is HCl secretion inhibited by?

Answer 17

1. somatostatin
2. prostaglandins
3. CCK (cholecystokinin)

Question 18

What are the function of vitamin B12?

Answer 18

1. coenzyme in amino acid metabolism
2. stimulates erythropoiesis
3. energy production
4. normal functioning of nervous system
5. folate metabolism

Question 19

What are the signs and symptoms of vitamin B12 deficiency?

Answer 19

1. anemia
2. fatigue
3. depression
4. poor memory
5. neurological abnormalities
6. GI symptoms

Question 20

How is B12 absorbed?

Answer 20

Gastric acids release B12 from foods and R proteins bind. Pancreatic enzymes degrade the R proteins in the duodenum and intrinsic factor binds, the intrinsic factor/B12 complex is absorbed in the distal ileum via receptor-mediated endocytosis

Question 21

What is a side function of intrinsic factor?

Answer 21

It protects B12 from being catabolized by intestinal bacteria

Question 22

What do chief cells do?

Answer 22

Secrete pepsinogen and gastric lipases

Question 23

How can pepsinogen be activated?

Answer 23

By contact with other active pepsin molecules or HCl

Question 24

What do G cells do?

Answer 24

Secrete gastrin into the bloodstream

Question 25

What does gastrin do?

Answer 25

1. stimulate parietal cells, chief cells, and ECL cells
2. increases motility
3. relaxes pyloric sphincter
4. increases activity of stomach

Question 26

What do D cells do?

Answer 26

Secrete somatostatin

Question 27

What do ECL cells do?

Answer 27

Secrete histamine