Unit 2 Lecture 26 - Stomach anatomy

Question 1

What are the 4 main parts of the stomach?

Answer 1

• cardia
• fundus
• body
• pylorus

Question 2

What is the sphincter in the stomach?

Answer 2

pyloric sphincter

Question 3

What triggers the stomach to secrete and move fluids and stuff?

Answer 3

a full stomach

Question 4

What does the stomach empty into?

Answer 4

Duodenum of the small intestine

Question 5

What squirts through the pyloric sphincter?

Answer 5

Chyme

Question 6

What is chyme?

Answer 6

acidic juices from the stomach

Question 7

What are the cells in the stomach and what do they secrete?

Answer 7

1. Surface mucous cells - secrete mucous
2. Mucous neck cells - secrete mucous
3. Parietal cells - secrete HCl and intrinsic factor
4. Chief cells - secrete pepsinogen and gastric lipase
5. G cells - secrete gastrin hormone

Question 8

What comes in and out of parietal cells in the stomach?

Answer 8

HCO3- (bicarbonate) goes out of stomach and Cl- goes in

Question 9

What stimulates mechanical digestion in the stomach?

Answer 9

Different intensities of waves

Question 10

What are the 3 intensities of waves and what do they do?

Answer 10

• gentle mixing waves: mix bolus of food with gastric juices -> chyme
• more vigorous waves: move chyme to pyloric region
• intense waves: open pyloric sphincter

Question 11

What are the two forms of chemical digestion in the stomach?

Answer 11

Protein digestion BEGINS and lipid (fat) digestion CONTINUES

Question 12

What is involved in protein digestion in the stomach?

Answer 12

HCl

Question 13

What does HCl do to proteins in the stomach?

Answer 13

• denatures (unfolds) proteins
• kills microbes in food
• activates pepsinogen into pepsin

Question 14

What is pepsin?

Answer 14

an enzyme that breaks peptide bonds between certain amino acids

Question 15

What is involved in lipid digestion in the stomach?

Answer 15

gastric lipase

Question 16

What does gastric lipase do in the stomach?

Answer 16

splits triglycerides in milk fat

Question 17

Where is alcohol absorbed in the body?

Answer 17

Stomach (and sometimes small intestine)

Question 18

What slows the absorption of alcohol in the stomach?

Answer 18

• fat content (slows passage to intestine where its more rapid)
• eating a meal

Question 19

How does food entering the stomach disrupt homeostasis?

Answer 19

Increases

• pH of gastric juices
• stretching of stomach walls

Question 20

What does an increase in pH and stomach stretching stimulate?

Answer 20

chemoreceptors and stretch receptors in stomach

Question 21

What do chemoreceptors and stretch receptors stimulate AND where?

Answer 21

Nerve impulses in the submucosal plexus

Question 22

What do nerve impulses in the submucosal plexus trigger?

Answer 22

• parietal cells to secrete mucous

- smooth muscle to contract more vigorously

Question 23

What happens when the stomach secretes more mucous and contracts?

Answer 23

Increases stomach acidity and mixing -> empties stomach

——> maintains homeostasis

Question 24

Does the stomach have endocrine or exocrine functions?

Answer 24

Endocrine

Question 25

What cells are stimulated due to distention and the presence of food

Answer 25

G cells

Question 26

What do g cells secrete?

Answer 26

gastin

Question 27

What does gastin do?

Answer 27

increases gastric gland secretions and movement of liquids

relaxes pyloric sphincter