Monogastric pt 2

Question 1

What is a gut hormone?

Answer 1

• Must be secreted by gut cell and exert effect on another cell
• Endocrine route
• Stimulated by food
• Not dependent on neural control
• Synthetic form must mimic the actions of the native substance

Question 2

What produces gastrin and what is the release stimulus?

Answer 2

G cells, duodenum. Peptides and aa

Question 3

What does gastrin do?

Answer 3

Positive action on parietal cell and HCl secretion

Question 4

What produces secretin and what is the release stimulus?

Answer 4

Duodenal S cells, jejunum; Acid, fat, and protein

Question 5

What does secretin do?

Answer 5

Positive effect on HCO3 secretion negative effect on HCl secretion

Question 6

What produces CCK and what is the release stimulus?

Answer 6

I cells, small intestine and enteric neurons; Fats protein

Question 7

What is the effect of CCK

Answer 7

Positive effect on pancreatic enzyme and insulin secretion, positive effect on bile secretion, satiety factor

Question 8

What produces GIP and what is the release stimulus?

Answer 8

K cells, duodenum and jejunum; Fats and glucose

Question 9

What does GIP do?

Answer 9

Negative effect on gastric secretion and increase insulin secretion

Question 10

What produces motilin and what is the release stimulus?

Answer 10

M cells, duodenum and jejunum; Duodenal pH increase and acetylcholine

Question 11

What does motilin do?

Answer 11

Antral and duodenal MMC, Phase III induction during digestion

Question 12

What are substances that signal via paracrine?

Answer 12

• Somatostatin
• Peptide YY
• Serotonin
• Histamine

Question 13

What secretes serotonin?

Answer 13

Enterochromaffin cells

Question 14

What does serotonin do?

Answer 14

• Stimulate enteric nervous system
• Vagal afferents (gut to brain)
• Enterocyte secretion
• Blood flow

Question 15

What are the two paracrine effects of serotonin?

Answer 15

Enterochromaffin cells pick up hyperosmolality and acidity. Can either:

1. Bind to receptors on sensory afferents
2. Receptors on enterocytes

Question 16

What drug blocks serotonin receptors and prevents nasaue?

Answer 16

Ondansetron

Question 17

What increases the secretion of trophic factors?

Answer 17

Increase feed, increases demand, increases production and secretion of trophic factors

Question 18

What promotes growth on the gastric mucosa?

Answer 18

Gastrin

Question 19

What promotes growth of the intestinal mucosa?

Answer 19

CCK and enteroglucagon

Question 20

What happens to regulatory peptides in cold adaptation?

Answer 20

Increased nutrition for warmth and therefore increased food intake. This increases the regulatory peptides and elongates intestinal villi leading to enhanced absorption

Question 21

Muscle layers of the gut wall facilitate what?

Answer 21

• Propulsion
• Retention
• Physical breakdown of food
• Particle mixing and circulation

Question 22

What is the propulsive movement?

Answer 22

Relationship to transit time/rate (dp/dt)

Question 23

What is a syncytium?

Answer 23

Group of cells in which the protoplasm of one cell is continuous with that adjoining cells

Question 24

What facilitates the protoplasmic continuity between smooth cells?

Answer 24

Gap junctions

Question 25

What is a a gap junction?

Answer 25

2 Connexon. Used for exchange of substances between cells

Question 26

Why are gap junctions so important in propulsion?

Answer 26

• protoplasmic continuity
• Low resistance pathway for ions to move
• Membrane potential changes are coordinated and waves move oral to aboral

Question 27

Do slow waves always result in smooth muscle contraction?

Answer 27

No

Question 28

Slow waves are…

Answer 28

Myogenic. no neural input needed