Motility Of The Gut

Question 1

What is the motility of the gut dependent on?

Answer 1

Smooth muscle
Enteric nervous system
Autonomic nervous system
Hormones

Question 2

What are the factors that control GI motility?

Answer 2

Slow waves - basal electrical rhythm and pacemaker cells
Neural control - autonomic and enteric
Hormonal - endocrine and local

Question 3

How does neural control effect GI motility?

Answer 3

Autonomic:
Parasympathetic (vagus nerve); excitatory via ACh and inhibitory via VIP,ADP
Sympathetic; inhibitory via adrenaline

Enteric

Question 4

How does the parasympathetic nervous system affect the motility of the gut?

Answer 4

Via the vagus nerve is is inhibitory via VIP and ADP, and excitatory via ACh

Question 5

How does the sympathetic nervous system affect the motility of the gut?

Answer 5

Inhibitory via adrenaline

Question 6

How does hormonal control affect the motility of the gut?

Answer 6

Endocrine: via gastric, CCK, motilin
Locally: via paracrine or neurocrine action

Question 7

What are the muscle layers of the stomach? Superficial to deep

Answer 7

Oblique muscle layer
Longitudinal muscle layer
Circular muscle layer

Question 8

What are the folds in the inner lining of the stomach called?

Answer 8

Rugae

Question 9

How is the pressure in the stomach kept constant while ingestion occurs?

Answer 9

Plasticity of the smooth muscle in the walls of the stomach allows its volume to increase

Question 10

How is gastric emptying regulated?

Answer 10

Neural enterogastric reflex and hormonal mechanisms inhibit gastric secretions and duodenal filling

Question 11

At what speed does carb heavy chyme move through the stomach compared to lipid rich chyme

Answer 11

Carb laden chyme moves quicker than lipid rich chyme as it requires more time + bile salts

Question 12

What is the hormonal negative feedback loop that means that fatty chyme causes a decrease in the rate of stomach emptying?

Answer 12

Fatty chyme in duodenum
Causes
Duodenal enteroendocrine cells secrete secretin, CCK, GIP
Which causes
Decreased contractile force and rate of stomach emptying

Question 13

What does secretin do

Answer 13

Stimulates HCO3- secretion, inhibits stomach activity

Question 14

What is CCK

Answer 14

Cholecystokinin

Stimulates gall bladder contraction + emptying, inhibits stomach activity

Question 15

What does cholecystokinin do?

Answer 15

Stimulates gallbladder contraction and emptying, inhibits stomach activity

Question 16

What is GIP

Answer 16

Gastric inhibitory peptide

Inhibits gastric contractions

Question 17

What does gastric inhibitory peptide do?

Answer 17

Inhibits gastric contractions

Question 18

What does motilin do

Answer 18

Increases gastric and intestinal motility

Question 19

What is the neural negative feedback loop that means that fatty chyme causes a reduction in stomach emptying?

Answer 19

Fatty chyme
Causes
Stretch receptors/chemoreceptors to
1) via short reflexes in enteric neurons
2) via long reflexes in CNS (increase SNS, decrease PSNS)
To reduce contractile force and rate of stomach emptying