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W/Physiology > Topic 6.1 > Flashcards

Topic 6.1 Flashcards

1
Q

What are the 2 big plexuses of GI system and their fct?

A
  • Myenteric (Auerbach) : for motility

- Submucosal (Meissner) : for digestion

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2
Q

On top of Ach and NE, what are some molecules that can regulate GI? (3 examples per term)

A
  • Non peptides : 5HT3, ATP, NO

- Peptides : VIP, substance P, opioids

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3
Q

What are the 2 main effects of the sympathetic system on GI?

A

1 - circulatory : causes contraction of vessels

2 - NE can close / contract the sphincters and limit bowel movement

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4
Q

What is the gastroenteric reflex?

A

enhanced peristalsis

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5
Q

What mediates the gastroenteric reflex?

A

Myenteric plexus and gastrin

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6
Q

What is the gastroileal reflex?

A

stimulation of peristalsis in the ileum + opening of ileocecal sphincter after a meal

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7
Q

What facilitates the gastroileal reflex?

A

Gastrin

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8
Q

What are the gastrocolic and duodenocolic reflexes?

A

Distention of the stomach / duodenum stimulates evacuation of the colon. Blunted in adults

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9
Q

What transmits the gastrocolic / duodenocolic reflex?

A

The ANS

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10
Q

What is the enterogastric reflex?

A

distention and irritation of the small intestine results in suppression of secretion and motor activity in the stomach

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11
Q

What mediates the enterogastric reflex?

A

the ENS and ANS

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12
Q

What is the colonocolic reflex?

A

Propels stool caudally by proximal muscle constriction + distal muscle distention

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13
Q

What mediates the colonocolic reflex?

A

the myenteric plexus

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14
Q

What are the rectocolic (defecation) reflexes?

A
  • Intrinsic reflex mediated my myenteric plexus

- Parasympathetic defecation reflex mediated by the pelvic nerve

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15
Q

3 types of neurons of ENS?

A
  • Afferent neuron
  • Interneuron
  • Efferent neuron
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16
Q

What type of stimuli can activate the ENS?

A
  • mechanical / chemical

- local / external (smell)

17
Q

What is paraneoplastic syndrome?

A

misproduction of regulatory molecules due to cancer / tumour (called neoplasm)

18
Q

7 molecules involved in endocrine regulation

A
  • CCK (cholescystokinin)
  • Gastrin
  • Secretin
  • GIP (gastric inhibitory peptide)
    (- Ghrelin)
    (- Aldosterone)
    (- Calcitriol)
19
Q

What produces CCK?

A

The i-cells in the duodenum

20
Q

What is CCK useful for? (3)

A
  • increases pancreatic juice secretion (enzymes + bicarbonate)
  • decrease gastric emptying
  • contraction of gallbladder
21
Q

What produces Gastrin?

A

G cells of stomach and small intestine

22
Q

What is gastrin useful for? (2)

A
  • Gastric acid secretion

- Growth of gastric mucosa

23
Q

What is secretin useful for?

A
  • pancreatic juice secretion based on acid content of the duodenum
24
Q

What produces secretin?

A

S-cells

25
Q

What produces GIP?

A

K-cells of the intestines

26
Q

What are the roles of GIP?

A
  • increase of insulin secretion

- inhibition of gastric emptying (gastric content released in intestines)

27
Q

What molecules is GIP a part of?

A

Incretins

28
Q

What produces ghrelin?

A

P/D1 cells of the stomach, when it’s empty to signal hunger

29
Q

What is the role of aldosterone in GI?

A

regulation of epithelial Na, K absorption in colon

30
Q

What is the role of calcitriol in GI?

A

enhances intake of Ca2+ from the lumen

31
Q

What are the 3 paracrine molecules involved in paracrine regulation of GI?

A
  • Serotonin
  • Histamine
  • Somatostatin
32
Q

What releases serotonin?

A

enterochromaffin cells

33
Q

When is serotonin released by EC cells?

A

when there is mechanical stretch of the GI wall

34
Q

What is the role of histamine in GI?

A

increases gastric acid secretion

35
Q

What releases histamine in GI? (2)

A
  • ECL cells (enterochromaffin like cells)

- mast cells

36
Q

What is the effect of somatostatin on GI?

A
  • General inhibitory effect : decrease gastric acid secretion, decrease nutrient absorption
37
Q

What releases somatostatin?

A

the D cells

W/Physiology (31 decks)

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