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GIGU > DSA GI Regulatory Substances > Flashcards

DSA GI Regulatory Substances Flashcards

1
Q

What regulate the functions of the GI tract?

A

Hormones, neurocrines, paracrines

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2
Q

What make up Gastrointestinal Peptides?

A

Hormones (released in portal circulation to liver–>systemic–> carried back to target organs)

Paracrines (act locally within same tissue that secretes them)

Neurocrine (synth in neurons of GI, released after AP)

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3
Q

What GI peptides are classified as hormones?

A

Gastrin
CCK (cholecystokinin)
Secritin
GIP

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4
Q

What GI peptide is classified as paracrine?

A

Somatostatin (inhibitory)

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5
Q

What GI peptides are classified as neurocrine?

A

ACh, NE, VIP, NO, GRP, enkephalins, substance P

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6
Q

What criteria must be met to qualify as a GI hormone?

A

1: must be secreted in response to stimulus and carried to distant site via bloodstream
2: fxn has to be independent of neural activity
3: must be isolated, purified, identified, synthesized

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7
Q

Fxn of Gastrin

A

promotes H+ secretion by parietal cells (G cells) in stomach

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8
Q

What is the minimum fragment necessary for gastrin biological activity?

A

C-terminal tetrapeptide

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9
Q

What stimulates secretion of gastrin?

A

Ingestion of food

—> neurocrine GRP released as part of vagal reflex, distention of stomach, Phe and Trp

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10
Q

What inhibits secretion of gastrin?

A
  • low pH of stomach

- Somatostatin

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11
Q

What are the major actions of gastrin?

A
  • stimulates H+ secretion by gastric parietal cells

- stimulates growth of gastric mucosa

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12
Q

Zollinger-Ellison Syndrome

A

gastrin-secreting tumor (gastrinoma, usually in head of pancreas)—> increased H+ secretion, inactivation of pancreatic lipase–> steatorrhea

treat w/ H+ pump inhibitors (omeprazole) among others

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13
Q

Fxn of CCK

A

promote fat digestion and absorption

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14
Q

What is the minimum fragment of CCK necessary for activity?

A

C-terminal heptapeptide

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15
Q

Where are CCK secreted?

A

I cells of deodenal and jejunal mucosa

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16
Q

What stimulates CCK secretion?

A 
fatty acids (not TAGS) and small peptides/amino acids
(tell I cells that you just ingested a meal with fat and protein)
17
Q

What are the 5 actions of CCK?

A

1: contraction of GB to eject bile into SI
2: secretion of pancreatic enzymes (lipase and amulase)
3: secretion of bicarbonate from pancreas
4: growth of exocrine pancreas and GB
5: inhibition of gastric emptying to allow time to digest and absorb

18
Q

What secretes secretin?

A

S cells of duodenum

19
Q

What stimulates secretion of secretin?

A

H+ and fatty acids in lumen of SI (when acidic contents arrive from stomach~pH 4.5)

20
Q

Fxn of secretin

A

promote secretion of pancreatic and biliary bicarbonate

—-> neutralizes H+ so you can digest fat via lipase (pH 6-8)

21
Q

Where is GIP secreted?

A

K cells of duodenal and jejunal mucosa

22
Q

What stimulates GIP secretion?

A

glucose, amino acids, fatty acids

23
Q

Fxn of GIP

A

Stimulation of insulin secretion by pancreatic B cells

inhibition of gastric H+ secretion and emptying

24
Q

Due to its fxn, what is GIP also classified as?

A

Incretin–> GI hormone that promotes secretion of insulin

25
Q

Why is oral glucose utilized more rapidly vs IV glucose?

A

Oral + GIP–> + insulin secretion by pancreatic B cells (and direct method below)

IV + insulin secretion only by direct action on B cells (absorbed glucose on B cells)

26
Q

Fxn of motilin

A

not a true hormone, increase GI motility and + myoelectric complexes

27
Q

Incretins

A

GIP, glucagon-like peptide-1 (GLP-1)

28
Q

What secretes somatostatin?

A

D cells of stomach mucosa, hypothalamus, delta cells of endocrine pancreas

29
Q

What simulates somatostatin secretion?

A

low stomach lumen pH

30
Q

Fxn of somatostatin

A

inhibits secretion of GI hormones, gastric H+ secretion

31
Q

Fxn of histamine

A

+ H+ secretion

32
Q

Where is the satiety center?

A

VPN of hypothalamus

inhibits appetite even in presence of food

33
Q

Where is the feeding center?

A

lateral hypothalamic area

34
Q

Fxn of leptin

A

secreted by fat cells, decreases appetite, increases energy expendature

35
Q

Fxn of ghrelin

A

secreted by gastric cells before ingestion of meal, increases appetite

36
Q

What cells secrete histamine?

A

enterochromaffin-like cells in stomach

37
Q

What cells produce pepsinogen?

A

Chief cells in stomach

GIGU (37 decks)

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