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Unit 6 > Physio > Flashcards

Flashcards in Physio Deck (23):
1

What are the 4 GI peptide hormones?

gastrin, secretin, CCK, glucose-dependent-inhibitory peptide (GIP)

2

Gastrin

-secreted by G cells of tummy (antrum)
-stomach distention/vagal stimulation via GRP (gastrin releasing peptide) cause secretion
-increase gastric H+ secretion (directly on parietal cell for HCl and indirectly ECL cell for HA)
-peptide hormone

3

cholecystokinin

-secreted by I cells of duodenum/jejunum
-secreted in response to fats
-increase gallbladder contraction, pancreatic enzyme/bicarbonate secretion
-decreases gastric emptying
-peptide hormone

4

secretin

-secreted by S cells of duodenum
-secreted when chyme leaves tummy
-increases bicarb/pancreatic fluid sectretion
-inhibits gastrin (therefore, stops acidic secretions), stops gastric emptying
-peptide hormone

5

glucose-dependent insulinomic peptide (GIP)

-secreted by K cells of duodenum/jejunum
-secreted in response to fat/carbs
-stimulates insulin secretion from pancreas
-inhibits HCl secretion by parietal cells
-peptide hormone

6

What does VIP do?

-neurocrine of mucosa/smooth muscle
-relaxes smooth muscle
-increases intestinal secretions
-increases pancreatic secretions

7

What are the GI paracrines?

somatostatin, serotonin, histamine

8

serotonin

-enterochromaffic cells of intestine
-respond to distension by exciting ENS to increase motility and secretions

9

somatostatin

-D cells of tummy produce it
-inhibits pancreatic and gastric secretions, motility
-can be endocrine or paracrine

10

histamine

-released by EC-like cells in tummy
-stimulates HCL secretion (H2 receptors)

11

mucus neck cells, cardiac glands (these only near esophagus)

-secrete mainly mucus
-in antrum of tummy

12

peptic (chief) cells

-secrete pepsinogen (cleaved to pepsin at low pH) and gastric lipase
-in body of tummy

13

parietal (oxyntic, acid-forming) cells

-secrete intrinsic factor (cyanocobalamin reab. in ileum) and HCl
-in body of tummy

14

HCO3-/Cl- exchanger (no energy!!)

bicarb from carbonic anhydrase sent to blood, Cl- enters from blood

15

H+/K+ ATPase

H+ from carbonic anhydrase into tummy lumen (digestion), K+ into cell

16

What does prolonged vomiting cause?

hypokalemia (kidney response), alkalosis (lost HCl), dehydration (lost volume/H2O)

17

What stimulates acid secretion?

histamine, vagus, gastrin, caffeine, insulin, stress

18

What inhibits acid secretion?

somatostatin, GIP (gastric inhibitory peptide), secretin, glucose insulinotropic peptide

19

Whom does the vagus stimulate?

-parietal cells, ECL cells, D cells (directly via ACh)
-G cells (via GRP)
-D cells (inhibits somatostatin via ACh)

20

What's in saliva normally?

-hypotonic (less osmolarity than plasma)
-alpha-amylase, lingual lipase
-high K+, high bicarb
-low Na+, low Cl-
-uses Cl-/bicarb, K+/H+, Na+/H+ transporters

21

What about high flow rates?

-less time for ion reabsorption
-bicarb higher, K+ low
-saliva more like plasma

22

What about low flow rates?

-more time for ion reabsorption
-less Na+/Cl-
-more K+, lower bicarb

23

What's in pancreatic secretions?

-lots of bicarb to neutralize acidic chyme (CCK/secretion increase bicarb secretion)
-isotonic secretion