Oxyntic and pyloric glands, their cells, their secretions

Question 1

Oxyntic glands

Answer 1

D cells (somatostatin) 
Chief cells (pepsinogen)
Parietal cells (HCL, intrinsic factor) 
mucous neck cells 
enterochromaffin cells (histamine secreting)

Question 2

Pyloric glands

Answer 2

D cells (somatostatin)
G cells (gastrin) 
enterochromaffin cells (histamine secreting)

Question 3

mechanism of HCL secretion by parietal cells

apical domain transporters
internal activity
basal membrane transporters

Answer 3

apical: H-K exchanger ATPase, bringing K in, and pushing H into the lumen

internally, carbonic anhydrase combines CO2+H2O to form H and HCO3

H is then taken BACK out into the lumen by the H-K exchange ATPase

basal side:

Na/K ATPase

HCO3/CL exchanger, brings Cl into the cell from blood

Question 4

omeprazole targets

Answer 4

the H-K ATPase exchanger on the apical membrane of the parietal cell

it secretes H in exchange for K; K is brought from the blood via Na/K ATPase

Cl is brought into the cell by pumping HCO3 into the blood

Cl diffuses out of the apical part of the cell, following H

H and Cl form HCL

omprazole targets the H secretor so HCL cant form in the lumen

Question 5

what kind of “tide” do we find near parietal cells?

Answer 5

the “alkaline tide” across the basal membrane as HCO3 is reabsorbed into the blood

Question 6

Histamine

Answer 6

a paracrine

released by enterochromaffin cells in response to ACh and gastrin hormone

histamine stimulates parietal cell HCL secretion

binds to H2 receptors on parietal cells

Question 7

what receptors does histamine bind to on the parietal cells?

Answer 7

H2 receptors

Question 8

what blocks the receptors that histamine acts on?

Answer 8

cimetidine blocks H2 receptors

Question 9

histamine — H2 receptor —>

Answer 9

cAMP —> H secretion through H/K ATPase

Question 10

ACh

Answer 10

stimulates HCL secretion

released from Vagus

Question 11

ACH from the vagus binds to the ____ receptor

Answer 11

M3 mAChR on parietal cells

Question 12

what blocks the the M3 mAChR receptor?

Answer 12

atropine

binding of ACh to M3 leads to IP3/Ca cascade that results in secretion of H/K ATPase activation

ACh indirectly activates ECL cells which release histamine

Question 13

Gastrin

what secretes it, what happens to it

Answer 13

released by G cells in the antrum into the blood, returned to stomach by circulation

binds to CCKb receptors and causes IP3/Ca cascade —> H/K ATPase activation

indirectly stimulates ECL cells to release histamine

Question 14

CCKb

Answer 14

affinity for gastrin and CCK

Question 15

CCKa

Answer 15

affinity for CCK only

Question 16

gastrin is stimulated by

Answer 16

stomach distention

presence of small peptides and amino acids, and vagus nerve

Question 17

Atropin blocks

Answer 17

vagal stimulation of M3 mAChR receptors, but does not block vagal stimulation of G cells secreting gastrin

Question 18

somatostatin

Answer 18

a paracrine

inhibits HCL

released from D cells, mostly located in antrum

binds to somatostatin receptors (receptor type 2, SSTR2) on parietal cell

binding of somatostatin to its receptor inhibits adenylate cyclase that results in inhibition of H (direct pathway)

indirect pathway: inhibits both histamine released from ECL cells and gastrin release from G cells

Question 19

what inhibitor is used to treat gastric ulcers?

Answer 19

omeprazole

blocks H-K ATPase

Question 20

what inhibitor is used to treat doudenal ulcers?

Answer 20

cimetidine, treats both duodenal, gastric ulcers, gastroesophageal reflux disorders by blocking H2 histamine receptors

Question 21

atropine blocks what and why, but does not block what and why

Answer 21

blocks the M3 mAChR on parietal cells; a DIRECT pw block

does not Gastrin cells because they use GRP receptors

Question 22

Gastric HCL secretion 3 phases

Answer 22

1. cephalic
2. gastric
3. intestinal phase

Question 23

Gastric ulcer

Answer 23

low H 
high gastrin levels because H is low 
forms primarily because of mucosal barrier is defective 
h pylori usually associated with this 
diagnostic instrument: urease enzyme

Question 24

Duodenal ulcer

Answer 24

high H
high gastrin levels in response food ingestion
h pylori infection less here, but can spread from stomach and inhibit somatostatin, causing increase

Question 25

Zollinger Ellison Syndrome

Answer 25

usually the result of a tumor in the head of the pancreas secreting gastrin

high H, high Gastrin

Question 26

Exocrine pancreas

Answer 26

makes up around 90% of the pancreas

glands are like salivary glands: acinus with centroacinar and ductal cells

acinus releases enzymes, centroacinar and ductal cells release HCO3

Question 27

Exocrine pancreas innervation: sympathetics AND parasympathetics

Answer 27

sym comes from celiac and superior mesenteric plexuses

parasym: comes from vagus n

vagal pregang synapse at ENS
postgang synapse on the exocrine pancreas

sym: decrease in activity
parasym: increase in activity

contrast to salivary glands where sym and parasym do the same thing

Question 28

High yield question

pancreas secretes which enzymes in their active and inactive form

Answer 28

secretes amylases and lipases in their active form, but proteases in their inactive form

Question 29

centeroacinar and ductal cells release

Answer 29

Na, K, Cl, HCO3

Question 30

when pancreatic flow rate is low, the two highest ions secreted include

Answer 30

chlorine and sodium

Question 31

when pancreatic flow rate is high, the two highest ions secreted include

Answer 31

HCO3 and Na

Question 32

HCO3/CL relationship in pancreatic seretions

Answer 32

reciprocal

Question 33

Cephalic phase of pancreas

Answer 33

same as for salivary glands but results mainly in enzymatic secretion

Question 34

gastric phase of pancreas

Answer 34

like salivary glands but mostly enzymatic secretion

Question 35

intestinal phase of pancreas

Answer 35

like salivary glands but enzymatic AND aqueous secretions