120-121b Secretion

Question 1

CN parasympathetic innervation for submandibular, sublingual, paotid glands?

Answer 1

VII - facial
VII
IX - glassopharyngeal

Question 2

salivary secretion function?

Answer 2

1) Protective - HCO3 neutralizes bacterial acid; Antibodies

2) Digestion - amylase for starch digestion (most from pancreas though); mucin lubricate food

Question 3

salivary secretion control?

Answer 3

• Autonomic

- due to stimuli in cephalic phase (smell, sight, etc)

Question 4

is the ANS antagonistic (sym vs parasym) for salivary secretion?

Answer 4

NO - synergistic with each other

Question 5

sympathetic innervation pathway to salivary glands?

Answer 5

spinal cord (t1-4) –>
superior cervical ganglion –>
blood vessels –>
glands

Question 6

sympathetic input to salivary glands uses what nt? does what?

Answer 6

NE

1) salivary secretion at low volume w/ high protein from innervation of glands

2) vasoconstriction from innervation of blood supply
* *different neurons do these 2 things**

Question 7

parasympathetic innervation to salivary uses what nt? does what?

Answer 7

ACh + cotransmitters

Not vagus - preganglionic in brain stem, post gang are in otic and submandibular ganglion

1) large volume of saliva that is watery
2) vasodilation due to increased metabolism of gland + release of VIP (vasoactive polypeptide)

Question 8

Salivary glands layout

Answer 8

acinar cells lead to striated duct cells

Question 9

function of myoepithelial cells? innervation?

Answer 9

contractile - squeeze fluid from acinus into duct

parasympathetic and sympathetic

Question 10

what determines composition of salivary?

Answer 10

secretory rate

low flow = hypotonic w/ K>Na (unusual)

high flow = more isotonic - approaches concentration of plasma for cations, bicarb stays constant; duct cell modification is overwhelmed

Question 11

what happens to saliva in acinus? straited ducts?

Answer 11

acinus = isotonic ions (including HCO3) + amylase and other proteins

striated ducts = modification of ionic content remove Na and Cl
add HCO3 and K

Question 12

pancreas/salivary acinar secretion - what drives process? what order do things happen? overall?

Answer 12

1) basolateral 3Na/2K ATPase drives process - increases K inside cell, decrease Na inside cell –> makes inside negative
2) Negative gradient drives Cl thru apical side into lumen -> makes lumen negative
3) negative lumen attracts Na to lumen between cells
overall - active transport of Na and Cl (indirectly)

Question 13

salivary and pancreatic Ductile cell secretion/modification - what drives? what is the process? Can water leave lumen? overall?

Answer 13

1) basolateral 3Na/2K ATPase sets up a gradient for Na to enter the cell in exchange for H+ ion which causes basic cell interior
2) Bicarb (basic) thus forced out of cell on apical side in exchange for Cl
3) Cl then leaks out on apical side via CFTR channel back into lumen

tight jxns between ductile cells prevent movement of water in/out of lumen –> drives osmolarity down and leads to hypotonic secretion

Overall: Na replaced with K in lumen in a 3/2 ratio

Question 14

saliva -tonicity, content?

Answer 14

hypotonic - low in Na, high in K, high in Bicarb

Question 15

why is saliva hypotonic?

Answer 15

tight junctions in ducts prevent water movement - intial acinus secretion is nearly isotonic but modified by ducts

Question 16

stomach - where are gastric acid secretions occurring? by what cell?

Answer 16

gastric glands

parietal cell

Question 17

gastric acid content at low flow? high flow? tonicity?

Answer 17

low = Na Cl - can actually be basic (surface cell)

high = H Cl - with lots of K and very low Na (parietal cell)

isotonic at all flow rates

Question 18

Parietal cell secretion process? overal?

Answer 18

1) hydrolysis of water - creates H+ (requires a lot of E)
2) H+ pumped into lumen by H/K ATPase (proton pump) which leaves OH- in cell so combines with CO2 via CA to make bicarb which leaves cell in exchange of Cl-

overall - equal and opposite - secretes acid into lumen and base into interstital/blood stream

Question 19

what signals control parietal secretion (intracellular signal)? where type of input are these? where do they come from?

Answer 19

1) ACh on M3 receptor (Ca)
neuronal
Vagas + intrinsic from ENS

2) Histamine on H2 receptor (cAMP)
paracrine
ECL cell

3) Gastrin on CCK3 receptors (Ca)
hormonal
G cells in antrum (also acts on ECL cell to increase histamine release)

**act synergistically due to convergance of intracellular pathways

Question 20

what makes pepsin? role? how is stored? how is activated?

Answer 20

chief cells (stomach)

protein digestion

pepsinogen to prevent eating self

acid cleaves part of protein to activate AND pepsin can cleave pepsinogen

Question 21

primary stimulus for gastric motility and secretion?

Answer 21

stomach distention (gastric phase) activates vagovagal and local ENS reflexes

Question 22

what intestinal hormones reduce gastric motility and secretion (cell type, location)?

Answer 22

Secretin (S cells, duodenum) and CCK (I cells, duodenum, jejunum)

Question 23

why does the stomach not digest itself?

Answer 23

gastric acid secretion low b/w meals
stomach cells have tight junctions
interstitial is high in bicarb
mucosal protective batter from bicarb from surface cell (insoluble mucus secretion)

Question 24

what do damaged cells release? what does this do?

Answer 24

histamine - activates parietal cells

Question 25

exocrine pancreas - cell types and what do they secrete?

Answer 25

acinus - proteins/enzymes via CCK(I cells in duod) and secretin (s cells in duodenum)

duct cell - HCO3 from secretin(S cells in duodenum)

Question 26

pancreatic sectretion and flow rate

Answer 26

varies with flow but cation constant at all flow rates

low = Na/Cl

high=Na/HCO3

HCO3 neutralizes acid coming into intestine to raise pH to make enzymes function

Question 27

pancreas secretion - overview

Answer 27

active Na and Cl secretion

Question 28

what drives pancreas secretion?

Answer 28

ACh and CCK

Question 29

pancreatic duct cell function? method? what controls

Answer 29

secrete HCO3

similar to duct cell in salivary gland - H+ driven out of cell via Na/K ATPase gradient AND direct H+ ATPase –> creates pH imbalance which drives bicarb out w/ water and Na following between cells (isotonic)

CCK and secretin control