Pancreas: Histo and Physio Flashcards

1
Q

definies head/neck of pancreas?

A

gastroduodenal a.

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2
Q

a. behind neck

A

SMA merges emerges at inferior border

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3
Q

tail of pancreas

A

TV12
invested in splenophrenic ligemanent
may be injured during splenectomy

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4
Q

Main duct “wirsung”

A

comes from ventral bud and distal dorsal bud, more inferior

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5
Q

accessory duct “Santorini”

A

comes from proximal dorsal bud - drains superior portion of head

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6
Q

exocrine pancreas

A
  1. acinar cells: secrete zymogens, amylase, lipase, trypsinogen (pancreatic enzymes)
  2. ductal cells: secrete H20 and bicarb
    Centroacinar cells: duct cells that secrete HCO3
  • final digestive juice is alkaline and isosmotic.
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7
Q

Endocrine pancreas

A
islets of langerhans
Alpha cells: glucagon
Betal cells: insulin 
delta cells: somatostatin
PP cells: pancreatic polypeptide: stimulates gastric chief cells, inhibits bile secretion and inhibits pancreatic enzymes and HCO3- secretion 

inhibited by sympathetics
stimulated by PS

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8
Q

secretin

A

acts locally and increases HCO3- secretion and pancreatic enzyme secretion

  • secretin is activated by high acidic content in the duodenum
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9
Q

motilin

A

increases gastric and intestinal motility

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10
Q

islet-acinar axis

A

means by which blood sugar regulates release of glucose

- comunication b/w all cells randomly arranged around vessels - all cells see blood

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11
Q

CCK

A
  • activated by fats/proteins in the duodenum
    stimulates the release of enzymes from acinar cells
  • Lipase is most important, because it is the only enzyme kthat can digest fat
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12
Q

pancreatic juice

A

secretion is opposite to that of the stomach, it is very alkaline
includes aqueous bicarb. and pancreatic enzymes

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13
Q

Aqueous Bicarb

A

secreted by duct cells of pancreas
stimulated by secretin
promotes NAHCO3- co transport
buffers pH for maximum enzyme activity, prevents damage to mucosa

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14
Q

Pancreatic enzymes

A

secreted by acinar cells
for digestion of meal and absorption of nutrients
includes: amylase, trypsinogen and most impiortantly lipase
stimulated by CCK

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15
Q

Amylase

A

acinar cell secretion
requires CL- to activate
break down of starch and glycogen

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16
Q

Trypsinogen

A

acinar cell secretion
activated by enteropeptidase
breaks down protein polypeptides

17
Q

Lipase

A

MOST IMPORTANT ENZYME OF PANCREAS!
cant digest fats without it
product of acinar cells
breaks down triglycerides

18
Q

enterokinase

A

needed to convert trypsiongen to trypsin

found in brush border of duodenal enterocytes

19
Q

how is pancreatic secretion regulated?

A

secretin, increases HCO3- (based on pH levels)

CCK increases enzyme secretion (based on fat/protein levels in duodenum)

20
Q

what factors cause CCK release?

A

CCK stored in I cells

  • when GA’s and AA’s are in stomach, CCK-RP and MP are released : these are required to activate CCK
  • CCK digests proteins and CCK-RP and MP, thus when no proteins/fats are in duodenum, CCK digests its own activator.
  • no trypsinogen is released
21
Q

factors causing secretin release?

A
  • released from S cells in duodenal mucosa
  • S cells are pH meters
    when pH drops, S cells secrete secretin, which stimulates ductal cells to increase bicarb. secretion
22
Q

duodenal ulcer

A

not enough secretin being released

or could be due to no acid in stomach, which also results in no secretin release

23
Q

steatorrhea

A

fat in stool
early sign of pancreatic dysfunction
reduced lipase and bicarb. secretion

24
Q

acute pancreatitis

A

obstructive: gallstones/ malignancy

retention of secretion in pancreas, digestion of pancreatic tissue

25
Q

chronic pancreatitis

A

mutated trypsin - not responsive to trypsin inhibitor
resutls in inflammation of pancreatic tissue
- could also be due to alcohol abuse

26
Q

Pancreatic polypeptide

A

stimulates gastric chief cells

inhibits bile secretion and inhibits pancreatic enzymes and HCO3- secretion

27
Q

vasoactive intestinal peptide (VIP)

A

similar to action of glucagon
secreted by delta-1 cells
increases pancreatic exocrine secretion

28
Q

Motilin

A

increases gastric and intesinal motility

secreted by EC beta cells along with secretin