The Endocrine Pancreas Flashcards Preview

Regulatory Physiology and Pharmacology > The Endocrine Pancreas > Flashcards

Flashcards in The Endocrine Pancreas Deck (29):
1

What is the pancreas?

a triangular gland with both exocrine and endocrine cells located behind the stomach

2

What do the acinar cells do?

produce enzyme rich juice for digestion

3

What do the pancreatic islets do?

produce hormones involved in regulating fuel storage and use

4

What are the cells contained within the islets and what do they produce?

b - cells - insulin
a- cells - glucagon
d - cells - somatostatin
F cells - pancreatic polypeptide

5

What is insulin?

protein hormone with 2 aa chains linked by disulphide bonds

6

How is insulin sythesised?

as proinsulin to produce 51AA insulin and Cpeptide 29aa

7

On what chromosome is the DNA for insulin?

11

8

What is the insulin synthesis pathway?

DNA -> mRNA -> preproinsulin (with signal peptide and c peptide) -> proinsulin -> insulin

9

Why is the signal sequence required?

to allow the hormone into the ER

10

What is insulin synthesis stimulated by?

glucose or feeding

11

What is the threshol of glucose-stimulated insulin secretion?

100mg/dl

12

How does glucose increase insulin secretion?

rapidly increases translation of mRNA and slowly increases transcription of DNA

13

What is the pathway for stimulating insulin release?

GLUT2 brings more glucose into the cell
glucose is made into ATP
ATP closes ATP sensitive K channel
Cell depolarises and opens VGCC
Ca stimulates vesicles to exocytose by using SNARE proteins

14

What are the stimulators of insulin secretion?

increase serum glucose, amino acids, FFA,ketone bodies

15

What are the inhibitors of insulin secretion?

decrease glucose, amino acids, FFAs, somatostatin and epinephrine

16

What are the inhibitors of insulin secretion?

decrease glucose, amino acids, FFAs, somatostatin and epinephrine

17

What is the low threshold for insulin production?

50mg/dl

18

When is insulin secretion half-maximal?

150mg/dl

19

When is insulin secretion at maximal response?

300mg/dl

20

Why is insulin secretion bi-phasic?

initial secretion of all insulin stores creates peak
then gradual increment as insulin is produced as long as blood glucose is high

21

What is glucagon?

29aa polypeptide that is a hyperglycaemic agent

22

What is the major target of glucagon?

glycogenolysis
gluconeogenesis
release of glucose to blood from liver cells

23

How is glucagon synthesised?

DNA -> mRNA -> preproglucagon-> proglucagon -> glucagon

24

What are stimulators of glucagon secretion?

decreased blood glucose, increased serum amino acids
stress
exercise
sympathetic nervous system

25

What are inhibitors of glucagon secretion?

somatostatin
insulin
increased blood glucose

26

What is somatostatin released in response to?

same things as insulin, increased blood glucose, amino acids, and fatty acids

27

what does somatostatin do?

decreases gut motility and secretion and inhibits gastrin , CCK and GIP

28

What is pancreatic polypeptide?

released in response to - ingestion of protein rich meal, low blood sugar, and strenuous exercise

29

What does the pancreatic poly peptide do?

inhibits gall bladder contraction and pancreatic exocrine secretion