Endocrine Pancreas

Question 1

pancreas location and describe its development

Answer 1

posterior to the stomach

largest gland ande develops embryologically as an outgrowth from the foregut

[fore gut = coelic trunk / midgut = Superior mesenteric artery / hindgut = inferior mesenteric artery]

Question 2

functions of pancreas

Answer 2

• exocrine ; acini 99% wc release digestive enzymes directly into duedenum (OCCUPY MOST OF THE SPACE)
• endocrine ; islets of langerhans 1% releases hormones (OCCUPY LITTLE OF THE PANCREAS)

Question 3

GI 3 devisions and where is pancreas

Answer 3

foregut; supplies by b from coeliac trunk

midgut; supplied by b from superior mesenteric artery

hindgut ; inferior mesenteric artery -

outgrowth of a foregut structure so supplied by coeliac trunk

Question 4

histology of islets of lagerhands

Answer 4

imge

Question 5

hormones made by islets of langerhans and the cell types

what type of hormones are released?

Answer 5

• somatosatin : D cells (delta)
• insulin : B cells (beta)
• gluagacon A cells (alpha)
• gastrin G cells
• ghrelin e cells
• vasoactive intestinal peptide
• pancreatic polypeptide PP

peptie hormones

Question 6

for insulin and glucagon whats the function

Answer 6

regulation of metabolism of carbs, fats and proteins

• insulin lowers - glucagon ^

Question 7

where are the actions of glucagon and insulin

Answer 7

• I; liver,adipose,skelteal,muscle
• G; liver, adipose

Question 8

normal bgl , after meal?renal threshold?

Answer 8

• 3.5-5mmol/L
• 7-8mmol/L
• 10mmol/L

Question 9

whats glycosuria and what are changes in it?

Answer 9

• g in pee
• pregnant ladies d v renal threshold
• elderly have ^ threshold

Question 10

insulin is a/c? what other key words is it?

Answer 10

• anabolic
• anti-gluconeogenic and anti-lipolytic and anti-ketogenic

Question 11

how is insulin made

Answer 11

• preproinsulin made by ribosomes on the RER
• the single peptide then directs it into the cisternal region of RER where it is cleaved off, undergoes modification and folds where correct alignment of cysteine residues
• goes into Golgi where packaged into storage vesicles wc undergo proteolysis whereby remove connecting peptide C peptide (wc consists of 31aa joined together with 4 basic aa(3 arginine and 1 lysine) , so the proinsulin breaks into C peptide and insulin
• vesicles marginated wc means vesicle contains insulin and C peptide and they sit under cell membrane in pancreatic beta cell and wait till they are released when the correct stimulus is present wc is the Katp channels shutting as a result of ^glucose
• the vesicle then fused with membrane and release contents via exocytosis

Question 12

how is insulin stored in the vesicle during margination

Answer 12

crystalline zinc-insulin complex

Question 13

what type of receptor family is insulin

Answer 13

tyrosine kinase

Question 14

how is insulin release

Answer 14

• ATP sensitive insulin channel on plasma membrane open allow efflux of k+ ion c membrane to become more
• d hyper-polarisation
• if metabolism is low, so v ATP so cant inhibit it so, they open and no insulin related
• if metabolism high, ^ ATP wc inhibits these channels c them to close and insulin released
• v gated ca2+ Channes are activated and allow movement of ca2+ to enter the cell down th eocnc gradient, and this ca2+ c exocytosis of the marginated insulin vesicles

Question 15

what does insulin do then to the glucose

Answer 15

stimulates it being taken up in liver fat skeletal via GLUT 4 channel

Question 16

what does glucagon do and how it is synthesised

Answer 16

synthesised in rER, same as insulin and marginate, lower plasma glucose level they are released via exo and act on target to ^ lv of - don’t need to know cell signalling of glucagon

Question 17

why is glucagon useful in clinical

Answer 17

-glucagon is event to hypoglycaemia

Question 18

what type of receptor does glucagon bind to on cell surface membrane and what happens

Answer 18

binds to Gcouple Protein receptor

causes the enxyem andeylate cyclase to activate wc increases cAMP intracellularly

high cAMP activates protein Kinase A wc phosphorylates and thereby activates a number of important enzymes in target cells

Question 19

type 1 diabetes

Answer 19

autoimmune destruction of pancreatic beta cells

Question 20

type 2 diabetes

Answer 20

resistance to insulin

defective post receptor events

or exvessive inapporitate glucagon

Question 21

what happens to an insulin resistant patient thats young (12 yrs old)

Answer 21

first B cells copensate by ^ insulin levels

B cells then fail to maintain ^ insulin lvels so impaited glucose tolerance

finally B cell dysfunction leads to relative insulin defieceny

pateint develops overt type 2 diabetes