the pancreas

Question 1

What is proinsulin?

Answer 1

precursor of insulin synthesised in pancreas that’s cleaved into insulin

Question 2

How is insulin derived from proinsulin?

Answer 2

c-peptides are cleaved to leave an A and B chain joined by disulphide bridges

Question 3

How do insulin and proinsulin relate in terms of biological activity?

Answer 3

proinsulin is inactive
insulin is active

Question 4

Where does the conversion of proinsulin to insulin occur?

Answer 4

in the Golgi of pancreatic B cells

Question 5

What is the primary stimulus for insulin secretion?

Answer 5

increased blood glucose

Question 6

what is the islet of langerhan

Answer 6

bundle of endocrine cells in the pancreas

Question 7

pancreatic alpha cells secrete ?

Answer 7

glucagon

Question 8

pancreatic delta cells secrete

Answer 8

somatostatin

Question 9

pancreatic F cells secrete

Answer 9

pancreatic polypeptide

Question 10

functional cells are present at ___ months at gestation in utero

Answer 10

6

Question 11

The final cleavage of insulin produces ___________ amounts of C peptide

Answer 11

equimolar

Question 12

Fasting blood glucose =

Answer 12

4-5mmol l-1

Question 13

postpandrial blood glucose=

Answer 13

up to 10mmol l-1

Question 14

name stimulants insulin release

Answer 14

blood glucose concentration
incretins (GLP-1, GIP)
glucagon
hyperkalaemia
vagal nerve stimulation

Question 15

name inhibitor of insulin release

Answer 15

somatostatin
epi and norepi

Question 16

what is more substantial ingested glucose or injected?

Answer 16

ingested

Question 17

How do fatty acids influence insulin secretion?

Answer 17

elevated free fatty acids stimulate insulin secretion but can cause insulin resistance

Question 18

Where does insulin synthesis begin in the cell?

Answer 18

in ribosomes of rough ER of pancreatic B cells

Question 19

What is the initial form of insulin called?

Answer 19

preproinsulin

Question 20

How does glucose entry into β-cells lead to insulin secretion?

Answer 20

glucose enters pancreatic B cells via GLUT2 leading to increase in intracellular ATP this closes ATP sensitive K channels

Question 21

What happens when ATP-sensitive K⁺ channels close in β-cells?

Answer 21

cell becomes depolarised and Ca channels open

Question 22

How does calcium affect insulin release?

Answer 22

Ca influx causes insulin vesicles to fuse with cell membrane and therefore insulin secretion

Question 23

glucose is converted to ______ by glucose kinase

Answer 23

glucose-6-phosphate

Question 24

why is glucose-6-phosphate inportant in insulin secretion

Answer 24

it undergoes TCA cycle to increase intracellular ATP needed to drive Ca influx

Question 25

What is the precursor molecule to glucagon?

Answer 25

preproglucagon

Question 26

How is preproglucagon processed to form glucagon?

Answer 26

cleaved in rough ER to form proglucagon then further processed to active glucagon

Question 27

What is the primary stimulus for glucagon secretion?

Answer 27

hypoglycaemia

Question 28

Name an amino acid that stimulates glucagon secretion.

Answer 28

alanine and arginine

Question 29

How does exercise affect glucagon secretion?

Answer 29

stimulates glucagon secretion

Question 30

name stimulates of glucagon secretion

Answer 30

GIP epi hypoglycaemia

Question 31

name inhibitors of glucagon

Answer 31

GLP-1 hyperglycaemia somatostatin insulin and amylin

Question 32

What is the primary role of insulin in glucose homeostasis?

Answer 32

lowers blood glucose by promoting glucose uptake in cells and storing glucose as glycogen

Question 33

How does glucagon affect blood glucose levels?

Answer 33

raises blood glucose levels by stimulating processes like glycolysis and gluconeogenesis in liver

Question 34

When is insulin secreted to regulate glucose?

Answer 34

after meals when blood glucose is high

Question 35

When is glucagon secreted to regulate glucose?

Answer 35

during fasting or when blood glucose levels are high

Question 36

What is the effect of insulin on glycogen synthesis?

Answer 36

promotes glycogen synthesis in muscles and liver to store excess glucose

Question 37

How do insulin and glucagon work together to maintain glucose balance?

Answer 37

insulin decreases blood glucose when levels are high and glucagon increases blood glucose when levels are low

Question 38

What happens to insulin and glucagon secretion during hypoglycemia?

Answer 38

insulin secretion decreases glucagon secretion increases

Question 39

What happens to insulin and glucagon secretion during hyperglycemia?

Answer 39

insulin secretion increases glucagon secretion decreases

Question 40

What is Type 1 Diabetes Mellitus?

Answer 40

autoimmune disease where body attacks pancreatic B cells leading to insulin deficiency

Question 41

What causes Type 2 Diabetes Mellitus?

Answer 41

insulin resistance due to pancreatic B cell dysfunction

Question 42

What are insulinomas?

Answer 42

rare pancreatic tumours that produce excessive insulin

Question 43

What is pancreatitis and how does it affect endocrine function?

Answer 43

inflammation of pancreas

Question 44

What is gestational diabetes?

Answer 44

diabetes that occurs usually in the 2nd or 3rd trimester of pregnancy

Question 45

What is a closed-loop system in Type 1 Diabetes management?

Answer 45

insulin pumps and continuous blood glucose monitors

Question 46

How does a closed-loop system differ from traditional insulin therapy?

Answer 46

manual insulin dosing