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regulatory physiology and pharmacology > the pancreas > Flashcards

the pancreas Flashcards

1
Q

What is proinsulin?

A

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

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2
Q

How is insulin derived from proinsulin?

A

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

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3
Q

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

A

proinsulin is inactive
insulin is active

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4
Q

Where does the conversion of proinsulin to insulin occur?

A

in the Golgi of pancreatic B cells

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5
Q

What is the primary stimulus for insulin secretion?

A

increased blood glucose

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6
Q

what is the islet of langerhan

A

bundle of endocrine cells in the pancreas

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7
Q

pancreatic alpha cells secrete ?

A

glucagon

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8
Q

pancreatic delta cells secrete

A

somatostatin

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9
Q

pancreatic F cells secrete

A

pancreatic polypeptide

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10
Q

functional cells are present at ___ months at gestation in utero

A

6

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11
Q

The final cleavage of insulin produces ___________ amounts of C peptide

A

equimolar

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12
Q

Fasting blood glucose =

A

4-5mmol l-1

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13
Q

postpandrial blood glucose=

A

up to 10mmol l-1

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14
Q

name stimulants insulin release

A

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

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15
Q

name inhibitor of insulin release

A

somatostatin
epi and norepi

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16
Q

what is more substantial ingested glucose or injected?

A

ingested

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17
Q

How do fatty acids influence insulin secretion?

A

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

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18
Q

Where does insulin synthesis begin in the cell?

A

in ribosomes of rough ER of pancreatic B cells

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19
Q

What is the initial form of insulin called?

A

preproinsulin

20
Q

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

A

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

21
Q

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

A

cell becomes depolarised and Ca channels open

22
Q

How does calcium affect insulin release?

A

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

23
Q

glucose is converted to ______ by glucose kinase

A

glucose-6-phosphate

24
Q

why is glucose-6-phosphate inportant in insulin secretion

A

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

25
Q

What is the precursor molecule to glucagon?

A

preproglucagon

26
Q

How is preproglucagon processed to form glucagon?

A

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

27
Q

What is the primary stimulus for glucagon secretion?

A

hypoglycaemia

28
Q

Name an amino acid that stimulates glucagon secretion.

A

alanine and arginine

29
Q

How does exercise affect glucagon secretion?

A

stimulates glucagon secretion

30
Q

name stimulates of glucagon secretion

A

GIP
epi
hypoglycaemia

31
Q

name inhibitors of glucagon

A

GLP-1
hyperglycaemia
somatostatin
insulin and amylin

32
Q

What is the primary role of insulin in glucose homeostasis?

A

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

33
Q

How does glucagon affect blood glucose levels?

A

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

34
Q

When is insulin secreted to regulate glucose?

A

after meals when blood glucose is high

35
Q

When is glucagon secreted to regulate glucose?

A

during fasting or when blood glucose levels are high

36
Q

What is the effect of insulin on glycogen synthesis?

A

promotes glycogen synthesis in muscles and liver to store excess glucose

37
Q

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

A

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

38
Q

What happens to insulin and glucagon secretion during hypoglycemia?

A

insulin secretion decreases
glucagon secretion increases

39
Q

What happens to insulin and glucagon secretion during hyperglycemia?

A

insulin secretion increases
glucagon secretion decreases

40
Q

What is Type 1 Diabetes Mellitus?

A

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

41
Q

What causes Type 2 Diabetes Mellitus?

A

insulin resistance due to pancreatic B cell dysfunction

42
Q

What are insulinomas?

A

rare pancreatic tumours that produce excessive insulin

43
Q

What is pancreatitis and how does it affect endocrine function?

A

inflammation of pancreas

44
Q

What is gestational diabetes?

A

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

45
Q

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

A

insulin pumps and continuous blood glucose monitors

46
Q

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

A

manual insulin dosing

regulatory physiology and pharmacology (17 decks)

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