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BIOL 432 Final > Pancreas and Diabetes > Flashcards

Pancreas and Diabetes Flashcards

1
Q

What are the three domains of an insulin receptor?

A
  • insulin binding domain
  • transmembrane domain
  • tyrosine kinase domain
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2
Q

What is the function of the insulin binding domain?

A
  • extracellular, binds insulin

- regulates kinase domain (keeps inactive until insulin binds)

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3
Q

What is the function of the transmembrane domain?

A
  • holds receptor in place and transmits conformation signal when insulin is bound (alpha helix change)
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4
Q

What is the function of the tyrosine kinase domain?

A
  • intracellular
  • autophosphorylates across to neighbour kinase domain plus recruits and phosphorylates substrates like insulin receptor substrate to start phosphorylation cascade
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5
Q

How does the kinase stay inactive until insulin is bound?

A
  • alpha subunit structurally constrains beta subunit
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6
Q

What is leprachaunism?

A
  • defecive IR
  • some mutations lead to less severe phenotype: insulin resistance
  • heterozygous less severe
  • elf-like features
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7
Q

Why would a heterozygous condition result in less severe leprechaunism?

A
  • recessive disorder

- both alleles must carry mutation

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8
Q

What are the differences in symptoms of type I and type II diabetes?

A
  • type I: weight loss, serious/never asymptomatic

- type II: obesity, asymptomatic

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9
Q

What causes type I diabetes?

A
  • no insulin producing B cells
  • most commonly caused by autoimmune disease that specfically destroys B cells in the pancreas
  • genetics may contribute
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10
Q

How is type I diabetes treated? What results if not treated?

A
  • with insulin, diet and lifestyle
  • hyperglycemia and eventually coma
  • no cure
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11
Q

What is type I diabetes?

A
  • juvenile diabetes or insulin-dependent diabetes

- chronic condition where pancreas produces little or no insulin

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12
Q

When does type I diabetes usually appear?

A
  • during childhood or adolescence

- sometimes adults

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13
Q

What are the three pre-requisites for development of type I diabetes?

A
  • B cell-reactive T cells need to be activated
  • response needs to be proinflammatory
  • immune regulation of autoreactive responses must fail
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14
Q

What is type II diabetes?

A
  • insulin present but target cell is resistant

- reduced insulin synthesis and insulin signaling

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15
Q

What are the 5 reasons a target cell is resistant in type II diabetes?

A
  • receptor insensitive or downregulated by hyperinsulinism
  • receptor defective
  • Ab against receptor blocks insulin
  • signal pathway defective
  • poor response of target organ due to obesity, liver disease, muscle inactivity
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16
Q

How is type II diabetes treated?

A
  • drugs that lower glucose production in liver and improve sensitivity to insulin
  • drugs that stimulate insulin secretion (may cause hypoglycemia)
  • drugs that affect the glucose absorption in the intestine
  • diet and exercise mainly
  • reduce stress, increase quality of sleep
17
Q

What does an islet cell look like in someone with type II diabetes?

A
  • B cells decrease
  • replaced by amyloid deposits
  • reduction in ratio of B cells to alpha cells (produce glucagon)
18
Q

How do drugs that affect the glucose absorption in the intestine work?

A
  • use incretin GLP-I o increase insulin and decrease glucagon
  • slow gastric emptying that can be helpful in controlling glucose levels
  • homologous to GLP-I but lasts longer and acts as GLP-I agonist
19
Q

What is lipogenesis?

A
  • store fat

- happens when we eat sugar

20
Q

What kind of diet impairs sugar tolerance? How does this relate to insulin resistance?

A
  • low carb and high fat diet

- we can decrease insulin resistance by decreasing fat intake

21
Q

What is hypoglycemia and what causes it?

A
  • occurs in diabetics when a treatment to lower the elevated blood glucose inaccurately matches the body’s physiological need
  • causes glucose to fall to a below-normal level
  • causes organ and brain damage without treatment
22
Q

What are glucose transporters regulated by?

A
  • glucose
23
Q

What are the three conditions relating to glucose regulation and how does this affect GLUT1?

A
  • hyperglycemic: too much glucose, downreg of GLUT 1
  • normal: appropriate amount of glucose, transported across BBB and delivered to neurons
  • hypoglycemic: upregulation of GLUT1 with too little glucose
24
Q

What is hypoglycemic unawareness?

A
  • when become desensitized to hypoglycemia so defenses are down
  • insulin, glucagon, epinephrine response attenuated
  • brain still gets enough sugar but can’t tell there is a problem
25
Q

____ ____ steps may be altered in type II diabetes.

A

insulin signaling

26
Q

What results from food intake?

A
  • increase insulin
  • release GLP-I and GIP from gut
  • further increase insulin
  • leads to glucose storage
27
Q

What results from exercise?

A
  • increase glucagon
  • need energy so breakdown storage products like carbs
  • increase blood glucose
28
Q

What results from a high amino acid meal in the presence of glucose?

A
  • increase insulin and glucagon

- protect from hypoglycemia (prevent insulin from lowering blood glucose too low)

29
Q

What results from starvation?

A
  • decrease insulin and decrease glucagon

- system needs to slow down and preserve energy

30
Q

What steps occur in the body to remove the glucose from our blood after a meal?

A
  • insulin inhibits glucagon
  • GLP-I releases at same time as insulin and increases insulin production
  • GLP-I slows gut emptying and increases absorption (inhibits food intake)
  • many other factors and complex interactions
31
Q

How is insulin removed from circulation?

A
  • degraded by insulinases within a few minutes

- receptors internalize

BIOL 432 Final (14 decks)

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