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Cellular Processes > Hormones and Blood Glucose > Flashcards

Hormones and Blood Glucose Flashcards

1
Q

What hormones are involved in glucose homeostasis?

A
  • Insulin
  • Glucagon
  • Adrenaline
  • Glucocorticoids
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2
Q

When is adrenaline secreted in response to blood glucose?

A

When blood glucose is low

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3
Q

What is the effect of adrenaline on blood glucose?

A

It increases it by stimulating fuel metabolism in muscle and adipose tissue

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4
Q

What type of cells is glucagon secreted by?

A

α pancreatic cells

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5
Q

When are glucocorticoids secreted?

A

In reponse to stress and starvation

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6
Q

What type of receptor does glucagon bind to?

A

G-protein coupled receptor

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7
Q

What is PKA activated by?

A

cAMP

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8
Q

Outline how glucagon exerts its effects within a cell

A
  • Binds and causes a change in shape so GPCR can interact with G protein
  • Activated Gsα moves to adenyl cyclase and activates it
  • Adenyl cyclase catalyses cAMP formation which activates PKA
  • PKA phosphorylates cellular proteins
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9
Q

What reverses the activation of PKA?

A

Degradation of cAMP

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10
Q

How does cAMP activate PKA?

A
  • Regulatory subunits act in an inhibitory fashion
  • cAMP binds to regulatory subunits causing the catalytic subunits to be released
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11
Q

How can PKA alter gene expression?

A
  • PKA can activate CREB which is a transcription factor
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12
Q

How is the GPCR signal turned off?

A
  • Phosphodiesterase hydrolyses cAMP to AMP
  • intrinsic GTPase activity of α subunit
  • Receptor is phosphorylated and inactivated
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13
Q

How can a GPCR be inactivated?

A
  • Activated GPCR stimulates GPCR kinase to phosphorylate the GPCR at multiple sites
  • Arrestin binds to the phosphorylated sites
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14
Q

How does cholera toxin lock GPCRs in the active form?

A

It blocks the GTPase activity of the αs subunit

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15
Q

What are the cellular consequences of the cholera toxin?

A
  • continual activation of adenyl cyclase leads to high PKA activity
  • Activation of PKA means activation of CFTR Cl- channel and Na+/H+ opening them both
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16
Q

How does the cholera toxin cause diarrhoe?

A
  • opening of CTRF Cl- and Na+/H+ channels causes abnormally high [ions] into the surrounding of the gut
  • Water moves with the ions so water is lost from cells
17
Q

What channel does the cholera toxin affect?

A

CFTR Cl- channel

18
Q

What is the relationship of caffeine to adenosine receptors?

A

It acts as an antagonist

19
Q

What is the effect of caffeine on PKA activity in cells?

A

It increases it

20
Q

What enzyme does caffeine inhibit?

A

Phosphodiesterase

21
Q

What processes does glucagon activate?

A
  • glycogen breakdown
  • triglyceride breakdown
  • gluconeogenesis
22
Q

What processes does glucagon inhibit?

A
  • fatty acid synthesis
  • glycogen synthesis
  • glycolysis
23
Q

How does glucagon activate glycogen breakdown?

A
24
Q

How does glucagon activate triglyceride breakdown?

A

Activates and phosphorylates of hormone sensitive lipase

25
Q

How does glucagon activate gluconeogenesis?

A

Inactivates and phosphorylates PFK2

26
Q

How does glucagon inhibit fatty acid synthesis?

A

Phosphorylates and inactivates acetyl-CoA carboxylase

27
Q

How does glucagon inhibit glycogen synthesis?

A

Phosphorylation and inactivation of glycogen synthase

28
Q

How does glucagon inhibit glycolysis?

A

Phophorylates and inactivates pyruvate kinase

29
Q

What kind of receptor are adrenergic receptors?

A

GPCRs linked to hetertrimeric G proteins

30
Q

What is the effect of adrenaline on adipose?

A

Activates tricglyceride mobilisation

31
Q

What are the effects of adrenaline in muscle?

A
  • Activates glycogen breakdown
  • Inhibits glycogen synthesis
32
Q

What is the effect of adrenaline in the liver?

A

Activates glycogen breakdown

33
Q

How does adrenaline activate glycogen breakdown in the liver?

A

Ca2+ activates phosphorylase kinase

34
Q

Give examples of signalling molecules which can act as transcription regulators

A
  • Cortisol
  • Testosterone
  • Vitamin D3
35
Q

Outline how a signalling molecule can alter gene expression

A
  • Binds to its specific receptor on the nucleus
  • This causes confomational change of the receptor which binds to specific regulatory regions called hormone response elements in DNA
  • Receptor attracts coactivator or corepressor proteins and regulates transcription of the adjacent genes
36
Q

What are glucocorticoids?

A

Steroid hormones derived from cholesterol that are involved in the long term regulation of fuel metabolism and the immune system

37
Q

How many domains does the glucocortcoid receptor have?

A

3

38
Q

What are the 3 domains on the glucocorticoid receptor?

A
  • Transactivation domain
  • DNA binding domain
  • Hormone binding domain
39
Q

What are the effects of glucocorticoids?

A
  • Activate triglyceride mobilisation
  • Activates gluconeogenesis
  • Enhances protein catabolism
  • Has anti-inflammatory effects

Cellular Processes (22 decks)

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