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BCH3120 > Hormonal Regulation > Flashcards

Hormonal Regulation Flashcards

1
Q

Hypothalamus/pituitary gland function

A

Controls appetite and stress

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2
Q

Adipocytes function

A

Secrete adipokines (appetite and metabolic activity)

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3
Q

Adrenal glands function

A

Secrete catecholamines (epinephrine, norepinephrine)

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4
Q

Pancreas function

A

Secretion of glucagon (catabolic) and insulin (anabolic)

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5
Q

Glucagon is a [blank] homrone

A

catabolic

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6
Q

Glucagon is secreted by [blank] and function is to

A

Secreted by pancreatic alpha cells and restores blood glucose levels (receptor expressed mainly in liver, kidney and adipose tissue)

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7
Q

Hormonal signalling step 1 (catabolic = glucagon)

A

Hormone binds to a G-protein-coupled receptor
-G-proteins are guanine-nucleotide binding proteins
-Heterotrimeric complex (Gα, β and γ)
-Gα can bind GDP or GTP (active when bound to GTP)

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8
Q

Hormonal signalling step 2 (catabolic = glucagon)

A

Binding of the hormone to its receptor leads to a change in conformation of the receptor that allows the recruitment of the G-proteins complex.

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9
Q

Hormonal signalling step 3 (catabolic = glucagon)

A

This interaction allows the exchange of the GDP located on the Gα subunit for a new molecule of GTP.
The Gα -GTP complex detaches from the G-protein complex.

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10
Q

Hormonal signalling step 4 (catabolic = glucagon)

A

Adenylyl cyclase (also called adenylate cyclase) is activated by binding of the active Ga (loaded with a GTP).
-The enzymatic activity of adenylyl cyclase take places in the cytoplasm.
-Adenylyl cyclase catalyzed the conversion of ATP into cyclic AMP (cAMP)

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11
Q

Cyclic AMP (cAMP) function

A

is a second messenger important for many biological processes:
1) Regulation of glycogen, carbohydrates and lipids metabolism
2) cAMP is an activator of PKA (Protein kinase A)

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12
Q

Hormonal signalling step 5 (catabolic = glucagon)

A
  1. cAMP molecules bind to the regulatory subunits of PKA.
    -PKA is composed of two catalytic and two regulatory subunits.
    -In absence of cAMP, the regulatory units inhibit the activity of the catalytic subunits.
    -Binding of cAMP to the regulatory subunits of PKA causes a change in conformation in these subunits
    -The change in conformation release the catalytic subunits.
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13
Q

Hormonal signalling step 6 (catabolic = glucagon)

A

The free catalytic subunits of PKA are now activated and can phosphorylated key regulating enzyme implicated in various metabolic pathway.

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14
Q

How to restrict the effect of cAMP

A

To restrict the effect of cAMP, excess cAMP is converted to AMP by members of the phosphodiesterase (PDE) family.

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15
Q

Homronal signalling pathway 9 steps summarized

A
  1. Catabolic hormone receptors are coupled to G-proteins
  2. Binding of the hormone leads to activation of the receptor
  3. Receptor activation is mediated by the G-protein
  4. Upon activation, the Gα monomer dissociates
  5. Gα diffuses and activates adenylate cyclase (AC)
  6. Adenylate cyclase converts ATP to cAMP
  7. cAMP activates the cAMP-dependent protein kinase A (PKA)
  8. PKA phosphorylates target regulatory enzymes
  9. Phosphodiesterase (PDE) converts cAMP into AMP in order to attenuate the catabolic effect
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16
Q

Key regulatory enzyme of glycogen synthesis

A

Glycogen synthase

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17
Q

Key enzyme of glycogen breakdown

A

Glycogen phosphorylase

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18
Q

Glucagons role in glycogenolysis

A
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19
Q

Key regulatory enzyme of glycolysis

A

PFK and Pyruvate Kinase

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20
Q

Key regulatory enzyme of gluconeogenesis

A

FBPase-1

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21
Q

Role of F26BP in the liver and its impact on PFK-1 and FBPase-1 activity

A
22
Q

Glucagon role in gluconeogenesis

A
23
Q

Key regulatory enzyme of FAS

A

ACC (Acetyl-CoA carboxylase)

24
Q

Key regulator enzyme of cholesterol

A

HMG-CoA reductase

25
Q

Key regulatory enzyme of FA release from TAG

A

Perilipin and HSL

26
Q

Glucagon signalling on lipogenesis and ketogenesis

A
27
Q

Glucagon signalling on cholesterol biosynthesis

A
28
Q

Glucagon signalling on TAG homeostasis

A
29
Q

List of pathways glucagon regulates

A
30
Q

Insulin signalling (anabolic hormone) step 1

A

The binding of insulin to its receptor leads to a change in conformation resulting in the autophosphorylation of the receptor (tyrosine residues)

31
Q

Insulin signalling (anabolic hormone) step 2

A

Phosphorylated tyrosines are recognized by members of the Insulin Receptor Substrate family (mainly IRS1 and 2)

32
Q

Insulin signalling (anabolic hormone) step 3

A

This binding triggers the phosphorylation of tyrosine residues on IRS proteins

33
Q

Pip2 and Pip 3 are membrane lipids derived from

A

PI

34
Q

Insulin signalling (anabolic hormone) step 4

A

Phosphorylated IRS proteins are recognized by PI3-kinase (Phosphatidylinositol-4,5-bisphosphate 3-kinase)

35
Q

Insulin signalling (anabolic hormone) step 5

A

This binding leads to the activation of PI3K, which in turn phosphorylates PIP2 to make PIP3.

36
Q

Insulin signalling (anabolic hormone) step 6

A

Akt/PKB is recruited to the membrane by PIP3 where it will be phosphorylated by PDK1 (3-phosphoinositide-dependent protein kinase 1

37
Q

Phosphorylation of Akt/PKB by PDK1

A
38
Q

Insulin signalling (anabolic hormone) step 7

A

Once activated, Akt/PKB is released from the membrane. It will access the cytoplasm, where it will phosphorylate and inactivate GSK-3 (glycogen synthase kinase-3).

39
Q

Insulin signalling (anabolic hormone) step 8

A

Akt/PKB will also phosphorylate and activate PDE (phosphodiesterase), accelerating the conversion of cAMP into AMP.

40
Q

Insulin signallings effect on glycogen synthesis and break down

A
41
Q

Insulin signalling with glucose formation

A

**Note: Binding of insulin leads to the translocation of FLUT4 which occurs in the muscle

42
Q

Insulin signalling with glucose formation

A

**Note: Binding of insulin leads to the translocation of GLUT4 which occurs in the muscle

43
Q

Key regulatory enzyme for glucoose uptake

A

GLUT4

44
Q

Key enzyme for Fatty Acid storage

A

cAMP, LPL

45
Q

Insulin signalling in FA synthesis

A
46
Q

Insulin signalling in cholesterol synthesis

A
47
Q

Insulin signalling in TAG synthesis

A
48
Q

Summary of insulin and its metabolic effects

A
49
Q

Insulin pathway through all the systems we studied

A
50
Q

2 hormones that cause stress are

A

1) epinephrine
2) norepinephrine

51
Q

4 main effects of stress on metabolism and physiology

A

BCH3120 (36 decks)

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