MCB Lecture 16 The Fasting State Flashcards

0
Q

Wat is resting blood glucose levels?

A

5 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What concentration of glucose in the blood constitutes fasting?

A

< 4.5 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does glucagon bring about?

A

Liver: gluconeogenesis, glycogenolysis
Muscle: glycolysis, glycogenolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which organs are prioritised in terms of glucose?

A

Brain
Retina
RBCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the ligand in the Glucagon signal transduction pathway in the liver?

A

Glucagon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the receptor in the glucagon signal transduction pathway in the liver?

A

Glucagon receptor (GPCR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the G-Protein in the glucagon signal transduction pathway in the liver?

A

Guanyl nucleotide G protein

GDP replaced with GTP, which activates Adenyl cyclase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the second messenger in the glucagon signal transduction pathway in the liver?
What happens from here?

A

Adenyl cyclase converts ATP to cAMP
cAMP activates PKA
PKA phosphorylates proteins, either switching them on or off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the PKA targets in the liver hepatocyte? (5)

A
  1. PFK-2/F-1,6-bP-2
  2. Glycogen synthase
  3. Pyruvate kinase
  4. PEP carboxykinase
  5. Glycogen phosphorylase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the overall signal-transduction pathway of glucagon in the liver

A
  1. Glucagon binds to
  2. Glucagon receptor
  3. G-Protein activates, which activates
  4. Adenyl cyclase which converts
  5. ATP -> cAMP
  6. PKA activates by cAMP
  7. Proteins activated by PKA (phosphorylation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the overall pathway of adrenaline signal-transduction in liver cells

A
  1. Adrenaline binds to
  2. Beta-adrenergenic receptor which activates
  3. G protein (same as glucagon)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do the adrenaline and glucagon pathways differ?

A

The adrenalin pathway has a different ligand and receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is adrenaline synthesised from?

A

Tyrosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

We’re is adrenaline released from?

When is it released?

A

It’s released from the adrenal cortex

It is released in response to stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

From where is glucagon released?

A

Alpha cells of the pancreas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the mechanism of activation of Glycogen Phosphorylase by PKA?

A
  1. PKA phosphorylates and activates Phosphorylase Kinase

2. Phosphorylase Kinase phosphorylates and activates Glycogen Phosphorylase

16
Q

What is the mechanism of activation of PEP carboxykinase by PKA?

Which pathway is this involved with?

A
  1. PKA phophorylates and activates CREB
  2. CREB enters the nucleus and activates transcription of PEP carboxykinase

This is part of the glucagon and the adrenaline pathways

17
Q

To which hormone are hepatocytes more responsive in the fasting state?

A

Glucagon more than adrenaline

18
Q

Compare the structure of glucagon and adrenaline

A

Glucagon is a peptide hormone

Adrenaline is a steroid hormone

19
Q

From where is glucagon released?

When is it released?

A

The alpha cells of the pancreas

It is secreted in the fasting state, ie when blood glucose concentration is low (less than 4.5 mM)

20
Q

Which organs have glucagon receptors?

A

The liver