MCB Lecture 16 The Fasting State Flashcards Preview

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Flashcards in MCB Lecture 16 The Fasting State Deck (21)
0

What concentration of glucose in the blood constitutes fasting?

< 4.5 mM

1

Wat is resting blood glucose levels?

5 mM

2

What does glucagon bring about?

Liver: gluconeogenesis, glycogenolysis
Muscle: glycolysis, glycogenolysis

3

Which organs are prioritised in terms of glucose?

Brain
Retina
RBCs

4

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

Glucagon

5

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

Glucagon receptor (GPCR)

6

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

Guanyl nucleotide G protein

GDP replaced with GTP, which activates Adenyl cyclase

7

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

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

8

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

1. PFK-2/F-1,6-bP-2
2. Glycogen synthase
3. Pyruvate kinase
4. PEP carboxykinase
5. Glycogen phosphorylase

9

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

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)

10

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

1. Adrenaline binds to
2. Beta-adrenergenic receptor which activates
3. G protein (same as glucagon)

11

How do the adrenaline and glucagon pathways differ?

The adrenalin pathway has a different ligand and receptor

12

What is adrenaline synthesised from?

Tyrosine

13

We're is adrenaline released from?
When is it released?

It's released from the adrenal cortex

It is released in response to stress

14

From where is glucagon released?

Alpha cells of the pancreas

15

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

1. PKA phosphorylates and activates Phosphorylase Kinase
2. Phosphorylase Kinase phosphorylates and activates Glycogen Phosphorylase

16

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

Which pathway is this involved with?

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

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

Glucagon more than adrenaline

18

Compare the structure of glucagon and adrenaline

Glucagon is a peptide hormone
Adrenaline is a steroid hormone

19

From where is glucagon released?
When is it released?

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

Which organs have glucagon receptors?

The liver

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