MCB Lecture 16 The Fasting State Flashcards
Wat is resting blood glucose levels?
5 mM
What concentration of glucose in the blood constitutes fasting?
< 4.5 mM
What does glucagon bring about?
Liver: gluconeogenesis, glycogenolysis
Muscle: glycolysis, glycogenolysis
Which organs are prioritised in terms of glucose?
Brain
Retina
RBCs
What is the ligand in the Glucagon signal transduction pathway in the liver?
Glucagon
What is the receptor in the glucagon signal transduction pathway in the liver?
Glucagon receptor (GPCR)
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
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
What are the PKA targets in the liver hepatocyte? (5)
- PFK-2/F-1,6-bP-2
- Glycogen synthase
- Pyruvate kinase
- PEP carboxykinase
- Glycogen phosphorylase
Describe the overall signal-transduction pathway of glucagon in the liver
- Glucagon binds to
- Glucagon receptor
- G-Protein activates, which activates
- Adenyl cyclase which converts
- ATP -> cAMP
- PKA activates by cAMP
- Proteins activated by PKA (phosphorylation)
Describe the overall pathway of adrenaline signal-transduction in liver cells
- Adrenaline binds to
- Beta-adrenergenic receptor which activates
- G protein (same as glucagon)
How do the adrenaline and glucagon pathways differ?
The adrenalin pathway has a different ligand and receptor
What is adrenaline synthesised from?
Tyrosine
We’re is adrenaline released from?
When is it released?
It’s released from the adrenal cortex
It is released in response to stress
From where is glucagon released?
Alpha cells of the pancreas