Metabolic Homeostasis Flashcards
Why is metabolic homeostasis important?
- It allows organisms to cope with episodic food intake and varying energy demands
- Ensures fuel is stored during plenty and mobilised when required
What concentration of blood glucose consitutes hypoglycaemia?
2mM
What concentration of blood glucose consitutes hyperglycaemia?
Blood glucose concentration of >10mM
Which organs are obligate glucose utilising?
Brain/CNS and red blood cells
Why is hyperglycaemia a problem?
Because glucose is chemically and osmotically active
What are the symptoms of hypoglycaemia?
- Lethargy
- confusion
- lack of coordination
- Coma and death
What are the symptoms of hyperglycaemia?
- Excessive thirst (polydipsia)
- Excessive urination (polyuria)
Why is it a problem that glucose is chemically active?
Glucose attaches to proteins and lipids, altering function
What are the only two tissues that produce glucose for homeostasis?
The liver and kidneys
In the fed state what is the main use of acetyl-CoA?
To produce triacylglycerol
In muscle what is glycogen broken down to?
Glucose-6-phosphate
Can muscle contribute to net glucose levels?
No
What hormones are important in the starved state?
Adrenaline and Glucagon
What two processes dominate in the starved state?
- Gluconeogenesis
- Lipolysis
What is a glucogenic amino acid?
An amino acid whose carbon skeleton can be used to synthesise glucose via gluconeogenesis
What is acetyl-CoA used for in the starved state?
To make ketone bodies
Does red or white muscle have a large number of mitochondria?
Red
How does slow twitch muscle produce ATP?
Relatively slowly via oxidative phosphorylation
How does fast twitch muscle produce ATP?
Through anaerobic glycolysis
Which enzyme is involved in the generation of ATP from phosphocreatine?
Creatine kinase
Which enzyme senses the energy status of the cell?
AMP-activated protein kinase (AMPK)
Is the normal concentration of AMPK in a cell low or high?
Low
What activates AMPK?
ATP levels dropping and a proportionally greater increase in AMP
What type of processes are inhibited by AMPK?
Anabolic
