Fed & Fasted State

Question 1

How is Hexokinase self regulated?

Answer 1

• As more glucose broken down , self-inhibited by product

- Body want’s to conserve + protect glucose stores

Question 2

Where is Glucokinase and how does it work?

Answer 2

• Pancreas + Liver
• Not self inhibited (as we want to decrease BG ASAPp)
• When blood glucose increases GLUT 2 and Glucokinase switch on = G-6-P = molecular switch that triggers insulin release

Question 3

What happens to glycogen enzymes in the fasted state?

Answer 3

• Switches on phosphorylase - glycogen broken down

- Switches off synthase - stop making it

Question 4

What happens to glycogen enzymes in the fed state?

Answer 4

• Switches off phosphorylase

- Switches on synthase

Question 5

What happens in the liver when blood glucose is low?

Answer 5

• Glucagon released via GPCR > GTP >Adenyl cyclase > PKA
• PKA phosphorylates protein = turns off kinase, turns on phosphatase
• Phosphatase dephosphorylates Fru-2,6 BP > Fru 6P = speeds up glycolysis + slows down gluconeogenesis
• So more glucose produced + released

Question 6

What happens in the liver when blood glucose is high?

Answer 6

• PKA switched off
• Insulin dephosphorylates protein = turns on kinase, turns off phosphatase
• Remakes Fru 2,6, BP = reduced gluconeogenesis, increases glycolysis

Question 7

How is insulin linked to Krebs cycle?

Answer 7

Insulin takes Acetyl CoA from krebs and produces malonyl = ket reg point in FA synthesis

Question 8

What are he key effects of insulin in Liver?

Answer 8

1. Upregulates glycogen production
2. Upregulates glycolysis to produce more Acetyl CoA
3. Upregulates FA synthesis to make fat from Acetyl CoA

Question 9

What is the role of lipoprotein lipase?

Answer 9

• Munches away at VLDL, takes out fat so it can be absorbed into tissues
• VLDL becomes smaller, turns into LDL, recycled back to Liver

Question 10

What happens to glucose in muscles?

Answer 10

• Muscles can’t export glucose, only store it for own needs

- GLUT 4 keeps tissues supplied with adequate = insulin responsive

Question 11

How is glycolysis regulated in almost every tissue in body and why is this different in the Liver?

Answer 11

• Adenylate control
• Wan’t Liver to break down as much glucose as possible to take it out of blood
• Therefore Liver needs overiding mechanism to keep glycolysis on = substrate cycle

Question 12

What is the role of brown fat?

Answer 12

Thermogenesis

Question 13

What happens to excess protein in the body?

Answer 13

• Goes into muscle to replenish protein used
• Excess AA’s go into Liver to be deaminated
• Carbon skeletons go into citric acid cycle to make ATP