Lecture 23 - Fed, Fasting, Starvation & Diabetes

Question 1

Fatty Acid importance and Tissue Location

Answer 1

Critical to cellular function
They provide the cell with a source of energy
Fatty acid synthesis occurs in cytosol of liver, adipose tissue and mammary glands

Question 2

Fed State

Answer 2

Food absorbed from intestine 
Food intake meeting energy requirements
Excess food leads to formation of storage forms of energy
- glycogen
- triacylglycerol

Question 3

Metabolite Flow during Fed State

Answer 3

Liver:
Blood glucose -> glycogen, pyruvate
FFA -> VLDL, TAG
Amino acids -> protein
Muscle:
Blood glucose -> glycogen, pyruvate, lactate
FFA -> TAG
Amino acids -> protein
Adipose:
Blood glucose -> pyruvate
FFA,VLDL -> lipid droplets

Question 4

Fasting State

Answer 4

Up to 2 days after food intake
During fasting body needs to maintain supply of glucose (2.5mM)
Hypoglycaemia occurs if falls below 2.5mM
- lack of coordination
- muscle weakness
- confusion

Question 5

Metabolite Flow during Fasted State

Answer 5

Liver:
Glycogen -> glycogenolysis -> glucose
Oxaloacetate -> gluconeogenesis -> glucose
Acyl CoA -> Acetyl CoA
Acetyl CoA -> ketone bodies
Muscle:
Glycogen -> glucose -> glycolysis -> pyruvate, lactate
Acyl CoA -> Acetyl CoA
Amino acids  protein
Adipose:
Glucose -> pyruvate
TAG -> FFA
Acyl CoA -> Acetyl CoA

Question 6

Ketone Bodies

Answer 6

Important source of fuel during starvation
Produced in liver mitochondria
Transported by blood to extrahepatic tissue such as skeletal and heart
Used as source of fuel as catabolism is function of extrahepatic tissue

Question 7

Ketone Bodies in Starvation and Diabetes

Answer 7

Formation increases in both starvation and diabetes
Increase ketone body concentration in blood lowers pH causing acidosis
Oxaloacetate shunted away from TCA cycle into gluconeogenesis reducing acetyl CoA entering TCA cycle
Excess acetyl CoA is used for Ketone body synthesis
Protein from muscle is catabolised and amino acids used for gluconeogenesis and ketogenesis

Question 8

Formation of Ketone Bodies

Answer 8

Occurs in liver

5 reactions in liver mitochondria

Question 9

Type 1 Diabetes

Answer 9

Insufficient insulin
Extrahepatic tissue cant take up glucose
Causes ketoacidosis