Metabolism 9

Question 1

What happens if the brain has too much or too little glucose?

Answer 1

• Hypoglycaemia causes faintness and coma

- Hyperglycaemia causes irreversible damage

Question 2

What ar the general metabolic features of the brain and nervous tissue?

Answer 2

Continuously high metabolic rate. Cant use fatty acids - uses ketone bodies partially and glucose.

Question 3

Give the general metabolic features of the heart?

Answer 3

Can oxidise fatty acids, ketone bodies and carbohydrates. It is completed aerobic.

Question 4

What are the metabolic features of skeletal muscle?

Answer 4

• During light contraction, ATP consumption is met by oxidative phosphorylation
• During vigorous contraction, muscle stores must break down glycogen, and lactate may be generated by anaerobic respiration.

Question 5

What are the metabolic features of the liver?

Answer 5

• The liver is the immediate recipient of nutrients absorbed by the intestines.
• Highly metabolically active
• Has a role in mainting blood glucose, storing glycogen
• Role in lipid metabolism

Question 6

What can the body do to avoid hypoglycaemia?

Answer 6

• Breakdown liver glycogen stores (glycogenolysis)
• Release fatty ackds from adipose tissue (lipolysis)
• Acetyl coA os converted to ketone bodies
• Gluconeogenesis occurs

Question 7

Outline the process of gluconeogenesis.

Answer 7

• It occurs in the liver.
• It is not a complete reversal of glycolysis, as some enzymes cannot be used.
• Oxaloacetate is also present in glycolysis.

Question 8

What are the bypass enzymes in gluconeogenesis?

Answer 8

• Glucose 6-phosphate instead of hexokinase
• Fructose 1,6 bisohosphatase instead of phosphofructokinase
• Phosphoenolpyruvate carboxykinase and pyruvate carboxylase instead of pyruvate kinase

Question 9

What is the role of adrenalin in meeting demand for ATP?

Answer 9

Adrenalin increases rate of glycolysis, gluconeogenesis, and fatty acid release from adipocytes

Question 10

How are metabolic pathways controlled?

Answer 10

• The rate of enzyme controlled reactions is affected by product inhibition and the influence of signal molecules like hormones
• Hexokinase is inhibited by glucose 6-phosphate
• Hexokinase in the liver is less sensitive to inhibition than hexokinase in the muscle

Question 11

How do glucocorticoids affect metabolism?

Answer 11

They increase the synthesis of metabolic enzymes concerned with glucose availability.

Question 12

What are the two thpes of diabetes mellitus?

Answer 12

• Type 1 diabetes is where individuals fail to secrete insulin
• Type 2 diabetes is where individuals fail to respond appropriately to insulin

Question 13

What are the complications of diabetes?

Answer 13

• Hyperglycaemia causing progressive tissue damage
• Increase in fatty acids and lipoproteins
• Increase in ketone bodies causing acidosis
• Hypoglycaemia with the consequent of a coma.