Role of liver

Question 1

What is the role of liver in carbohydrate metabolism

Answer 1

Glucose absorbed into the blood capillaries at the small intestine is brought via the hepatic portal vein to the liver

Question 2

What is the role of liver in fat digestion

Answer 2

1. The liver converts excess carbohydrates to fats
2. The liver removes cholesterol from blood and break it down, or when necessary, synthesizing it
3. The liver aids the breakdown of fats into fatty acid and glycerol to be used for respiration when glucose is in short supply

Question 3

What is the role of liver in the breakdown of red blood cells

Answer 3

Red blood cells are engulfed by and broken down in the macrophages in the liver and spleen, releasing haemoglobin. Further breakdown of haemoglobin in the liver results in heme and globin
Globin is the protein part of the molecule and is broken down to its individual amino acids
Iron is removed from the heme and the remaining part of the molecule is converted to biliverdin, which is then converted to bilirubin (Bile pigment excreted in bile)
Iron is stored in the liver and reused

Question 4

What is the role of liver in the metabolism of amino acids and the formation of urea

Answer 4

Excess amino acids are brought to the liver to be deaminated.
(The Nitrogen-containing amino part of the amino acids is removed, forming ammonia and changed to urea to be excreted by the kidneys in urine)
The carbon-containing compound of the deaminated amino acids enters the pathway of aerobic respiration to produce ATP. It may also be converted to glucose and stored as glycogen in liver and muscles

Question 5

What are some actions to reduce blood glucose concentration back to set-point

Answer 5

• By increasing the permeability of the cell membrane to glucose thereby increasing the rate of glucose uptake by cells via facilitated diffusion
• By stimulating the condensation of excess glucose the glycogen for for storage in liver and muscles
• By promoting conversion of carbohydrates to fats
• By causing an increased oxidisation of glucose during respiration

Question 6

What happens to blood glucose levels when they are very low, low and very high

Answer 6

Very low
- The brains are adversely affected, leading to coma
Starvation
- The glycogen in the liver is broken down to glucose
(Stimulated by the hormone glucagon)
Very high
- Excess glucose is excreted by the kidney in urine