Liver

Question 1

What are the major vessels supplying the liver?

Answer 1

Hepatic artery - supplies 20% blood
Hepatic portal vein Carries water soluble products of digestion to the liver

Question 2

What is the average blood flow of liver?

Answer 2

1350ml/min

Question 3

What is a liver lobule?

Answer 3

Liver has 50,000-100,000 lobules. they consist of a heptic cellular plate. In the centre, there is a vein which branches from the hepatic vein (carries blood to vena cava). Blood flows from hepatic portal vein, between the hepatocytes via sinusoids.

Question 4

What is metabolic zonation?

Question 5

How is glucose stored and synthesised in the liver?

Answer 5

Cannot be synthesised from liver fat stores as they are small, so, the liver maintains a store of glucose from glycogen. Glycogen is a branched ps which creates more ends for enzymes to operate, they are stores in granules. Glycogen is very hydrated and therefore weighs down the liver.

Question 6

What are two hormones having a big effect on the liver?

Answer 6

Insulin from beta cells and glucagon from alpha cells in the pancreas. Insulin is released when plasma glucose is to high.

Question 7

What is carbohydrate metabolism by the liver?

Answer 7

Keeping glucose levels at 5mmol/L, especially in the brain, it cannot drop below 3mmol/L.

Question 8

How does glucose enter the bloodstream (3 routes)?

Answer 8

Absorption from SI, glycogenolysis - breakdown of glycogen, glucogenesis - synthesis of glucose in the liver from AAs, lactate and glycerol.

Question 9

What is glycogenesis?

Question 9

What is protein metabolism by the liver?

Answer 9

AAs are received by the hepatic portal vein. AA oxidation provides the livers energy requirements. The liver is the only organ that can eliminate nitrogen from AAs via deamination (removal of amine group NH2) from ammonia (NH3).

Question 10

What is catabolism?

Answer 10

The uptake of AAs by the AA transporters and they can enter the AApool, protein synthesis, transamination (removing one amino group from one AA to another), and deamination.

Question 11

How does exercise impact the liver?

Answer 11

Energy expenditure for the whole body increases.

Question 12

How does cholesterol synthesis in the liver occur?

Answer 12

It is absorbed by the SI (exogenous cholesterol) and the liver can synthesise endogenous cholesterol. It is synthesised from multiple molecules of acetyl-CoA.

Question 13

How does bile salts synthesis occur?

Answer 13

They are composed of bile acids, cholesterol and phosphatidylcholine. Bile salts digest lipids.

Question 14

How does lipoprotein synthesis occur?

Answer 14

Made from cholesterol and phospholipids (also synthesised in liver from fatty acids), lipoproteins are incorporated into cell membranes.

Question 15

What are phospholipids used for?

Answer 15

Used for lipoprotein synthesis, lipid transport, structural role in membranes, synthesise thromboplastin for the clotting process, synthesise sphingomyelin which insulates neurones.

Question 16

How does exercise lead to the release of nitrogen and what happens to it?

Answer 16

Increased protein breakdown from skeletal muscle increases AAs in circulation. Transported via plasma to the liver. recycled in the liver to make glucose, and the deaminated nitrogen from the amino group is converted and excreted as urea via the kidney in urine.

Question 17

How does exercise affect fat mobilisation?

Question 18

How does exercise impact the liver and holistics?

Answer 18

Liver metabolism lowers as there is reduced blood flow due to it going to skeletal and cardiac muscle.