Unit D3

Question 1

State the vessels and their function within the liver (6 marks).

Answer 1

Hepatic artery: carries oxygenated blood to the liver
Hepatic vein: carries deoxygenated blood to the heart from the liver
Hepatic portal vein: carries nutrient rich blood from intestinal tract

Question 2

State 3 functions of the liver. (3 marks)

Answer 2

• storage and controlled release of key nutrients (e.g. glycogen, cholesterol, triglycerides)
  -detoxification of potentially harmful ingested substances (e.g. amino acids, medications, alcohol)
  -produces plasma proteins that function to maintain sustainable osmotic conditions within the bloodstream
  -breakdown of erythrocytes and the production of bile salts

Question 3

What is the make up of plasma proteins. (3 marks)

Answer 3

-Albumins regulate the osmotic pressure of the blood
- Globulins participate in the immune system (i.e. immunoglobulins) and also act as transport proteins
- Fibrinogens (involved in clotting)
- other proteins utilised in other human processes.

Question 4

Describe the structure of the liver.

Answer 4

Hepatic artery: carries oxygenated blood to the liver
Hepatic vein: carries deoxygenated blood to the heart from the liver
Hepatic portal vein: carries nutrient rich blood from intestinal tract
Kupffer cells: breaks down erythrocytes via engulfment.

Liver is composed into different lobules with sinusoids connecting all elements together into central vein.

Question 5

Compare and contrast the structure of capillaries to sinusoids. (3 marks)

Answer 5

Sinusoids contain an incomplete basement membrane, capillaries do.
Sinusoids are fenestrated, capillaries are not.
Sinusoids contain fewer tight junctions allowing larger macromolecules to pass through,

Question 6

Explain the breakdown of erythrocytes and their regeneration. (7 marks)

Answer 6

Red blood cells have a cell lifetime of around 120 days. Kupffer cells are specialised phagocytes that breaks haemoglobin into heme and globin. globin is broken down by peptidases and their amino acids are reused in protein synthesis. Heme is utilised in the production of bilirubin and iron. Bilirubin is used in the production of bile and is moved into the gall bladder. Iron is transported by ferrin into the bone marrow where the iron acts as the prosthetic group in a new haemoglobin.

Question 7

What is jaundice and how is it caused? (4 marks)

Answer 7

Jaundice is a condition provoked by an excess amount of bilirubin within the body, bilirubin normally associates with other chemicals to become bile and is stored within the gall bladder. It can be caused by liver disease, an obstruction within the gall bladder, and damage to erythrocytes (excess breakdown of haemoglobin)