Excretion, Homeostasis and the Liver

Question 1

Define excretion

Answer 1

the removal of toxic substances, waste products of metabolism and excess substances from organisms

Question 2

Define egestion

Answer 2

the passing of our undigested food as faeces through the anus

Question 3

What is the largest internal organ?

Answer 3

the liver

Question 4

What are the sections of the liver called?

Answer 4

lobes

Question 5

What are liver cells called?

Answer 5

hepatocytes

Question 6

Describe the gross structure of the mammalian liver

Answer 6

• Liver lobules (cylinders of hepatocytes arranged in rows and connected at the centre) are connected to:
• hepatic vein takes deoxygenated blood away from the liver and is attached to -> hepatic portal vein: contains products of digestion & hepatic artery: supplies oxygenated blood via Sinusoid capillaries.
• And bile duct: transports bile to gall bladder for storage.

Question 7

Outline the functions of the mammalian liver

Answer 7

• site of gluconeogenesis, glycolysis, glycogenesis
• stores glycogen
• deaminates excess amino acids, forming ammonia and organic acids. Acids can be respired or converted into glycogen. Ammonia is detoxified by addition of CO2 in ornithine cycle
• detoxifies chemicals e.g. converts alcohol to ethanal then acetic acid