EXCRETION

Question 1

What is excretion?

Answer 1

The process of removing metabolic waste from cells.

Question 2

Breaking down of amino acids.

Answer 2

1. Amine groups removed from amino acids via deamination, producing ammonia and organic acids.
2. Organic acids used for ATP production or stored as glycogen.
3. Ammonia combines with CO2 to form urea via the ornithine cycle, occurring in mitochondria of liver cells.
4. Urea excreted from liver cells into bloodstream, filtered out body via kidneys in urine.

Question 3

Substances detoxified by liver.

Answer 3

• Amino acids, hydrogen peroxide (catalase splits it into oxygen and water to prevent cell damage), Alcohol (alcohol dehydrogenase breaks down ethanol into ethanal into ethanoate), paracetamol (prevents toxicity to liver and kidneys), insulin (regulate blood glucose conc).

Question 4

Liver and blood glucose.

Answer 4

• Converting excess glucose to glycogen for storage.
• Stores glycogen granules in its cells.
• Releases glucose into the bloodstream by breaking down glycogen into glucose.

Question 5

Structure of liver.

Answer 5

• Hepatic artery- supplies oxygenated blood.
• Hepatic portal vein- Nutrient rich blood from intestines.
• Hepatic vein- Deoxygenated blood to heart.
• Bile canaliculus- links to branch of bile duct.
• Bile duct- Carries bile to gall bladder to be stored.
• Hepatocytes- Liver cells.
• Kupfer cells- Destroy and ingest pathogens.