Excretion Part 2 (10.2)

Question 1

Which organs in the body excrete waste?

Answer 1

• liver
• lungs
• kidneys
• skin

Question 2

Information about the liver:

Answer 2

• one of the largest organs in the body
• only organ capable of natural regeneration
• performs metabolic & homeostatic functions

Question 3

What are the key functions of the liver?

Answer 3

• filtering mechanism for foreign particulate
• synthesis & production of bile
• carbohydrate, protein & fat metabolism
• endocrine function
• iron & copper storage
• Vitamin A,B12, D, E, K storage
• detoxification

Question 4

What happens in amino acid catabolism?

Answer 4

• breakdown of AA’s occur by transmination & deamination
• NH4+ is a by - product, will be detoxified by the urea cycle
• detoxified (turn into urea)

Question 5

What happens in the ornithine cycle?

Answer 5

• ammonia = toxic
• ammonia = released during deamination, rapidly moved by the liver + converted to urea
• urea = synthesised by the liver + excreted by the kidneys
• some diffuses into the intestine, then is converted to ammonia by enteric bacteria

Question 6

What are xenobiotics?

Answer 6

substances not normally present in the body

Question 7

What is biotransformation?

Answer 7

• process of neutralizing xenobiotics by the liver

- modifying chemical constitution

Question 8

The liver plays a role in inactivation & excretion of hormones e.g. steroids. True or False?

Answer 8

True - it plays an important role.

Question 9

What are the steps in detoxification for drugs/ poisons?

Answer 9

• the drug is in the plasma
• phase 1, oxidation & reduction
• the drug is modified
• phase 2, conjugation
• drug conjugate = formed
• excretion

Question 10

What happens in the metabolism of alcohol?

Answer 10

• alcohol = absorbed into the gastrointestinal tract
• transported to the liver through the hepatic portal vein
• then by the following pathways:
• alcohol dehydrogenase system (ADH)
• microsomal ethanol oxidizing system (MEOS)
• catalase pathway (minor pathway)

Question 11

How does asian flush syndrome occur?

Answer 11

• alcohol is converted to acetaldehyde by ADH

- then from acetaldehyde to acetate by ALDH (genotype)

Question 12

What is deanimination?

Answer 12

• removal of an amino group from an amino acid or other compound

Question 13

What is transanimation?

Answer 13

• transfer of an animo group from one molecule to another