Urea Cycle & Nitrogen Metabolism

Question 1

• In which species are the urea cycle and the Kreb’s cycle linked?

Answer 1

Most land animals & fish (not including birds and terrestrial reptiles)

Question 2

• What two pathways can lead to an excess of nitrogenous compounds within the body?

Answer 2

Diet proteins digestion/breakdown and the breakdown of skeletal muscle proteins

Question 3

What does the deamination of amino acids produce?

Answer 3

Alpha-keto acids & ammonium

Question 4

• What are glucogenic and ketogenic amino acids broken down too?

Answer 4

Glucogenic – glucose, ketogenic - lipids

Question 5

• What is significant about essential amino acids?

Answer 5

Their carbon skeletons cannot be synthesised and therefore they must be obtained through diet

Question 6

• What is the fate of ammonium?

Answer 6

Goes to the urea cycle

Question 7

• Where does urea enter and exit the renal tubules?

Answer 7

Urea flows out from the distal part of the collecting tubule, it enters back into the thin limbs of the loop of Henle

Question 8

• What does a high blood urea suggest?

Answer 8

That the renal clearance is affected (not a good marker in ruminants as urea is produced from ammonia by bacteria in the foramen)