Excretion Flashcards
1
Q
excretion
A
the removal of metabolic waste products from the body
2
Q
metabolic waste
A
unwanted or toxic by products from cellular reactions
3
Q
egestion
A
removal of undigested food via defecation
4
Q
examples of metabolic waste (4)
A
- water
- CO2
- nitrogen from excess amino acids (produces urea)
- bile pigments (broken down Hb)
5
Q
organs involved in excretion (4)
A
- lungs
- skin
- kidneys
- liver
6
Q
how are amino acids converted to urea?
A
- excess amino acids transported to liver
- deamination occurs (amine group removed)
- amino acid + O2 –> keto acid + ammonia
- keto acid either used in respiration or stored as carbs or fat
- ammonia converted to urea via ornithine cycle:
- ammonia + CO2 –> urea + water
- 2NH3 + CO2 –> CO(NH2)2 + H2O
- urea transported to kidneys (dissolved in plasma)
7
Q
why is ammonia converted to urea? (2)
A
- urea is less toxic
- urea is less soluble
8
Q
two functions of the kidneys
A
- excretion (urea, excess water, salts, creatine)
- homeostasis (osmoregulation, [salt] and pH control)
9
Q
A
