The Kidney- Unit 3.7 Flashcards
Name the main source of nitrogen containing wastes in animals:
Amino acid breakdown
Why do aquatic organisms excrete ammonia directly?
The ammonia quickly dilutes in the surrounding water, reducing its toxicity
What is the advantage of having an excretory product that is low toxicity, like urea?
It can remain in the body for longer
Explain the advantages that uric acid has over urea. (2)
It is virtually non-toxic.
Very little water required so is conserved.
What organism is uric acid excreted by?
Birds
What organism is urea excreted by?
Mammals
What does the skin excrete? (2)
Urea and other salts
What does the liver excrete?
Chemical waste in bile
What do the kidneys excrete? (3)
Urea, uric acid and ammonium salts
Where does deamination take place?
Loop of Henle
Describe deamination.
Excess amino acids are converted into ammonia, then into urea in the liver, and carried to the kidney to be filtered and excreted in urine. (amino group is removed)
What is homeostasis?
The ability to return to a set point whilst constant changes in body temperature, pH and water potential is occurring, maintaining a dynamic equilibrium. (regulating)
What is negative feedback in homeostasis?
Movement away from a set point (due to change in the internal environment) triggers a corrective action, counteracting the change, ensuring the set point is restored.
What does positive feedback do?
An effector amplifies the change to continue
Advantage of ammonia being soluble for fish?
Diffuses across gills easily
Does excreting ammonia use energy from the fish?
No
What are the kidney’s two main functions?
Excretion and osmoregulation
Is energy required for a bird to release uric acid?
Yes, a large amount
What are the properties of uric acid? (2)
Insoluble in water & non-toxic
Why is urea made?
Because excess amino acids cannot be stored
Name the three main components of a regulatory control system in the body. (along with input/output)
- Input
- –> receptor
- co-ordinator
- effector
- –> output (repeat)
What is ultrafiltration?
Filtering of small molecules out of the blood into the Bowman’s capsule under high pressure.
What 5 substances will be present in the (glomerular) filtrate for ultrafiltration?
Urea
Water
Salts
Glucose
Amino acids
Explain the effect on filtration rate during a large loss of blood from the body. (2)
If hydrostatic pressure decreases, so will filtration rate.
Less blood is available to move into the filtrate.
Name the part of the nephron which provides the osmotic gradient for reabsorption.
Loop of Henle
Which arteriole in the Loop of Henle is wider and which is narrower?
Wider- Afferent
Narrower- Efferent
Where does ultrafiltration occur?
In the glomerulus in the nephron.