Homeostasis is essential for maintaining a constant internal environment in the human body.
The diagram below shows a simplified diagram of a single nephron, the functional unit of the kidney.
a.[2]
Describe what is meant by the term homeostasis and explain why maintaining a stable blood water potential (osmotic balance) is critical for the survival of red blood cells.
b.[4]
With reference to regions A and B in the diagram, describe what happens to amino acids, red blood cells, and urea as they pass through the kidney.
c.[4]
During a period of heavy exercise on a hot day, a person can become dehydrated. Explain how the secretion of ADH (antidiuretic hormone) affects region C, and how this alters the volume and concentration of the urine produced.