Question 1a
Outline the role of the kidneys in homeostasis. [3]
Answer:
Regulation of Water Balance (Osmoregulation)
- Purpose: Controls the amount of water in the body to maintain stable conditions.
- Mechanism: Kidneys adjust water reabsorption based on the body’s hydration level.
- Examples:
- Dehydration: More water is reabsorbed, leading to concentrated (dark) urine.
- Excess Hydration: Less water is reabsorbed, resulting in dilute (light) urine.
2. Excretion of Waste Products
- Purpose: Removes harmful waste products from the blood.
- Mechanism: Kidneys filter out metabolic wastes, especially urea (from protein breakdown).
- Importance: Prevents toxic buildup of waste products, helping to maintain chemical stability in the blood.
3. Regulation of Ion Concentrations and Blood pH
- Keeps pH around 7.4 to support enzyme function and metabolic processes.
- Purpose: Maintains stable ion levels and pH, crucial for cellular function.
- Mechanism:
- Electrolyte Balance: Adjusts levels of ions like sodium, potassium, and calcium.
- pH Balance: Excretes hydrogen ions (H⁺) and reabsorbs bicarbonate ions (HCO₃⁻) to regulate blood pH.
- Examples:
- Keeps pH around 7.4 to support enzyme function and metabolic processes.