In renal tubules, aldosterone increases

Options

A. Absorption of `K^(+), H^(+)` and elimination of `Na^(+), H_(2)O`
B. Absorption of `Na^(+), H_(2)O` and elimination of `K^(+), PO_(4)^(3-)`
C. Absorption of `Na^(+), H_(2)O, K^(+), PO_(4)^(3-)`
D. Elimination of `Na^(+), H_(2)O, K^(+), PO_(4)^(3-)`

Answer

### Step-by-Step Solution:

1. **Understanding Aldosterone Function**: Aldosterone is a hormone produced by the adrenal cortex that plays a critical role in regulating sodium and potassium levels in the body. It primarily acts on the renal tubules in the kidneys.

2. **Trigger for Aldosterone Release**: The release of aldosterone is stimulated by a decrease in glomerular blood pressure or glomerular filtration rate (GFR). This decrease activates juxtaglomerular cells to release renin.

3. **Renin-Angiotensin-Aldosterone System (RAAS)**: Renin converts angiotensinogen (a protein produced by the liver) into angiotensin I, which is then converted to angiotensin II. Angiotensin II has multiple effects, including stimulating the adrenal cortex to release aldosterone.

4. **Effects of Aldosterone**: Once released, aldosterone acts on the distal convoluted tubules and collecting ducts of the kidneys. Its main effects include:
- **Increased Absorption of Sodium (Na+)**: Aldosterone promotes the reabsorption of sodium ions from the renal tubules back into the bloodstream.
- **Increased Absorption of Water (H2O)**: The reabsorption of sodium also leads to the reabsorption of water, which helps to increase blood volume and blood pressure.
- **Increased Elimination of Potassium (K+)**: Aldosterone promotes the secretion of potassium ions into the renal tubules for elimination in urine.
- **Increased Elimination of Phosphate (PO4^3-)**: Aldosterone also influences the excretion of phosphate ions.

5. **Conclusion**: Therefore, in renal tubules, aldosterone increases the absorption of Na+ and H2O while promoting the elimination of K+ and PO4^3-. This mechanism is crucial for maintaining electrolyte balance and regulating blood pressure.

### Final Answer:
In renal tubules, aldosterone increases the absorption of Na+ and H2O and the elimination of K+ and PO4^3-.

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