Final answer:
Aldosterone decreases urinary output by increasing the reabsorption of sodium and water in the kidneys, which conserves water in the body and raises blood volume and pressure. Its release is part of the body's response to low blood sodium, high blood potassium, or decreased blood pressure and is involved in the renin-angiotensin-aldosterone system.
Step-by-step explanation:
The effects of the hormone aldosterone on urinary output are closely related to its role in regulating the balance of electrolytes and water in the body. Aldosterone causes the kidneys to increase the reabsorption of sodium ions and water from the filtrate into the blood, which in turn decreases the amount of urine produced.
This hormone is released in response to low blood sodium levels, high blood potassium levels, or decreased blood pressure and acts by stimulating the synthesis and activation of the sodium-potassium pump in the distal convoluted tubules and collecting ducts of the kidneys. As sodium is reabsorbed, water follows due to osmosis, leading to an increase in both blood sodium levels and blood volume, while conversely promoting the excretion of potassium.
Furthermore, aldosterone is involved in the renin-angiotensin-aldosterone system (RAAS), which is a critical regulatory system for blood pressure. In the event of low blood pressure, the juxtaglomerular apparatus of the kidney releases renin, leading to a series of reactions that ultimately promote the secretion of aldosterone, resulting in sodium and water reabsorption and an increase in blood pressure. The overall effect of aldosterone is therefore to conserve water in the body, and thus reduce urinary output.