Final answer:
Aldosterone is the steroid hormone secreted by the adrenal cortex that increases reabsorption of sodium and water in the kidneys, influencing blood volume and pressure.
Step-by-step explanation:
The steroid hormone secreted by the adrenal cortex which stimulates kidney salt reabsorption is Aldosterone. Aldosterone is often referred to as the "salt-retaining hormone" and plays a crucial role in the regulation of blood pressure by increasing the reabsorption of sodium ions (Na+) and water in the kidneys, which in turn increases blood volume and pressure. It also causes the excretion of potassium ions (K+), and this balance of minerals is essential for maintaining proper fluid balance and blood pressure.