What is the primary hormone responsible for Na+ resorption during hemorrhage?

The primary hormone responsible for sodium resorption during hemorrhage is aldosterone. In response to decreased blood volume and blood pressure that can occur during hemorrhage, the body activates the renin-angiotensin-aldosterone system (RAAS). When blood volume drops, renin is released from the kidneys, leading to the formation of angiotensin II. Angiotensin II stimulates the adrenal cortex to secrete aldosterone.

Aldosterone enhances the reabsorption of sodium (Na+) in the renal tubules, particularly in the distal convoluted tubule and collecting duct. This sodium retention is crucial during hemorrhagic events, as it helps to retain water in the body through osmosis, which increases blood volume and helps to restore blood pressure.

While antidiuretic hormone (ADH) plays a role in water retention and can assist in maintaining blood volume, it does not primarily act to resorb sodium. Cortisol can promote sodium retention but is generally not the primary hormone involved in acute situations like hemorrhage. Insulin is not directly involved in sodium resorption but rather plays a role in glucose metabolism.

Thus, aldosterone is the key hormone in this context, primarily facilitating sodium resorption to counteract the effects of hemorr