Which of the following factors will enhance ADH release?
a. Increase in ECF volume
b. Decrease in ECF volume
c. Decrease in ECF osmolality
d. Increase in ECF osmolality

Verified step by step guidance

1. Understand that ADH (antidiuretic hormone) release is primarily regulated by changes in extracellular fluid (ECF) osmolality and volume.
2. Recall that an increase in ECF osmolality means the blood is more concentrated, which typically stimulates ADH release to promote water retention and dilute the blood.
3. Recognize that a decrease in ECF volume (such as from blood loss or dehydration) also stimulates ADH release to conserve water and maintain blood pressure.
4. Note that an increase in ECF volume usually suppresses ADH release because the body has enough fluid and does not need to retain more water.
5. Understand that a decrease in ECF osmolality (more dilute blood) reduces the need for ADH release, as the body does not need to conserve water.

Key Concepts

Antidiuretic Hormone (ADH) Function

ADH, also known as vasopressin, regulates water balance by increasing water reabsorption in the kidneys. It is released in response to changes in blood volume and osmolality to maintain homeostasis, preventing dehydration or overhydration.

Extracellular Fluid (ECF) Volume and ADH Release

A decrease in ECF volume, such as during blood loss or dehydration, stimulates ADH release to conserve water and restore volume. Conversely, an increase in ECF volume typically suppresses ADH secretion since the body has sufficient fluid.

ECF Osmolality and ADH Regulation

ADH release is highly sensitive to ECF osmolality; an increase in osmolality (higher solute concentration) triggers ADH secretion to retain water and dilute the solutes. A decrease in osmolality reduces ADH release, promoting water excretion.