Antidiuretic hormone (ADH)

Definition

Antidiuretic hormone (ADH), also known as vasopressin, is a peptide hormone produced by the hypothalamus and released by the posterior pituitary gland. It plays a critical role in regulating water balance in the body by promoting water reabsorption in the kidneys, thus affecting blood pressure and overall fluid homeostasis.

5 Must Know Facts For Your Next Test

1. ADH increases water permeability in the collecting ducts of the kidneys, allowing for more water to be reabsorbed back into the bloodstream.
2. The secretion of ADH is primarily triggered by increased plasma osmolality or decreased blood volume, signaling the body to conserve water.
3. Alcohol consumption can inhibit the release of ADH, leading to increased urine production and potential dehydration.
4. In conditions like diabetes insipidus, insufficient ADH production results in excessive urination and thirst due to the inability of the kidneys to reabsorb water effectively.
5. ADH also has vasoconstrictive properties, meaning it can narrow blood vessels and raise blood pressure when necessary.

Review Questions

• How does ADH function in regulating kidney function and maintaining fluid balance?
  • ADH functions by binding to receptors in the kidneys, specifically in the collecting ducts, which enhances their permeability to water. This allows for more water to be reabsorbed back into the bloodstream, reducing urine output and helping to maintain fluid balance. The regulation of ADH ensures that when the body is dehydrated or when plasma osmolality is high, water retention occurs to restore homeostasis.
• Discuss the physiological triggers for ADH release and how these mechanisms help maintain homeostasis.
  • ADH release is primarily triggered by increases in plasma osmolality or decreases in blood volume. Specialized osmoreceptors in the hypothalamus detect changes in osmolality, signaling for ADH secretion. This hormone then acts on the kidneys to promote water reabsorption, which helps dilute excess solutes and restore blood volume, maintaining overall homeostasis within the body.
• Evaluate the implications of impaired ADH function in relation to conditions like diabetes insipidus and its impact on overall health.
  • Impaired ADH function, such as in diabetes insipidus, leads to an inability to concentrate urine due to insufficient hormone levels or receptor responsiveness. This results in excessive urination (polyuria) and extreme thirst (polydipsia), causing dehydration and electrolyte imbalances. Such conditions can significantly impact an individual's quality of life and require careful management to avoid complications associated with dehydration and imbalanced fluid levels.

Related terms

Kidneys: Organs that filter waste products from the blood and regulate fluid balance, electrolytes, and blood pressure.

Hypothalamus: A region of the brain that controls the release of hormones from the pituitary gland and regulates various physiological functions, including thirst and fluid balance.

Osmoregulation: The process by which organisms regulate the osmotic pressure of their body fluids, maintaining homeostasis of water and electrolytes.