Atrial volume receptors

Atrial volume receptors, also known as cardiopulmonary receptors, are specialized sensory receptors located in the atria of the heart. These receptors play a crucial role in the regulation of blood volume and blood pressure by sensing changes in the stretching of the atrial walls, which reflect changes in blood volume within the heart. When activated, atrial volume receptors initiate reflexes that influence kidney function, heart rate, and vascular tone, contributing to the maintenance of circulatory homeostasis.

Function

Atrial volume receptors are mechanoreceptors that respond to the mechanical stretch caused by an increase in blood volume. When the blood volume in the atria increases, these receptors are activated and send signals through the vagus nerve to the central nervous system (CNS). This activation initiates several reflex responses known as the volume reflex or Bainbridge reflex. The primary outcomes of this reflex include:

• Modulation of the Renin-Angiotensin-Aldosterone System (RAAS), leading to alterations in renal sodium and water reabsorption, which can adjust blood volume and pressure.
• Inhibition of antidiuretic hormone (ADH) release, promoting diuresis and natriuresis to decrease blood volume.
• Adjustments in heart rate and strength of cardiac contractions to accommodate changes in blood volume.
• Regulation of sympathetic nervous system activity, affecting vascular tone and thus, blood pressure.

Clinical Significance

The function of atrial volume receptors has implications in various clinical conditions. For instance, in heart failure, the reduced effectiveness of these receptors contributes to fluid retention and edema. Understanding the role of atrial volume receptors can aid in the development of treatments targeting the modulation of their activity to manage conditions like hypertension and heart failure.

Research and Future Directions

Research into atrial volume receptors continues to uncover their complexities and the various pathways through which they influence cardiovascular and renal systems. Future studies are focused on identifying potential therapeutic targets within these pathways to treat diseases associated with volume overload and hypertension.

See Also

• Baroreceptor
• Heart failure
• Hypertension
• Renin-Angiotensin-Aldosterone System
• Vagus nerve