Low pressure receptor zones
Low pressure receptor zones are areas with baroreceptors located in the venae cavae and the pulmonary arteries, and in the atria. They are also called volume receptors. These receptors respond to changes in the wall tension, which is proportional to the filling state of the low pressure side of circulation (below 60mmHg). Their impulses regulate the secretion of antidiuretic hormone (ADH/Vasopressin), renin and aldosterone. An elevated atrial pressure produces a decrease in ADH and aldosterone secretion. The decrease in vasopressin secretion results in an increase in the volume of urine excreted, serving to lower blood pressure. In addition, stretching of atrial receptors increases secretion of atrial natriuretic peptide (ANP), which promotes increased water and sodium excretion through the urine.
In the right atrium, the stretch receptors occur at the junction of the venae cavae. In the left atrium, the junction is at the pulmonary veins. Increasing stretch of the receptors stimulates both an increase in heart rate and a decrease in vasopressin (ADH) secretion from posterior pituitary.
- "Principles of medical physiology" by A Fonyo page 577