Atrial volume receptors
Atrial volume receptors are low pressure baroreceptors that are found in the atria of the heart. They are myelinated vagal fibres in the endocardium found at the junction between atria and the vena cava/pulmonary vein.
When these receptors detect a blood volume decrease in the atria, a signal is transmitted from the receptors to the hypothalamus in the brain. The hypothalamus, in turn, increases the production of vasopressin. These receptors also cause a renal vasodilation, resulting in increase of the water amount in the glomerular filtrate which, combined with the increased production of vasopressin by the hypothalamus, will cause water retention in urine. This increases the blood volume, resulting in the increase of blood pressure.
There are two types, type A is activated by atrial wall tension in atrial contraction, type B is activated by atrial stretch during atrial filling.
They can display hysteresis.
