Low pressure receptor zones
Encyclopedia
Low pressure receptor zones are areas with baroreceptors
located in the venae cavae
and the pulmonary veins, 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.
Baroreceptor
Baroreceptors are sensors located in the blood vessels of several mammals. They are a type of mechanoreceptor that detects the pressure of blood flowing through them, and can send messages to the central nervous system to increase or decrease total peripheral resistance and cardiac output...
located in the venae cavae
Venae cavae
The superior and inferior vena cava are collectively called the venae cavae. They are the veins that return deoxygenated blood from the body into the heart. They both empty into the right atrium....
and the pulmonary veins, 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
Renin
Renin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
and aldosterone
Aldosterone
Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release of potassium in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that...
. An elevated atrial pressure produces a decrease in ADH
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
and aldosterone secretion. The decrease in vasopressin
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
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
Atrial natriuretic peptide
Atrial natriuretic peptide , atrial natriuretic factor , atrial natriuretic hormone , or atriopeptin, is a powerful vasodilator, and a protein hormone secreted by heart muscle cells. It is involved in the homeostatic control of body water, sodium, potassium and fat...
(ANP), which promotes increased water and sodium excretion through the urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
.
In the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...
, the stretch receptors occur at the junction of the venae cavae. In the left atrium
Left atrium
The left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
, 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
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
) secretion from posterior pituitary.