Low pressure baroreceptors are baroreceptors that relay information derived from blood pressure within the autonomic nervous system. They are stimulated by stretching of the vessel wall. They are located in large systemic veins and in the walls of the atria of the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

, and pulmonary vasculature. Low pressure baroreceptors are also referred to as volume receptors and cardiopulmonary baroreceptors.Armstrong, Maggie, et al. ''Physiology, Baroreceptors - Statpearls - NCBI Bookshelf''. 9 Mar. 2022, https://www.ncbi.nlm.nih.gov/books/NBK538172/.

Structure

There are two types of cardiopulmonary baroreceptors. Type A receptors and Type B receptors are both within the atria of the

. Type A receptors are activated by wall tension, which develops by atrial contraction during ventricular diastole. Type B receptors are activated by wall stretch, which develops by atrial filling during

ventricular systole The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following ...

. In the

right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

, the stretch receptors occur at the junction of the

venae cavae In anatomy, the venae cavae (; singular: vena cava ; ) are two large veins (great vessels) that return deoxygenated blood from the body into the heart. In humans they are the superior vena cava and the inferior vena cava, and both empty into the ...

. In the

left atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

, the junction is at the

pulmonary veins The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four ''main pulmonary veins'', two from each lung that drain into the left atrium of the heart. The pulmonary vei ...

Function

Low pressure baroreceptors are involved in regulation of the blood volume. The blood volume determines the mean pressure throughout the system, especially venous side where most of the blood is held. Low pressure baroreceptors have both circulatory and renal effects, which produce changes in hormone secretion. These secretions can effect the retention of salt and water as well as influencing the intake of salt and water within the

kidneys The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

. The renal will allow the receptors to change the longer-term mean pressure.Ishii, Kei, et al. “Differential Contribution of Aortic and Carotid Sinus Baroreflexes to Control of Heart Rate and Renal Sympathetic Nerve Activity.” ''The Journal of Physiological Sciences : JPS'', U.S. National Library of Medicine, 10 July 2015, https://pubmed.ncbi.nlm.nih.gov/26159318/. Through the vagal nerve, impulses transmits from the atria to the vagal center of the

medulla Medulla or Medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ovary * Medulla of t ...

. This causes a reduction in the sympathetic outflow the kidney, which results in decreased renal blood flow and decreased urine output. This same sympathetic outflow is increased to the

sinus node The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approxima ...

in the atria, which causes increased heart rate/cardiac output. These cardiopulmonary receptors also inhibits vagal stimulation in the vasoconstrictor center of the medulla resulting in decreased release of

angiotensin Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adren ...

, aldosterone, and

vasopressin Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then trave ...

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References

{{DEFAULTSORT:Low Pressure Receptor Zones Sensory receptors