renin-angiotensin system

(noun)

A collection of hormones involved in the regulation of the body's blood pressure and water content.

Related Terms

Examples of renin-angiotensin system in the following topics:

  • Long-Term Renal Regulation

    • Consistent and long-term control of blood pressure is determined by the renin-angiotensin system.
    • A key modulator of blood viscosity is the renin–angiotensin system (RAS) or the renin–angiotensin–aldosterone system (RAAS); a hormone system that regulates blood pressure and water balance.
    • Plasma renin then carries out the conversion of angiotensinogen released by the liver to angiotensin I.
    • If the renin–angiotensin–aldosterone system is too active, blood pressure will be too high.
    • The figures outlines the origination of the renin-angiotensin pathway molecules, as well as effects on target organs and systems.

  • Regulation of Water Intake

    • Another way through which thirst is induced is through angiotensin II, one of the hormones involved in the renin-angiotensin system.
    • The renin-angiotensin system is a complex homeostatic pathway that deals with blood volume as a whole, as well as plasma osmolarity and blood pressure.
    • When the macula densa is stimulated by high osmolarity, The JGA releases renin into the bloodstream, which cleaves angiotensinogen into angiotensin I.
    • Note that the renin-angiotensin system, and thus thirst, can be caused by other stimuli besides increased plasma osmolarity or a decrease in blood volume.
    • Sympathetic nervous system stimulation and low blood pressure in the kidney's (decreased GFR) will stimulate the renin-angiotensin system as well, and will also cause an increase in thirst.

  • Regulation of Water Output

    • The hormones ADH (anti-diuretic hormone, also known as vasopressin) and aldosterone, a hormone created by the renin-angiotensin system play a major role in this.
    • Aldosterone is a steroid hormone (corticoid) produced at the end of the renin-angiotensin system.
    • To review the renin-angiotensin system, low blood volume activates the juxtaglomerular apparatus in a variety of ways, which secretes renin.
    • Renin cleaves angiotensin I from the liver produced angiotensinogen.
    • Overview of the renin-angiotensin system that regulates blood pressure and plasma osmolarity.

  • Developmental Changes in Fluids

    • Hormonal mechanisms including the renin-angiotensin system, aldosterone, and vasopressin are involved in modifying fetal renal excretion, reabsorption of sodium and water, and regulation of vascular volume.
    • The hypothalamic-neurohypophysial system plays a fundamental role in the maintenance of body fluid homeostasis by secreting arginine vasopressin (AVP) and oxytocin (OT) in response to a variety of signals, including osmotic and non-osmotic stimuli.
    • This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.
    • Overview of the renin-angiotensin system that regulates blood pressure and water (fluid) balance.

  • Sodium Balance Regulation

    • Extra sodium is lost from the body by reducing the activity of the renin-angiotensin-aldosterone system which leads to increased sodium loss from the body.
    • A low renal perfusion pressure stimulates the release of renin, which forms angiotensin I which is converted to angiotensin II.
    • The perfusion pressure to the adrenal gland has little direct effect on aldosterone secretion and the low blood pressure operates to control aldosterone via the renin angiotensin system.
    • In addition to aldosterone and angiotensin II other factors influence sodium excretion.
    • Regulation of sodium via the hormones renin, angiotensin, and aldosterone.

  • Nonrespiratory Air Movements

    • ACE (angiotensin converting enzyme) is an enzyme secreted by the endothelial cells of the capillaries in the lungs. 
    • ACE converts angiotensin I into angiotensin II, which are two important hormones in the renin-angiotensin feedback loop of the renal system.
    • The epithelial cells and macrophages of the lungs secrete many molecules that have immune system functions.
    • They can damage and inhibit pathogens and are considered a barrier component of the immune system.
    • The renin-angiotensin-aldosterone system is dependent on ACE from the lungs to regulate blood pressure.

  • Adrenal Cortex

    • The cortex is regulated by neuroendocrine hormones secreted by the pituitary gland which are under the control of the hypothalamus, as well as by the renin-angiotensin system.
    • The major stimulus to produce aldosterone is angiotensin II while ACTH from the pituitary only produces a transient effect.
    • Angiotensin is stimulated by the juxtaglomerular cells when renal blood pressure drops below 90 mmHg.
    • Its secretion is regulated by the oligopeptide angiotensin II (angiotensin II is regulated by angiotensin I, which in turn is regulated by renin).

  • Other Hormone-Producing Structures

    • Many tissues within the body release hormones including the placenta, kidneys, digestive system, and adipose tissue.
    • The kidneys secrete a variety of hormones, including erythropoietin, and the enzyme renin.
    • Part of the renin-angiotensin-aldosterone system, renin is an enzyme involved in the regulation of aldosterone levels.
    • ANH acts to reduce the water, sodium, and adipose loads on the circulatory system, thereby reducing blood pressure.
    • There are at least five hormones that aid and regulate the digestive system in mammals (See Figure 2 for site of hormone actions).

  • Congestive Heart Failure

    • Binding to alpha-1 receptors results in systemic arterial vasoconstriction.
    • Reduced perfusion (blood flow) to the kidneys stimulates the release of renin – an enzyme that catalyzes the production of the potent vasopressor angiotensin .
    • Angiotensin and its metabolites cause further vasoconstriction, and stimulate increased secretion of the steroid aldosterone from the adrenal glands.
    • Reduced perfusion (blood flow) to the kidneys stimulates the release of renin, an enzyme that catalyzes the production of the potent vasopressor angiotensin.

  • Overview of the Urinary System

    • The renal system, which is also called the urinary system, is a group of organs in the body that filters out excess fluid and other substances from the bloodstream.
    • The  renal system has many functions.
    • Kidneys are the most complex and critical part of the urinary system.
    • Kidneys play a very large role in human osmoregulation by regulating the amount of water reabsorbed from glomerular filtrate in kidney tubules, which is controlled by hormones such as antidiuretic hormone (ADH), renin, aldosterone, and angiotensin I and II.
    • Besides ADH secretion, the renin-angiotensin feedback system is critically important to maintain blood volume and blood pressure homeostasis.