The renin-angiotensin system (RAS), also known as renin-angiotensin-aldosterone system (RAAS) is well-known for its role in regulating blood pressure, fluid volume, and capillary perfusion. It is one of the most important systems studied by those interested in the cardiovascular system and those involved in the pathogenesis of heart and renal diseases. The renin-angiotensin system exists in two frameworks: a circulating system and multiple local, tissue-specific systems. Local RAS have been found in the pancreas, heart, brain, vessels, adrenal glands, and reproductive tracts (1). In the classical RAS pathway, the crucial hormone angiotensin (Ang) II is formed by cleavage of angiotensin I. The effects of Ang II are mainly carried out by two receptors: angiotensin II receptor type 1 (AT1R) and angiotensin receptor type two (AT2R). The physiological attributes and regulations by Ang II vary based on tissues. For example, the brain RAS regulates thirst, salt appetite, sympathetic activation, and vasopressin release while kidney RAS regulates fibrosis and sodium retention.
In this paper, an overview of the components of the circulatory renin-angiotensin system and their productions will be given, along with evidence in support of a cardiac RAS. The local RAS of the heart deviate from the classical pathway in two ways, one being other sources of productions such as myocytes and fibroblasts that differ from renal or neural RAS, and the other being its functions and roles that distinguish it from other tissue RAS. Based on conducted research, the renin-angiotensin system is a critical component that contributes to the progression of heart failure (2). This has spurred further research on suppression of RAS in order to control the rate o...
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Nitric oxide is a gaseous, diatomic molecule that plays an important role as a mediator of cardiac function, working largely as a vasodilator in the cardiovascular system. Nitric oxide is synthesized by a family of enzymes known as nitric oxide synthases (...
Renin angiotensin system activation: Because of decreased blood flow to the kidneys the compensatory mechanisms activate to hold on to sodium and water. When the Blood flow is decreased Angiotensin II is released causing vasoconstriction
In this activity Renal Response to Altered Blood Pressure was recorded. The glomerular capillary pressure and GFR; GFR and pressure increased when both arteriole radii changes were implemented simultaneously with the low blood pressure condition. Increasing the afferent radius had a greater effect than decreasing the efferent radius because there was a greater increase in glomerular pressure.
The cardiovascular system is divided into two systems a pulmonary and a systemic. Pulmonary division- blood flows from the heart to alveolar capillaries and back to the heart. Systemic division- blood flows from heart to every capillary “except alveolar” and back to heart.
Aldosterone is in a class of hormones called mineralocorticoids which is also produced by the adrenal glands. The main functions of aldosterone are to help to maintain blood pressure and helping the kidneys retain needed sodium and excrete unwanted potassium to maintain the balance of water and salt in the body.
This only keeps the blood moving for a short while. The heart muscle walls weaken and are unable to pump as strongly. This makes the kidneys respond by causing the body to retain fluid and sodium. When the body builds up fluids, it becomes congested. Many conditions can cause heart failure, and they include coronary artery disease, heart attack, cardiomyopathy, and conditions that overwork the heart.
The causes of hypertension are unknown. However; hypertension can be classified into two categories primary and secondary. Primary (essential) hypertension is increas...
" Journal of Clinical Hypertension 13.5 (2011): 351-56. EBSOHost.com - a. Web. The Web.
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
There are generally two categories of hypertension, primary hypertension and secondary hypertension. The causes of primary hypertension are usually unknown and it develops gradually over the years. As for secondary hypertension, the causes are mainly underlying other health problems and it develops in a sudden of time. (The Healthline Editorial Team 2013) First of all, hypertension can be related to renin-angiotensin-aldosterone system (RAAS). Renin is an enzyme secreted mainly via the juxtaglomerular apparatus of the kidney when the sodium retention and water retention are reduced in the blood. (Beevers, Lip, and O'Brien 2001) Renin will bind to a substrate which is angiotensinogen and form angiotensin I which is an inactive peptide. (Foëx and Sear 2004) After that, angiotensin I will be rapidly converted to an active peptide angiotensin II by angiotensin-converting enzyme (ACE) in lungs. As a result, vasoconstriction occurs due to presence of angiotensin II and this increases the blood pressure. Moreover, angiotensin II can stimulate the releasing of aldosterone by adrenal glands. Secretion of aldosterone raises the blood pressure by reabsorbing sodium salts and water to increase sodium and water retentions. (Beevers, Lip, and O'Brien 2001)
Staff, H. (2012, July 6). Heart Murmur - Good Health by Seton. Retrieved February 26, 2014, from http://www.goodhealth.com/health_a_to_z/health_library/health_topics/heart_problems/heart_murmur/
RAAS (Renin Angiotensin Aldosterone System) plays a role in the homeostatic process such as blood pressure and fluid volume control1. Renin is secreted in the blood from cells that are lining the glomeruli of the kidneys. The renin-secreting cells are sensitive to changes in blood flow and blood pressure. Angiotensinogen, a glycosylated protein that is primarily synthesized and secreted by the liver as well as other tissues is the sole precursor for angiotensin peptide. Renin catalyzes the conversion of a plasma protein called angiotensinogen into a decapeptide (consisting of 10 amino acids) called angiotensin I. An enzyme in the serum called angiotensin-converting enzyme (ACE) then converts angiotensin I into an octapeptide (consisting of
The heart is a pump with four chambers made of their own special muscle called cardiac muscle. Its interwoven muscle fibers enable the heart to contract or squeeze together automatically (Colombo 7). It’s about the same size of a fist and weighs some where around two hundred fifty to three hundred fifty grams (Marieb 432). The size of the heart depends on a person’s height and size. The heart wall is enclosed in three layers: superficial epicardium, middle epicardium, and deep epicardium. It is then enclosed in a double-walled sac called the Pericardium. The terms Systole and Diastole refer respectively and literally to the contraction and relaxation periods of heart activity (Marieb 432). While the doctor is taking a patient’s blood pressure, he listens for the contractions and relaxations of the heart. He also listens for them to make sure that they are going in a single rhythm, to make sure that there are no arrhythmias or complications. The heart muscle does not depend on the nervous system. If the nervous s...
(2013, July 8). Trauma Emergencies. Retrieved from https://ambulance.qld.gov.au/docs/09_cpg_trauma.pdf renin-angiotensin system. (2014). In Encyclopaedia Britannica.
In the US, heart attacks kill more people than any other single cause. Many of the deaths are caused by electrical disturbances in a damaged heart that cause it to fibrillate (Pool). Despite current overwhelming interest in the operations of the human heart, for most of history the human heart has been regarded as a "forbidden organ too delicate to tamper with" (NOVA). In fact, it might have remained so, were it not for World War II where military doctors, faced with massive numbers of injuries ushered the world into our current medical trajectory.