RAAS System
The renin-angiotensin-aldosterone system (RAAS) consists of a complex endocrine regulatory pathway and several less studied local autocrine/paracrine systems. RAAS is an important part of many pathologic conditions including hypertension, heart failure, and renal disease.
The classical endocrine RAAS is activated predominantly by decrease in renal blood flow. This system works primarily through the heart, blood vessels, and Kidneys to regulate blood pressure; and controls water and electrolyte balance.[figure 1] The RAAS contributes to chronic kidney disease(CKD) progression in part via blood pressure-mediated kidney damage. Angiotensin II, the primary effector agent of RAAS system, is a vasoconstrictor with a predominant effect
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2005) Local RAAS has been implicated as a key player in the pathogenesis of cardiovascular and renal diseases. Intrarenal RAAS is activated early in diabetic nephropathy, the leading cause of CKD.(Siragy and Carey 2010) Intracardiac RAAS may contribute to myocardial hypertrophy and remodeling.(Hayashida et al. 1993) Production of Aldosterone and Angiotensin Converting Enzyme (ACE) and selective downregulation of specific angiotensin II receptors has been observed in the failing heart(Mizuno et al. 2001)(Silvestre et al. 1999) (Asano et al. 1997)(Haywood et al. 1997)(Zisman et al. 1998). In addition to their direct effects, RAAS elements may also have indirect pathological effects through influencing factors like sympathetic activity(Grassi et al. 1997)(Dibner-Dunlap et al. 1996)(Latini 2002) level of kinins(Witherow et al. 2001), endothelial function(Hornig et al. 1998)(Clavell et al. 1996), and/or cytokine levels. (Gullestad et al. 1999)(Tsutamoto et al. …show more content…
The only approved in the last group is Aliskirin.
One of the major indications of RAAS inhibitors is blood pressure control. Despite all advances in medical sciences, 30.5% of men and 28.5% of women in the United States have hypertension.(Guo et al. 2012) The efficacy of ACEi and ARBs has shown to be similar to other first choice antihypertensive drugs, either as initial antihypertensive monotherapy or as a part of combination therapy of hypertension. In addition, there are a number of settings in which ACEi or ARBs are the antihypertensive drugs of choice because of possible benefits independent of blood pressure control.(Turnbull et al. 2008; Law, Morris, and Wald 2009) A comprehensive meta-analysis of 20 trials in RAAS inhibition proved that RAAS inhibition is associated with 5% decrease in all-cause mortality and 7% decrease in cardiovascular events in hypertensive patients(van Vark et al.
...ve stress [8] and can help combat many cardiovascular disorders, thus confirming the protective capabilities of nitric oxide. Another one of nitric oxide’s protective capabilities stems from its role as a potent vasodilator, and these vasodilation properties are primarily achieved through the activity of eNOS. eNOS is a membrane bound protein that is classified as a calcium-calmodulin dependent enzyme [13]. At resting concentrations of calcium, eNOS generates low amounts of nitric oxide, however, as intracellular calcium concentration increases, there is a potent enhancement of nitric oxide production by eNOS [13], which then goes on to cause vasodilation to prevent blockage of blood flow. Due to its generally low output, eNOS is largely associated with basal cardiac function, while iNOS is a much higher output enzyme, generating much more nitric oxide than eNOS [5].
(2013, July 8). Trauma Emergencies. Retrieved from https://ambulance.qld.gov.au/docs/09_cpg_trauma.pdf renin-angiotensin system. (2014). In Encyclopaedia Britannica.
Many compensatory mechanisms are stimulated in heart failure. These mechanisms involve rising ventricular preload, or the Frank-Starling mechanism, by ventricular dilatation and volume expansion, peripheral vasoconstriction to firstly sustains perfusion to significant organs, myocardial hypertrophy to protect wall strain as the heart expands, kidney sodium and water retention to improve ventricular preload, and start of the adrenergic nervous system, which elevates heart beat and contractile function. The activation of neurohormonal vasoconstrictor systems, which include RAAS, the adrenergic nervous system, and non-osmotic release of vasopressin will control these compensatory mechanisms (Henry & Abraham).
High Blood Pressure is anything that alters in peripheral vascular resistance, heart rate, or stroke volume that affects systematic arterial blood pressure. Long term effect of high blood pressure are serious and can cause heart attacks, strokes, kidney failure, and retinal damage. Hypertension is another medical word that substitutes the meaning of high blood pressure. It is known as the “silent killer” because it does not create any symptoms. The most common reason for high blood pressure is arteriosclerosis. Arteriosclerosis is the thickening and hardening of the walls of the arteries, occurring in old age. Four control systems have a job in maintaining blood pressure. These are the arterial baroreceptor and chemoreceptors’ system, regulation of body fluid volume, the renin- angiotensin system, and vascular autoregulation. Primary hypertension mostly occurs from a defect or malfunction in some or all of these
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.
The causes of hypertension are unknown. However; hypertension can be classified into two categories primary and secondary. Primary (essential) hypertension is increas...
Hypertension is a developing problem worldwide，associated with an increased risk of cardiovascular morbidity and mortality. In 2020, the world population will be approximately 7.8 billion people, and there will be 1 billon people who may be affected by hypertension (Tomson & Lip, 2005). One in three adults in the United States has high blood pressure. According to the report “Health, United States, 2010 with Special Feature on Death and Dying,” the prevalence of hypertension among adults 20 years old or older increased from 24% to 32% during 1988-1994 and 2005-2008. The African-American population has a higher prevalence of this health condition than white Americans do. In 2005 to 2008, the prevalence of hypertension among black males (41.4%) was more than 10%, compared to white males at 31.5% of the population. The hypertension rate of black females was more than twice that of white females. The death rate from hypertension among black males was 51.8 per 100,000, and among black females was 40.4 per 100,000; however, the morta...
" Journal of Clinical Hypertension 13.5 (2011): 351-56. EBSOHost.com - a. Web. The Web.
Today, cardiovascular disease is “the number one killer in the United States and the developed world” (Sapolsky, 2004, p. 41). Coronary heart disease (CHD) is the most common form of cardiovascular disease, and is responsible for claiming an unreasonable amount of lives every year. CHD can begin to accumulate in young adults, but is prominently found in both men and women in their later adult lives. As a result of CHD, men typically experience heart attacks, whereas women present with chest pains, known as angina (Matthews, 2005).
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...
WILLIAMS, P and POULTER NR et al (2004) Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society. British Hypertension Society, pp. 139-85
Renin is a type of protein enzyme secreted by the juxtaglomerular apparatus of the kidneys when the blood pressure is low in the arteriole. It is produced and stored as an inactive form which is known as prorenin in the juxtaglomerular cells (Hall, 2010). Anomalies in the renin-angiotensin-aldosterone system pathway such as overproduction of renin or excessive release of angiotensin II can lead to hypertension (Williams & Lemke, 2008). For instance, when the secretion of renin is abnormally high, a high amount of angiotensinogen (renin substrate) secreted by the liver will be converted to angiotensin I by renin. ...
Adrenopause, more commonly known as “man-opause”, is an aging- related hormonal shift due to a reduction in secretion of adrenal hormones. The adrenal glands are located on top of the kidneys and are primarily involved with the synthesis of corticosteroids including cortisol and catecholamines such ...
The pathophysiology of essential hypertension rests on the characteristic finding that there is an inappropriate increase in peripheral vascular resistance, as related to the cardiac output. Usually this occurs without without any cause being evident. This is possible due to the change in small arteries where the media/lumen ratio rises. Still it is not clear whether this is a cause or consequence of hypertension. The conduit of large arteries like the aorta becomes stiffer, also influences hypertension. Basically there have been no findings on the root cause of hypertension.
The kidneys are a bean-shaped organ in the human body and they have different functions and are of vital importance for it. The kidneys are the pair of organs, which are able to regulate the reabsorption of ions such as potassium, sodium and calcium, which are fundamental substances for the cell. Furthermore, they are involved in the reabsorption of nutrients in the bloodstream and they can regulate the acidity of the blood. Besides the regulation of the fluids and ions, the kidneys are also responsible for the regulation of many different hormones that are involved in homeostasis and metabolism. Because of their importance in the regulation of substances in the body, when the kidneys stop working properly all the body is influenced by that creating disequilibrium in the maintenance of homeostasi...