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When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium or chloride ion concentration, the macula densa of the distal tubule releases prostaglandins (mainly PGI2 and PGE2) and nitric oxide, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure ...
In the kidneys, angiotensin II constricts glomerular arterioles, having a greater effect on efferent arterioles than afferent. As with most other capillary beds in the body, the constriction of afferent arterioles increases the arteriolar resistance, raising systemic arterial blood pressure and decreasing the blood flow. However, the kidneys ...
The muscle tension in the afferent arteriole is modified based on the difference between the sensed concentration and a target concentration. [5] Vasodilation of the afferent arteriole, which results in increased glomerular filtration pressure and tubular fluid flow, occurs when MD cells detect a chloride concentration that is below a target value.
These cells are similar to epithelium and are located in the tunica media of the afferent arterioles as they enter the glomeruli. [4] The juxtaglomerular cells secrete renin in response to: Stimulation of the beta-1 adrenergic receptor; Decrease in renal perfusion pressure (detected directly by the juxtaglomerular cells)
In the kidney, the macula densa is an area of closely packed specialized cells lining the wall of the distal tubule where it touches the glomerulus.Specifically, the macula densa is found in the terminal portion of the distal straight tubule (thick ascending limb of the loop of Henle), after which the distal convoluted tubule begins.
Renin (etymology and pronunciation), also known as an angiotensinogenase, is an aspartic protease protein and enzyme secreted by the kidneys that participates in the body's renin-angiotensin-aldosterone system (RAAS)—also known as the renin-angiotensin-aldosterone axis—that increases the volume of extracellular fluid (blood plasma, lymph, and interstitial fluid) and causes arterial ...
Increases in systemic blood pressure will maintain renal perfusion pressure; however, constriction of the afferent and efferent glomerular arterioles will tend to restrict renal blood flow. The effect on the efferent arteriolar resistance is, however, markedly greater, in part due to its smaller basal diameter; this tends to increase glomerular ...
This makes adenosine a useful medication for treating and diagnosing tachyarrhythmias, or excessively fast heart rates. This effect on the A 1 receptor also explains why there is a brief moment of cardiac standstill when adenosine is administered as a rapid IV push during cardiac resuscitation. The rapid infusion causes a momentary myocardial ...