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An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. [1] Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primary site of vascular resistance. The greatest change in blood pressure and velocity of blood flow ...
The major determinant of vascular resistance is small arteriolar (known as resistance arterioles) tone. These vessels are from 450 μm down to 100 μm in diameter (as a comparison, the diameter of a capillary is about 5 to 10 μm). Another determinant of vascular resistance is the pre-capillary arterioles. These arterioles are less than 100 μm ...
Resistance arteries are usually small arteries or arterioles and include precapillary sphincters. [1] Having thick muscular walls and narrow lumen they contribute the most to the resistance to blood flow. Degree of the contraction of vascular smooth muscle in the wall of a resistance artery is directly connected to the size of the lumen.
The systemic circulation is a circuit loop that delivers oxygenated blood from the left heart to the rest of the body, and returns deoxygenated blood back to the right heart via large veins known as the venae cavae. The systemic circulation can also be defined as two parts – a macrocirculation and a microcirculation.
Metarterioles connect arterioles and capillaries. A tributary to the venules is known as a thoroughfare channel. [citation needed] The microcirculation has three major components: pre-capillary, capillary, and post-capillary. In the pre-capillary sector, arterioles, and precapillary sphincters participate. Their function is to regulate blood ...
Improper vasoconstriction may also play a role in secondary hypertension. [citation needed] To summarize, vasoconstriction is a physiological process that involves the narrowing of blood vessels, particularly arteries and arterioles, resulting in a reduction of blood flow to specific tissues or organs.
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Renin is produced by juxtaglomerular cells, also known as granular cells. 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