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The afferent arterioles are a group of blood vessels that supply the nephrons in many excretory systems. They play an important role in the regulation of blood pressure as a part of the tubuloglomerular feedback mechanism. The afferent arterioles branch from the renal artery, which supplies blood to the kidneys.
Juxtaglomerular cells (JG cells), also known as juxtaglomerular granular cells are cells in the kidney that synthesize, store, and secrete the enzyme renin. [1] They are specialized smooth muscle cells mainly in the walls of the afferent arterioles (and some in the efferent arterioles) [citation needed] that deliver blood to the glomerulus.
Extraglomerular mesangial cells are located in the junction between the afferent and efferent arterioles. These cells have a contractile property similar to vascular smooth muscles and thus play a role in “regulating GFR” by altering the vessel diameter. Renin is also found in these cells. [4]
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.
The afferent arterioles, then, enter Bowman's capsule and end in the glomerulus. From each glomerulus, the corresponding efferent arteriole arises and then exits the capsule near the point where the afferent arteriole enters. Distally, efferent arterioles branch out to form dense plexuses (i.e., capillary beds) around their adjacent renal tubules.
They resemble smooth muscle cells and play a role in renal autoregulation of blood flow to the kidney and regulation of systemic blood pressure through the renin–angiotensin system. Extraglomerular mesangial cells are part of the juxtaglomerular apparatus , along with the macula densa cells of the distal convoluted tubule and the ...
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 ...
Intrinsic ocular muscles [1] or intraocular muscles [2] are muscles of the inside of the eye structure. The intraocular muscles are responsible for the protraction and retraction of the eyelids and reaction to light and pupil accommodation. [2] They're different to the extraocular muscles that are outside of the eye and control the external ...