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The glomerulus (pl.: glomeruli) is a network of small blood vessels (capillaries) known as a tuft, located at the beginning of a nephron in the kidney. Each of the two kidneys contains about one million nephrons. The tuft is structurally supported by the mesangium (the space between the blood vessels), composed of intraglomerular mesangial cells.
The renal corpuscle is composed of two structures, the glomerulus and the Bowman's capsule. [3] The glomerulus is a small tuft of capillaries containing two cell types. Endothelial cells, which have large fenestrae, are not covered by diaphragms. Mesangial cells are modified smooth muscle cells that lie between the capillaries.
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 ...
Homeometric autoregulation, in the context of the circulatory system, is the heart's ability to increase contractility and restore stroke volume when afterload increases. [6] Homeometric autoregulation occurs independently of cardiomyocyte fiber length, via the Bowditch and/or Anrep effects.
In zoology, the trilobite Fenestraspis possessed extensive fenestrae in the posterior part of the body. [8] In the Paleognathae, there is an ilio–ischiatic fenestra. Fenestrae are also used to distinguish the three types of amniote: The ancestor of the amniotes is a primitive lizard, Hylonomus. From this reptile, three groups of amniotes ...
Each nephron begins in a renal corpuscle, which is composed of a glomerulus enclosed in a Bowman's capsule. Cells, proteins, and other large molecules are filtered out of the glomerulus by a process of ultrafiltration , leaving an ultrafiltrate that resembles plasma (except that the ultrafiltrate has negligible plasma proteins ) to enter Bowman ...
The table below shows the path that blood takes when it travels through the glomerulus, traveling "down" the arteries and "up" the veins. However, this model is greatly simplified for clarity and symmetry. Some of the other paths and complications are described at the bottom of the table.
The heart is the driver of the circulatory system, pumping blood through rhythmic contraction and relaxation. The rate of blood flow out of the heart (often expressed in L/min) is known as the cardiac output (CO). Blood being pumped out of the heart first enters the aorta, the largest artery of the body.