Feb
22
2009
Blood enters the kidney by the renal artery, a thick branch from the descending aorta. In the hilar, is divided into several branches which are distributed by the kidneys and the lobes are forming numerous branching afferent arterioles that form the glomerular ball. These are the walls of these capillaries that act as the Ultra Filters, allowing the passage of small particles. The blood that comes out through the efferent arteriole circulates through the blood vessels of the kidney (the real kidney capillaries that provide oxygen and the nutrients required for their function). These capillaries are grouped to form the renal vein, which in turn, poured into the inferior vena cava.
Given the role of the kidneys to eliminate waste products through urine, it is not surprising that these organs are receiving greater amounts of blood per gram of weight. One way to express the renal blood flow is to consider the renal fraction or fraction of cardiac output passing through the kidneys. For example, a subject of some 60 kg of weight, cardiac output is about 6 liters / minute, assuming 20% renal fraction (1.6 liters / min) of this volume. Dividing this volume by the weight of both kidneys, obtained a blood flow of 420 ml/min/100 g of tissue, flow substantially greater than the liver or muscle at rest.
The regulation of blood flow in the glomeruli is accomplished by three formations: the bearing polar cells of the macula densa and Goormaghtigh. The bearing consists of a polar wall thickening of the afferent arteriole before it enters the renal glomerulus. The arteriole loses its elastic membrane, the endothelium becomes discontinuio of the tunica media and is available in two layers, formed by secretory cells, these secretory cells produce erythropoietin and angiotensin. Goormaghtigh cells are arranged in the angle between the afferent arterioles and efectente and gather in small columns. Are highly related to the cells bearing polar. Between the two formations is the macula densa (macula densa or Zimmerman) that is in contact with the distal tubule and the afferent arteriole just before it enters the glomerulus. These three formations bearing polar cells of the macula densa and Goormaghtigh forming apparatus yuxtaglomerular. which is what regulates the flow of blood in the glomerulus.
Feb
21
2009
Whole glomerulus, renal capsule and tubular renal nephron is the functional unit of kidney. It is estimated that the human kidney contains about 1 million nephron. Most of the nephron is located in the cortical area and only the portion of the nephron consisting of the loop of Henle is located in the core. The nephron, but are essentially similar to each other, differ in length. The corpuscles have their shorter in more superficial layers of the cortex and the loops of Henle extend only up to half of the marrow. The nephron of these clusters are called cortical glomeruli. By contrast, long nephron begins with the heart and ears can reach almost reach the papilla. The nephron of these clusters are called glomeruli yuxtamedulares.
Glomerulus, the glomerulus (renal corpuscle or) consists of a capillary network lined by a layer of endothelial cells, a central region formed by mesangial cells, epithelial cells associated with a basement membrane forming the visceral layer, and finally a layer of parietal cells epithelial form the Bowman capsule. The glomerulus produces an ultrafiltered plasma when the blood and urinary space separated by a membrane filter composed of fenestrated glomerular peripheral basement membrane and visceral epithelial cells by a special, the podocitos. Between the two epithelial layers (parietal layer and visceral layer) extends a narrow cavity space called Bowman
Mesangial cells: cells are irregularly shaped, with a dense core and some elongated cytoplasmic extensions. It also contains large amounts of microfilaments made of actin, a-actinin and myosin, which give these cells many of the functional properties of smooth muscle cells. In addition to providing a structural support for the glomerular capillary loops, it is believed that mesangial cells are involved in the regulation of the leak. Vasoactive substances (angiotensin II, vasopressin, norepinephrine, etc..) Cause the accounts while they are relaxing by the PEG2, peptides and dopamine headphones.
Endothelial cells: the glomerular capillaries coated with a fine stab fenestrated endothelium. Endothelial cells show an extensive network of microtubules and filaments whose function is not well known. These cells synthesize nitric oxide (NO) and its surface are receptors for factor vascular endothelial growth (VEGF) is an important regulator of vascular permeability. Endothelial cells form the initial barrier to the passage of blood components from the light to the capillary space of Bowman
Visceral epithelial cells: also called podocitos are the highest in the glomerulus. They have long cytoplasmic extensions that extend from the main cell body and divides it into appendages called pedicels.
Feb
20
2009
The kidneys are lined by a fibrous capsule and consists of different types of structures: the cortical substance, immediately beneath the fibrous capsule and the medullary area. The cortical substance, dark red, surrounds the core substance that penetrates deeply into her training leading to a radio call pyramids medullary ray or Ferrein Ludwig.
The medullary substance, of lighter color, is comprised of 8-14 mass pyramid, Malpighian pyramids whose apex is opened in cavities in the form of glass called renal calyces converge in the ureter. Between the Malpighian pyramids are some extensions of the substance which are called cortical columns of Bertin.
The kidneys contain numerous microscopic tangles of blood capillaries, the glomeruli. Each receives blood from an afferent arteriole and efferent arteriole poured into another of smaller size. Both arterioles are contiguous and constitute a kind of stem vascular support. The glomerulus is surrounded by a double membrane, the Bowman capsule, which is replicated at the site where the afferent and efferent arterioles. On the opposite end, the membrane of the Bowman capsule by a thin continuous tube winding course, the renal tubule. The joint capsule of glomerulus and Bowman called Malpighian corpuscle.
The renal tubule emerging from the capsule of Bowman, called in its portion closest to the glomerulus proximal tubule, extends into a long winding tube (proximal tubule winding) which follows a U-shaped segment, the loop of Henle. Finally, the loop of Henle, is sinuous distal tubule that empties into a collecting tubule. The urine formed in the nephron is reflected in the collecting tubules, which represent the conduits that lead in the distal tubules winding. Collecting tubules are coming together with each other at different levels becoming higher caliber action that enters the spinal area. Ending in large ducts (Bellini ducts) that open directly into the renal calyces.