Kidney (ren)

The kidneys are located nabroshena by the sides of the spine at the level of the DII-L2. The right kidney one's pressing away slightly down by the liver and is slightly lower than the left (Fig. 1). The length of the normal kidney 9-12 cm, width 4,5-6,5 cm, thickness 2.3 cm, weight 110-140,

topography of kidneys and ureters
Fig. 1. Topography of kidneys and ureters.

The kidney is surrounded by a fat capsule and with it is located in the fascial sheath formed by pre - and posudomoechnaja bands and funnel narrowed from top to bottom, which somewhat limits the mobility of the kidneys. The renal parenchyma covered with a thin fibrous capsule, forming two layers: the outer, consisting of several dense records and network elastic fibers, and internal containing smooth muscle fibers and histiocytes. Between the outer and inner layer is loose cellulose. Through the lymphatic vessels renal capsule can spread bacteria, toxins, cancer cells. The outer layer can be removed (decapsulate kidney), internal remains fixed to the cortical layer of the kidneys. Fibrous capsule comes to the gates of the kidneys, where it meets adventitia renal pelvis and blood vessels. The functional unit of the kidney is the nephron. Each kidney has more than 1 million nephrons. Nephron consists of a ball and related isolated system tubules.
The glomerulus is a network not connected capillaries located in the cavity capsules Shumlyanskiy - Bowman. The wall of the capsule consists of two pieces: the visceral and parietal lined single flat epithelium, between which forms a cavity capsules, passing directly into the cavity canaliculi. Close up tubule repeatedly bent. This period is called the proximal segment, or tortuous canaliculus of the first order; his wall consists of one layer cubic epithelium. Second, thin, segment represents the descending branch Genle hinges; he lined squamous epithelium. Third, the distal segment is formed of the ascending branch of the Genle hinges, which goes back into the cortical layer and passes in a straight tubule of the second order. Straight tubule second order flows into the collective tube, which is the final segment of the nephron. Collective tube point holes appear on the papilla of the pyramid (Fig. 2).

Fig. 2. The scheme of the nephron.
1 - the glomerulus; 2 - straight tubule of the first order; 3 - straight tubule of the second order; 4 - the descending part of Genle hinges; 5 - ascending portion of the loop; b - bend downward part of a loop in ascending; 7 - the collective tube.

The renal parenchyma consists of two layers: an outer cortex adjacent to the fibrous capsule, and internal brain, adjacent to the cups and the pelvis. In the cortical layer are the glomeruli and convoluted tubules of both the first and the second order, and the Central segments collectively tubes. In cerebral layer are descending and ascending knee loops of Henle and peripheral departments collectively tubes. The last together with loops gentle form 10-15 pyramids wedge-shaped. Its broad grounds pyramid adjacent to the cortical layer, and on the tops of them (the papillae, or sobachko) point holes open mouth collective tubes. Papillae into small cups (calices minores). Cortical layer situated between the pyramids narrow strips, the so-called bartenieva columns (Fig. 3).

sectional cut kidney
Fig. 3. Sectional cut the kidneys.

A small Cup, or a Cup of second order, surrounds papilla cuff dome-shaped form, which forms an arch Cup (fornix calicis). According to the number of papillae the number of small cups in the range of 10-15.

shallow Cup during diastole and systole
Fig. 4. Shallow Cup during diastole and systole (by A. Ya. to Pytel). a and b - diastolic phase, the accumulation of urine in a Cup: vig - phase systolic, emptying the Cup.

Muscular wall of a Cup formed a thin layer of smooth muscle with a spiral direction. Successive contraction (systole) and relaxation (diastole) wall Cup create in the cavity its alternating the vacuum state and spadenia walls (Fig. 4). This facilitates the flow of urine from the collecting tubes in a Cup, promotion of small cups at large and, further, in the renal pelvis and, to some extent protects the code Cup from gaps in pathological pressure increase in urine diversion routes (for example, if the obstruction of the ureter stones, delays urine and so on).
Small cups fall into 2-3 large bowl, which in turn opened into one large cavity - the renal pelvis, funnel turning into the ureter. Over the last urine in the bladder. The capacity of the pelvis 5-8 ml of the Wall of the pelvis consists of an inner and outer longitudinal circular layers of smooth muscles. Inside the sack, like a Cup, lined with transitional cubic epithelium.
Periodic reduction of the pelvis and ureter contribute to the promotion of urine from the kidney to the bladder.
There are vnutripechenochny and vnepochechny type pelvis.
When you first pelvis is located entirely within the kidneys, in the second it is fully or partially located outside it.
Renal artery, falling into the kidney, is divided into two, rarely three branches that pass between the pyramids, - majdalawi artery. The latter form of the arc passing between the brain and the cortical layer (AA. arcuatae),OT which depart magdalsophia artery divisible by vasa afferentia - leading vessels of the glomeruli. The capillaries of up together in the blood vessels carrying blood to and from the ball (vasa efferentia). Diameter of outlet of the vessel twice less than the diameter of the lead, which helps slow the flow of the blood into the fetal position, increased pressure in it and filtering primary urine (see Fig. 2).
On leaving the clew passing vessel again splits into the capillaries that surround the network corresponding to the ball straight tubule and then passing in venous capillaries.
Unlike the kidney arteries that form between a small number of anastomoses, renal vein widely anastomose with each other. They merge into two main veins - for the upper and lower half of the kidneys, and then combined into a single trunk, which flow into the inferior Vena cava.
Anterior branch renal artery supplies the ventral and the rear branch - dorsal half of the kidneys, between which is formed malacologica area that should be considered in the sections of the kidney. Renal artery and renal vein lie above the pelvis, and Vienna is in front of the arteries.
10% of people meet anomaline (incremental) vessels originating from renal artery or aorta and flowing into the kidney at the poles or in other places. Damage unnoticed extension of blood vessels in the kidney surgery can cause serious bleeding.
In the zone of the cortical layer, bordering the brain (juxtamedullary area), vasa efferentia glomeruli have a wide diameter, so that the blood flow in the glomeruli are not slowing down. Filtration capacity of glomeruli this zone is negligible. In addition juxtamedullary area, as in cerebral layer, there are many arterio-venous anastomoses, through which blood circulates, bypassing the glomeruli (Fig. 5). In norm on these anastomoses and glomeruli juxtamedullary zone passes only 10-15% of blood that flows through the kidneys.


the blood supply to the kidney
Fig. 5. The blood supply to the kidney.

The lymphatic vessels of the kidneys accompany the blood vessels, forming at the gate kidney plexus, surrounding the renal artery and vein. In the fibrous capsule and the pelvis lymph vessels little, kidney parenchyma, on the contrary, is very rich in them.
Innervation of kidneys at the expense of the sympathetic and parasympathetic nervous system. Sympathetic fibers are composed of big and small splanchnic nerves, as well as from individual ganglia edge of sympathetic trunk. Parasympathetic nerves kidney away from the trunk of the vagus
nerve.
Urine out of the body all of the nitrogen and part of the nitrogen-free products of metabolism, the most part of inorganic salts, released from the body, about 60-70% of the total produced by the body of water, as well as many drugs. The kidneys regulate the consistency of blood composition, acid-base balance and blood pressure.
Released in tubules of glomerular filtrate, the so-called primary urine, identical to human blood plasma, devoid of proteins.
The purpose tubules is, first, in the electoral reabsorption, i.e. the absorption of primary urine in the blood of some substances, secondly, tubular secretion, i.e. the allocation of blood into the lumen of the tubules some parts of urine.
Regulates the activity of the kidneys antidiuretic hormone posterior lobe of the pituitary. The latter provides one of the major functions of the kidneys is to save water body.
Some reflex (pain), circulatory (sharp drop in blood pressure in the shock or profuse bleeding) and toxic (sepsis, hemolysis, burns, crush of tissue) of exposure cause irritation renal vasomotion, resulting in vasospasm cortical layer and vasodilatation juxtamedullary zone and cerebral layer, which directs the bulk of blood flowing in the kidneys. Filtering urine sharply reduces or stops completely. It depends on what the blood bypasses the glomeruli of the cortical layer or through the glomeruli with low filtration ability, and besides, spasm of cortical vessels leads to a cerebral cortical layer that causes the degeneration and necrosis of epithelial tubules, especially cylindrical epithelium of the distal them, i.e. tubules of the second order, highly sensitive to oxygen starvation (principally the distal nephron). Necrosis of epithelial leads to the porosity of the walls of the tubules of the cortical layer; if in them and gets a certain amount of urine, it probative in the adjacent bone interstitial tissue of the cortical layer, causing swelling; kidney increases in volume, fibrous capsule is strained by affecting the kidney parenchyma ("glaucoma" kidney). To spasm of blood vessels joins mechanical squeeze them. Removing the fibrous capsule (decapsulate) can eliminate swelling of the kidneys, helping to restore normal blood flow.