Vessels and nerves of the kidney

The circulatory bed of the kidney is represented by arterial and venous vessels and capillaries, through which within a day there are from 1500 to 1800 liters of blood. Blood enters the kidney along the renal artery (branch of the abdominal part of the aorta), which is divided into the anterior and posterior branches in the kidney gates. There are additional arteries of the kidney, which enter the portal of the kidney or penetrate the kidney through its surface. In the renal sinus, the anterior and posterior branches of the renal artery pass in front and behind the renal pelvis and divide into segmental arteries. The anterior branch delivers four segmental arteries: to the upper, upper anterior, lower anterior and lower segments. The posterior branch of the renal artery continues into the posterior segment of the organ called the posterior segmental artery. Segmental arteries of the kidney branch into inter-lobar arteries that run between the neighboring renal pyramids in the renal columns. At the border of the brain and cortex, the interlobar arteries branch and form arched arteries located above the bases of the renal pyramids, between the cortical and medulla of the kidney. From the arc arteries, numerous interlobular arteries leave the cortex, giving rise to the glomerular arterioles. Each bringing a glomerular arteriolus (bringing a vessel); (arteriola glomerularis afferens, s.vas afferens) breaks up into capillaries, the loops of which form a globule (glomerulus), a globule capillary network (rete capillare glomerulare). From the glomerulus leaves the glomerular arteriolus, or the carrying vessel (arteriola glomerularis efferens, s.vas efferens), its diameter is smaller than the diameter of the bringing glomerular arterioles. Coming out of the glomerulus, the glomerular arteriolus dissolves into capillaries that span the renal tubules (nephrons), forming a capillary network of the cortical and medullary substance of the kidney. Such branching of the arterial vessel bringing the glomerulus to the capillaries and the formation of the vascular arterial vessel from the capillaries was called the miraculous network (rete mirabili). In the medulla of the kidney, from the arcuate and interlobar arteries and from some outgoing glomerular arterioles, direct arterioles depart, which break down into capillaries, blood supplying the kidney pyramids.

Carrying out arterioles further form a peritubular juxtamidullary capillary network.

Peritubular capillary network. In the middle and surface areas of the cortex, the outgoing glomerular arterioles form the peritubular capillaries, which, enveloping the proximal and distal renal tubules, supply them with blood. Capillaries of cortical substance open into radially located interlobular veins, which subsequently flow into the arc veins (vv. Arcuatae), and those in turn - into the renal and inferior vena cava.

Yukstamedullary capillary network. In the juxtamendullary zone, each glomerular arteriolus exits towards the brain substance of the kidney, where it breaks up into bundles of direct arterioles (arteriolae rectae). Each bundle consists of approximately 30 descending vessels, while those that are located on the periphery of the beam branch into the capillary network in the outer zone of the medulla. The central part of the beam of direct arterioles, consisting of descending and ascending vessels, penetrates deep into the area of the brain substance. These vessels repeat the course of the knees of the loop of Henle. Closer to the renal papilla, the vessels change their direction to the opposite. They break down into several branches and in the form of straight venules (venulae rectae) permeate the brain substance of the kidney. The venules flow into the arc veins (vv. Arcuatae), which then pass into the interlobar veins (vv. Interlobares) and, falling into the renal vein, the kidneys leave the renal gates.

Blood supply to the kidney is significant (the magnitude of renal blood flow is 1000-1200 ml / min - 20-25% of the cardiac output) and exceeds the blood supply of all other organs. Blood supply to the kidneys is uneven: 80-85% of the total renal blood flow accounts for the cortical substance, and less than 10% for the kidney's medullary substance; nevertheless, it is believed that in the quantitative sense, the medullary blood flow is approximately 15 times higher than the flow of the resting muscle and is equal to blood flow through the brain.

From the capillary network of the cortical substance of the kidney, venules are formed ; merging, they form interlobular veins, flowing into arched veins, located on the border of cortical and brain matter. Venous vessels of the medulla of the kidney also flow here. In the most superficial layers of the cortical substance of the kidney and in the fibrous capsule, the so-called stellate venules form which merge into the arched veins. They, in turn, pass into the interlobar veins, which enter the renal sinus, merge with each other into larger veins forming the renal vein. The renal vein emerges from the portal of the kidney and flows into the lower vena cava.

Lymphatic vessels of the kidney accompany the blood vessels, along with them go out of the kidney through its gates and flow into the lumbar lymph nodes.

The nerves of the kidneys depart from the celiac plexus, the nodes of the sympathetic trunk (sympathetic fibers) and from the vagus nerves (parasympathetic fibers). A renal plexus is formed around the renal arteries, which gives the fibers to the kidney substance. Afferent innervation is carried out from the lower thoracic and upper lumbar spinal nodes.