module7_a&p2_urinarysystem.docx - Urinary System Composed...

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Urinary System Composed of: o A pair of kidneys o 2 ureters Drain from the corresponding kidney into the bladder. o 1 urinary bladder o 1 urethra Carries wastes and homeostasis of blood volume and chemical composition. Kidney Anatomy Bean shaped, about the size of a can of soup and weighs ~5 oz (adult). RT kidney is slightly lower than the LT because of liver location above it. Both are protected by the rib cage because of their location between T12 and L3 vertebrae. Medial surface is concave and has a cleft called the renal hilus. Renal hilus leads to the renal sinus. Ureters, blood vessels, and nerves are in the sinus and enter the kidney at the hilus. Adrenal gland is above each kidney. The surface is protected by 3 layers of specialized tissue: o Inner layer: Renal Capsule Tough, fibrous outer skin of the kidney that protects it from injury and infection. o Adipose Capsule Outside of the renal capsule, a fatty layer that protects against trauma. o Renal Fascia Outer layer; dense, fibrous connective tissue that keeps the kidney in place inside the abdominal cavity. Three distinct regions of the kidney: o Cortex Glomerular capsule located here; distal and proximal convoluted tubule sections of the nephrons along with associated blood vessels also located here. o Medulla Is divided into sections called pyramids. The pyramids point toward the center of the kidney. Loop of Henle is located here. Collecting duct sections of the nephrons along with associated blood vessels also located here. o Pelvis Centermost section of the kidney; near the renal hilus; constitutes a funnel- shaped tube that connects to the ureter as it leaves the hilus. Several extensions of the pelvis (calyces) collect urine, which drains continuously into the renal pelvis and subsequently into the ureter. The ureter transports the urine to the bladder to be stored. The outer renal cortex (just inside the renal capsule) is a continuous outer region with several projections (cortical columns) that extend down between the renal medulla pyramids.
Kidney Blood and Nerve Supply Kidneys are innervated by many blood vessels so that they can filter the blood to regulate its composition with the renal arteries. The blood vessels deliver about 1200mL of blood per minute directly from the abdominal aorta which amounts to 20% of the cardiac output. Renal arteries branch into 5 segmental arteries that divide further into lobar arteries, then further into interlobar arteries, which pass between the renal pyramids. Interlobar arteries then divide into the arcuate arteries, which branch into several interlobular arteries that feed into the afferent arterioles that supply the glomeruli. After filtration occurs, the blood moves into the efferent arterioles and either the peritubular or vasa recta capillaries and then drains into interlobular veins, which converge into arcuate veins, then interlobar veins. Then to the renal vein, which exits the kidney.

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