Urinary

• The urinary system consists of the kidneys, ureters, bladder, and urethra.
• The kidneys are responsible for filtering blood, producing urine, and regulating blood pressure.
• The ureters are responsible for transporting urine from the kidneys to the bladder.
• The bladder is responsible for storing urine.
• The urethra is responsible for the expulsion of urine from the body.
• The renal hilum is a medial indentation where several structures enter or exit the kidney (ureters, renal blood vessels, and nerves).
• Conversion of vitamin D to its active form
• The kidneys are situated against the dorsal body wall in a retroperitoneal position (behind the parietal peritoneum)
• Production of erythropoietin to stimulate red blood cell production
• The right kidney is slightly lower than the left (because of position of the liver)
• The kidneys are located at the level of the T12 to L3 vertebrae.
• An adult kidney is about 12 cm (5 in) long and 6 cm (2.5 in) wide
• Renal corpuscle consists of glomerulus, a knot of capillaries made of podocytes, and glomerular (Bowman’s) capsule, a cup-shaped structure that surrounds the glomerulus.
• Glomerular (Bowman’s) capsule is the first part of the renal tubule.
• Cortical radiate veins return blood to the interlobar veins, which in turn return blood to the renal vein.
• From the glomerular (Bowman’s) capsule, the subdivisions of the renal tubule are: proximal convoluted tubule (PCT), nephron loop (loop of Henle), and distal convoluted tubule (DCT).
• Each nephron consists of two main structures: renal corpuscle and renal tubule.
• Each kidney contains over a million nephrons, which are the structural and functional units of the kidneys.
• One-quarter of the total blood supply of the body passes through the kidneys each minute.
• Filtration slits create a porous membrane ideal for filtration.
• Renal artery provides each kidney with arterial blood supply.
• Podocytes make up the inner (visceral) layer of the glomerular capsule.
• Renal artery divides into segmental arteries, interlobar arteries, and arcuate arteries.
• Renal tubule extends from glomerular capsule and ends when it empties into the collecting duct.
• Proteins and blood cells are normally too large to pass through the filtration membrane.
• Urine formation is the result of three processes: Glomerular filtration, Tubular reabsorption, and Tubular secretion.
• Each nephron is associated with two capillary beds: the glomerulus and the peritubular capillary bed.
• If arterial blood pressure is too low, filtrate formation stops because glomerular pressure will be too low to form filtrate.
• Podocytes cling to the glomerular capillaries.
• Juxtamedullary nephrons are found at the cortex-medulla junction and their nephron loop dips deep into the medulla.
• The glomerulus is fed and drained by arteries.
• The peritubular capillary beds arise from the efferent arteriole of the glomerulus and are low-pressure, porous capillaries adapted for absorption instead of filtration.
• The capacity of the urinary bladder is about 5 inches long and holds about 500 ml of urine, capable of holding twice that amount of urine.
• Most reabsorption occurs in the proximal convoluted tubule.
• Glomerular filtration is a nonselective passive process where water and solutes smaller than proteins are forced through glomerular capillary walls.
• Cortical nephrons are located entirely in the cortex and include most nephrons.
• The peritubular capillaries cling close to the renal tubule to receive solutes and water from tubule cells and drain into the interlobar veins.
• Filtrate will be formed as long as systemic blood pressure is normal.
• The efferent arteriole receives blood that has passed through the glomerulus.
• Tubular reabsorption is the process where the peritubular capillaries reabsorb useful substances from the renal tubule cells, such as water, glucose, amino acids, ions, and some reabsorption is passive; most is active (ATP).