Notes

6 functions of kidneys: regulate water/electrolyte imbalance, regulation of arterial pressure, regulation of EPO prod., regulation of Vit. D prod., metabolic excretion, and gluconeogenesis
Urinary system: kidneys, ureters, bladder, urethra
Hilum penetrated by: renal artery, renal vein, renal vein, lymphatics, renal nerve
Renal Internal Structure: Cortex (contain glomeruli) on outside, medulla (contain renal tubules), renal pelvis (composed of minor calyxes that flow into major calyxes)
Arterial flow: Renal artery --> segmental arteries --> interlobar arteries --> acruate arteries --> interlobular arteries --> afferent arteriole --> Glomerulus
Nephron components: proximal convoluted tubule --> descending loop --> ascending loop --> distal convoluted tubule --> collecting duct
Cortical nephrons vs juxtamedullar nephrons: Cortical nephrons have short loops of Henle and the efferent arteriole flows into the peritubular capillary network. They are responsible for reabsorption. Juxtamedullar have long loops of Henle that extend into the medulla, where the efferent arterioles follow. They are responsible for the formation of urine.

Urine flows from collecting ducts in the nephron to the renal pelvis into the ureters where it travels down to the bladder. Urine is propelled through peristalsis that is generated from electrical pacemakers in the proximal region of the renal pelvis. Stretching activates these pacemakers.
Urothelium lines the renal pelvis, ureters, and bladder. Outermost layers is Advenita that contains blood vessels, nerves, and lymphatics. Then follows the muscular region: outer circular and inner longitudinal layer. Lamina Propria is a layer of loose connective tissue. Innermost layer is the Lumen which is lined by transitional epithelium. Transitional epithelium is 5-6 layers, base layers are cuboidal, intermediate layers are columnar and surface layer is polyhedral. This allows for retention of urine.
Ureterovesical junction is where ureters enter the bladder. The bladder has two parts: fundus and bladder neck. Ureters enter bladder obliquiely and close when pressure rises, preventing reflux.
Bladder filling/voiding: While voiding, urothelium is relaxed, 5-6 cell layers thick, with a folded mucosal membrane. While filling, the urothelium is stretched causing the mucosal membrane to unfold and become only 1-2 cell layers thick.
On the surface of the epithelium, umbrella cells are held together by tight junctions. They are distinguished by hinges and plaques (depressions lined with uroplakin)
Filling stimulates exocytosis and endocytosis of cells, but the net rate of exocytosis is higher so that surface area increases.

4 layers of abdominal muscle: external oblique --> internal oblique --> rectus abdominus --> transverse abdominus
Greater pelvis (between ilium, above pelvic inlet) and Lesser pelvis (from pelvic inlet to pelvic outlet)
Pelvic cavity divided between oblique floor of pelvic inlet (superior) and lower floor (pelvic floor)