Lecture 8.3 URINARY SYSTEM (Chapter 24) Function: removal of metabolic waste materials (mostly urea)Urea: metabolic waste material formed from the digestion of proteinsProtein digestion releases ammonia which is detoxified in the liveby attaching a CO2 molecule producing urea.Urinary SystemNutrientsdigestive systembloodliver (urea production)bloodurinary systemexcretionKidneys Functionso Removal of waste from blood (urine formation)o Regulate body water volume Diluted urine (removal of excess water) Concentrated urine (conservation of water) Location o Retroperitonealo Level of T12-L3 vertebrae Capsule o Fibrous capsule: outer layer of kidney, maintains shape Hilum o Where the renal artery, renal vein, and ureter leave the kidneyInternal Cortex o Renal cortex Contains millions of nephronsMedulla and renal pyramids o Renal medulla Pyramids - Collect urine from tubules Papilla: tip of the pyramid that points inward Renal columns: separate adjacent pyramids Renal lobe: single renal pyramid plus the cortical tissue that surrounds that pyramid Renal sinus o Filled space that contains the renal vessels and nerves, some fat and urine carrying tubes called renal pelvis and calices Renal pelvis: expanded part of the uretero Major and minor calyces: branches superior from the renal pelvis from the ureter, collect urine draining from the papillae and empty it into the renal pelvis and into the ureter to the bladder Minor: encloses the papillae of the pyramids, at the tip of pyramids Major: each divide to form several minor calyxNephron: each contain about the corpuscle, tubule Renal corpuscle: only in the cortex o Glomerulus (efferent and afferent arterioles) Supplied by the Afferent arterioleenters and drained by theefferent arteriorle o Glomerular (Bowman’s) capsule Filtration membraneo Capsular space is usually urine o Efferent arteriole (exits) Renal tubule is divided into the: o Proximal convoluted tubule o Nephron loop (Loop of Henle) o Distal convoluted tubule o Collecting tubule Peritubular capillaries: surround the tubules Ureters o Slender tube Connects renal pelvis to bladder Approx. 25 cm (12 inches) long Approx 3 mm in diameter Where you get kidney stones, they are so painful because the diameter is smallBladder and micturitiono Stores urineo Expels urine (detrusor muscle layer)o Bladder is larger in males than in femaleso Detrusor muscle: muscle that surrounds and makes up part of the bladdero Trigone: white triangle thing o Ureteric openings Internal urethral sphinctero Urinationo Micturation reflex Initiated by stretching of bladder Detrusor muscle contraction Internal sphincter relaxation (involuntary) External sphincter relaxation (voluntary)Urethrao Tube from bladder to external excretion openingo Longer in males than in femaleso Internal sphinctero Smooth muscle that keeps urethra closed o External sphinctero Skeletal muscleo External urethral orificeBlood vessels (figure 24.4b) o Arteries (Left and Right):o AortaRenalSegmentalInterlobarArcuateCortical radiate (interlobular)Afferent arterioleGlomerulusàEfferent arterioleàPeritubular capillaries and vasa rectao Veins (Left and Right): o Vasa rectaàInterlobular (cortical radiate)àArcuateInterlobarRenalàIVCRenal
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