Urinary Anatomy.docx

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Anatomy and Cell Biology
Anatomy and Cell Biology 3319
Kem Rogers

Urinary Anatomy • Functions o Filters blood – filters 200 L of fluid/day  Rich blood supply  Will push fluid out of blood, into the kidney  Fluid then passes through tubules and will be reabsorbed or will be excreted o Excretes approximately 1.4 L/day  Eliminates waste – nitrogenous compounds  Excrete excess ions – water/electrolyte balance  Produce, transport & store urine - micturition (process of urination) o Blood pressure regulation • Posterior Abdominal Wall Region o Middle picture  See posterior abdominal wall covered by peritoneum  Visceral layer attached to organs and parietal attached to wall o Left Picture  Retroperitoneal  Behind the peritoneal layer o Ureter comes off each kidney and descend into pelvic cavity  Joins with bladder which is deep within the pelvis o Adrenal glands on top of each kidney Kidneys • Bean-shaped • Lies in superior lumbar region – extend from level of 11 or 12 thoracic vertebra to 3 lumbar vertebra • Convex outer lateral surface • Concave medial surface = hilum – where structures will enter and exit (arteries, veins & ureter) • Kidneys have a superior pole and inferior pole • Right kidney is crowded by the liver and therefore lies slightly inferior to the left kidney • Upper portions are somewhat supported by ribs (superior pole) • Lower portions are not protected by the ribs o Vulnerable organs because no bony structure o Have muscles on the back (posterior abdominal wall muscles) to somewhat protect the kidneys • Anterior view o Kidneys located behind peritoneal layer (thin membrane) o Right side: liver pushes right kidney down – closely associated to superior pole of right kidney o Inferior vena cava - right to midline o Duodenum – sits on top of the right kidney & will loop around and come into close contact with left kidney as we come to the ileum o Blood supply:  Supplies the small intestine (superior mesenteric artery & vein) will pass very close to SI  Renal arteries are located close by  If an ulcer or problem with intestine – impact blood supply to intestines or kidneys o Pancreas  Spans across left kidney and comes into a little contact with right kidney  If enzymes get released into the area – digests structures around it • Horizontal section o Posterior protection: vertebra o In front of peritoneum: intestines o Several layers of connective tissue surround each kidney  Fibrous capsule • Thin, tough connective tissue • Adheres directly to kidney surface • Maintains shape and forming a barrier that can inhibit the spread of infection  Perirenal fat capsule (perinephric) • External to renal fibrous capsule • Cushion kidney’s against blows and help hold kidneys in place • Preserved (last places to lose weight)  Renal fascia (paranephric or pararenal fat) • External to fat capsule • Contains external layer of fat • Dense irregular connective tissue • Anchors kidney & adrenals in abdomen • Easier to go through the postero-lateral side if you want to perform surgery Blood Supply • Abdominal aorta branches into o Celiac trunk  stomach, liver & pancreas o Superior mesenteric artery  small intestine o Left & right renal arteries  horizontal  Right renal artery • Slightly longer than the left • Because aorta slightly off midline - right renal supply has to travel a bit further o Gonadal artery  Testicular artery – males & ovarian artery – females  Gonads start origins close to the kidney - close proximity for blood supply  Testes and ovaries descend into pelvis and drag blood supply with it • Venous drainage of renal arteries o Drains into inferior vena cava o Venous drainage of the left kidney is slightly longer – inferior vena cava is off the midline • Venous drainage of gonadal arteries o Right side will go to IVC o Left will drain back into the left renal vein o Differences due to geometry of structures - left is a little longer = more space for vein to attach o Lymphatic drainage of gonads follows venous drainage o Tumors from reproductive tumors, will end up in abdominal region due to venous drainage • Ulcer in duodenum will erode the superior mesenteric or drainage of kidney or arterial supply of kidney • Superior mesenteric artery blockage  constrict renal venous drainage (especially of the left kidney) Anatomy • Hilum: renal artery, vein & nerves enter/exit • Outer cortex layer: pale, granular o Filtrate begins here • Some of cortex will come down in between areas of medulla renal columns – separate pyramids • Inner medulla layer: contains cone-shaped masses: pyramids, broad base abuts cortex o Renal pyramids have striations because they contain roughly parallel bundles of urine collecting tubules o Renal pelvis will funnel filtrate toward ureter Blood Supply & Splits • Renal artery o Segmental artery  Lobar artery (through renal column) • Interlobular artery o Nephron (working unit of kidney – filtration & reabsorption) • Nephron o Interlobular veins  Interlobar veins • Renal veins o Inferior vena cava Nephron (Uriniferous Tubule) • One million per kidney • Thousands of collecting ducts – multiple nephrons converge • Renal corpuscle o Capillary filtration • Fluid leaving tubule is urine • Interlobular arteries – have smaller branches that make up the vascular renal corpuscle • Afferent artery coming in  capillaries (fluid gets forced out of capillaries)  leaves via efferent artery • Renal corpuscle o Glomerulus (capillary tuft) o Bowman’s capsule (cup that collects filtrate) • Tubule o Proximal convoluted tubule o Ascending loop of henle o Descending loop of henle o Distal convoluted tubule o Collecting duct • Through tubules – water & ions are reabsorbed Renal Corpuscle • Glomerulus = capillary tuft o Will fan out into many branches o Have afferent arteriole coming in and then leaves via efferent o Efferent arteriole has a small diameter  Creates high pressure within tuft  Blood has to go through smaller opening to get out of tuft • Bowman’s Capsule o Cup that will collect everything filtered out of the kidneys o Parietal layer on the outside o Visceral layer of cells attached to capillary – filtration  Podocytes • Covers the capillary • Filtration slits – allows filtrate to pass through  Capillary fenestration • Allow material to leave the capillary • Not big enough in the kidney to let whole cells leave (RBC/WBC) • Large proteins cannot leave • Fluids can be filtered • If you do a urine test and find RBC or protein in the liver – then something is wrong with the filtration apparatus Processes & Organization Nephron Types • Cortical nephrons o 85% o Almost entirely in cortex – only slightly dips into medulla o Peritubular capillaries from efferent arterioles • Juxtamedullary nephrons o At cortex-medulla interface o Loops invade deep into medulla o Descending limp more extensive o Vasa recta capillaries – helps draw out more fluid to form more concentrated urine Clinical Correlate: Polycystic Kidney Disease • Autosomal dominant trait • Instead of kidneys being smooth, there are few or multiple, fluid filled holes in the kidney: cysts • Most of the cortex and medulla is taken up by large cysts • Important cause of renal failure • Individuals would require dialysis (need to have blood filtered mechanically outside of the body) • Kidney is much larger than it would be normally - cysts taking up functional kidney tissue Urine Formation • Tubules – Urine will leave via tips of pyramid via the papilla • Papilla o Bases of pyramids o Will empty into calices • Minor calices converge to major calices  drains into renal pelvis which exits the kidneys at the hilum • Lining of the structures (calices, pelvis & ureter) is similar o Transitional epithelium – (expands, contracts & protects) o Lamina prop
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