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28 Cards in this Set
- Front
- Back
Major Urinary System Functions
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Water + ion balance*, excretion of metabolic wastes + foreign substances, hormone production, ECF volume, osmolarity, acid-base balance
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Urinary System Components
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Kidneys, ureters, bladder, urethra
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Retroperitoneal Cavity
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Between abdominal peritoneum and back bones + muscles
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Kidney Layers
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Outer cortex, inner medula, renal pelvis (upper end of ureter)
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Nephron Portal System
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Blood from renal arteries flows into afferent arterioles + enters glomerular capps. Leaves out efferent arterioles into peritubular capps in juxtamedullary nephrons + exits thru renal vein.
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Nephron Anatomy
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Renal corpuscle (glomerulus + Bowman's capsule), proximal tubule, loop of Henle, distal tubule + collecting duct.
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Kidney Functions
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Filtration, reabsorption, secretion.
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Filtration driven by...
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Hydrostatic pressure, colloid osmotic pressure, and fluid pressure.
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Filtration Fraction
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% total plasma volume that filters into tubule
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Renal Corpuscle Filtration Barriers
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Capillary endothelium (fenestrated capillaries), basal lamina (course sieve), Bowman's capsule epithelium (filtrations slits)
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Glomerular Filtration Rate
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Volume that filters into Bowman's capsule per unit time
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GFR Regulation
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Net filtration pressure, filtration coefficient, total SA available
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GFR Influences
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Hydrostatic pressure (pos.); colloid osmotic pressure (neg.) and fluid pressure created in Bowman's (neg.)
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GFR Arteriole Resistance
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Afferent resistance (site of most reg.) dec. hydrostatic pressure + GFR; efferent resistance inc. glomerular pressure + GFR
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Autoregulation
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Maintains constant GFR thru myogenic response, tubuloglomerular feedback, and hormones
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Myogenic Response
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Inc. blood pressure stretches artery smooth muscle to vasoconstrict. Dec. blood pressure results in maximal vasodilation
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Tubuloglomerular Feedback
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Paracrine signaling mechanisms thru which loop of Henle influences GFR: macula densa senses [Na+] while granular cells secrete renin
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Hormone Autoregulation
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Sympathetic neurons innervate alpha-receptors to induce vasoconstriction; angiotensin II vasoconstricts; prostaglandins vasodilate
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Reabsorption Routes
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Transepithelial transport, paracellular pathway, urea (passive), or plasma proteins (via transcytosis)
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Reabsorption of Solutes + Water
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Na+ transport creates electrochemical gradient, drives anion reabsorption, water osmotically follows solutes, dilutes lumen, solutes diffuse into ECF
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Na+-linked Glucose Reabsorption
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Apical Na+-glucose cotransporter (SGLT, active), basolateral glucose transporter (GLUT)
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Saturation
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Max. rate of transport occurs when all available carriers occupied by substrate
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Filtration, Reabsorption, Excretion Relationship
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When no secretion occurs, amt. excreted = amt. filtered - amt. reabsorbed; normal conditions, filtration=reabsorption; renal threshold, filtration > reabsorption & excretion begins
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Secretion
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Active transport of molecules from ECF into neph. lumen. Enhances neph. excretion. Competitive process (ex. penicillin + probenicid)
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Excretion
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Filtration - reabsorption + secretion
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Clearance
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Rate @ which solute leaves the body, by excretion or metabolism
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Inulin
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Admin. by continuous IV infusion, 100% excreted, so clearance = GFR
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Creatinine
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Endogenous, in muscles via PCr breakdown, 99% excreted, but need not be admin.
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