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L6- Urinary SystemSlide 1: The Urinary SystemSlide 2: Functions of the Urinary System- Regulate aspects of homeostasiso Water balance with Antidiuretic Hormone (ADH)o Acid- base balance in the blood by regulating plasma pHo Regulate plasma ionic composition, electrolytes with aldosteroneo Regulate blood pressure and blood volume by regulating plasma volume and plasma osmolarityo Red blood cell production: secrete erythropoietins (stimulates RBC production when low oxygen levels are detected) and rennin (aka angiotesinogenase released in low blood pressure)o Activated vitamin D3 (calcitriol)- Elimination of waste products- metabolic wasteso Nitrogenous wasteso Toxinso DrugsSlide 3: Developmental Aspects of the Urinary System- Functional kidneys are developed by the third month- Urinary system of a newborno Bladder is smallo Urine cannot be concentrated for first 2 months Therefore urinating a loto Void 5-40 times per daySlide 4: Developmental Aspects of the Urinary System- Control of the voluntary urethral sphincter does not start until the age of 18 monthso Cultural – tropical climates- Complete nighttime control may not occur until the child is 4 years oldo Circadian Rhythm Different hromones change during different times of night ADH increases at night- conserves water so you urinate less Alcohol inhibits ADH- Urinary infections are the most common problems before old age, Escherichia coli (E. coli), a type of bacteria, accounts for 80% of UTI (uninary tract infections)Slide 5: Structures of the Urinary System- Kidneys form urine- Ureters transport urine from kidneys to bladder- Bladder stores urine- Urethra excretes urine from bladder to outside of bodySlide 6: Urinary Bladder- Smooth, collapsible, muscular saco Stretch and recoilo storage- Temporarily stores urine, a moderately full bladder is about 5 inches long and holds about 500 m L of urine- Trigone is a triangular region of the bladder baseo Three openings Two from ureters One to the urethrao In males, the prostate gland surrounds the neck of the bladderSlide 7: Position and shape of a distended and an empty urinary bladder in an adult male- See Diagram- Enlarge prostate= pushes on bladder and pinches urethra Slide 8: Urinary Bladder Wall- Three layers of smooth muscle collectively called the detrusor muscle- Mucosa made of transitional epitheliumo Stretch and recoil- Walls are thick and folded in an empty bladder- Bladder can expand significantly without increasing internal pressure Slide 9: Kidney Features- The right kidney is slightly lower than the left (due to position of liver)- Renal hilum is a medial indentation where several structures enter or exit the kidney (ureters, renal blood vessels, and nerves)- An adrenal gland sits atop each kidneyo Donating kidney AND adrenal glandSlide 10: Blood Supply- Specialized for filtration- One- quarter of total blood supply of the body passes through the kidneys each minute- Renal artery provides each nidney with arterial blood supply- Renal artery divides into segmental arteries  interlobar arteries arcuate arteries cortical radiate arteries- Venous blood flow: cortical radiate veins arcuate veins interlobal veins renal veinsSlide 11:Slide 12:Slide 13:Slide 14:Slide 15:Slide 16:Slide 17:Slide 18:Slide 19:Slide 20:Slide 21:Slide 22:Slide 23:Slide 24:Slide 25:Slide 26:Slide 27:Slide 28:Slide 29:Slide 30:Slide 31:Slide 32:Slide 33:Slide 34:Slide 35:Slide 36:Slide 37:Slide 38: Maintaining Water Balance- Diluted urine is produced if water intake is excessive- Less urine (concentrated) is produced if large amounts of water are list (sweating/ dehydration)- Proper concentration of various electrolytes must be present- osmolaritySlide 39: Counter- Current Multiplier in the Loop of Henle- Osmotic gradient established by counter- current multiplier- Dependent on Loop of Henle- Descending Limbo Permeable to watero No transport of Na+, Cl-, or K+- Ascending Limbo Impermeable to watero Transport of Na+, Cl-, and K+- Constantly being maintained- Two things moving in the opposite directions to increase - Deeper in medulla= 1400o Most concentrated urineo Function= increase concentrated urine- Animals that live in dry areas= more intense max concentration- Water leaves descending, filtrate concentration goes up- Ascending- ion permeableo Ions leaveo Concentrations of filtrate goes down Slide 40: Counter- Current Multiplier- Urine concentration and dilution mechanismso The countercurrent exchanger mechanism The capillaries of the vasa recta function as countercurrent exchangers, because the direction of blood flow around theloop of Henle is opposite to the direction of filtrate flow aroundthe loop- Vasa recta- counter current than loop of Henle- The extra ions omitted by the loop of Henle remain in the medullaSlide 41: Result of Counter- Current Multiplier- Fluid in proximal tubule 300 mOsm/ liter- Fluid (filtrate) in descending limp- osmolarity increases as it descends- Fluid in ascending limb- osmolarity decreases as it ascends - Prevents dissipations of concentration gradient in medulla because eit collects the water from the descending loopSlide 42: Vasa Recta- Prevents dissipation of osmotic gradient while supplying nutrients and removing wastes - Special/ important functionSlide 43: Regulation of Water and Electrolyze Reabsorption- Osmoreceptorso Cells in the hypothalamuso React to changes in blood composition by becoming more active as osmolarity increaseso Osmolarity- actually works with compositions o Works with baroreceptorsSlide 44: Water Reabsorption in Distal Tubules and Collecting Ducts (ADH)- Dependent on osmotic gradient established by counter- current multiplier- Dependent on epithelium permeability to water- Water permeability dependent on water channelso Aquaporin -3 : present in basolateral membrane alwayso Aquaporin 2- present in apical membrane only when ADH is present in blood - ADH conserves watero Not going into it accept that it is a G- protein Binds to G- protein  cascade Kinase- phosphoralates  changes shape  activateso Aquaporin 3 is always openo But water is not always permeable in collecting duct (this is where aquaporin 2 comes in )Slide 45: Permeable Membrane in Presence of ADH- ADH stimulates insertion of water channels (aquaporin- 2) into apical membrane, water can permeate membrane and be reabsorbed by osmosis- Max osmolarity urine = 1400 mOsm- Water will freely go out because the concentration is


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UMD BSCI 202 - Urinary System

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