week 11 notes for exam 6
week 11 notes for exam 6 PHYS 215
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This 0 page Class Notes was uploaded by Jennifer Fry on Wednesday November 4, 2015. The Class Notes belongs to PHYS 215 at Ball State University taught by Zamlauski-Tucker in Summer 2015. Since its upload, it has received 20 views. For similar materials see Human Physiology in Science at Ball State University.
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Date Created: 11/04/15
Week 11 notes Physiology 11415 Kidney Functions 0 Maintaining H20 balance 0 Maintaining proper osmolarity of uids 0 Regulating the quantity and concentration of the Extra Cellular Fluid ECF Maintaining proper plasma volume Maintaining acidbase balance pH Eliminating of end products Excreting foreign compounds Producing erythropoietin Producing renin important in salt conservation 0 Conversion of vitamin D to the active form Pathway of Urinary Flow 0 Kidneyproduction of urine 0 Renal pelvis collects the urine from the kidney 0 Ureter carries the urine from the renal pelvis to the urinary bladder 0 Urinary bladder stores urine until release 0 Urethra carries urine to outside Nephron o Smallest unit capable of urinary production Glomerulus o Balllike structure with capillaries passing through it water and solutes from the blood lter into the tubular part of the nephron from here Afferent arteriole o Supplies the nephron with blood Efferent arteriole 0 Leaves the glomerulus with the remainder of blood Peritubular arteriole o Divides from the efferent arteriole and feeds the renal tissue The nephron tubular component 0 Bowman s capsule tubule surrounding the glomerulus that collects the ltered uid 0 Proximal tubule leaves Bowman s capsule passing the uid through a convoluted path down to the loop of Henle 0 Loop of Henle forms a Ushape dipping from the cortex into the renal medulla before ascending back into it o Juxtaglomerular apparatus runs next to the glomerulus o Distal tubule twists around until it drains into the collecting duct 0 Collecting duct collects uid from 8 nephrons and drains it into the renal pelvis The nephron o Cortical nephrons lie in the outer layer of the cortex 0 Juxtamedullary nephrons lie in the inner layer of the cortex next to the medulla OOOOOO o Vasa recta the peritubular capillaries ofjuxtamedullary nephrons that form hairpin loops 0 Renal processes 0 Glomerular ltration nondiscriminating ltration of protein free plasma 0 Tubular reabsorption selective movement of essential ltered substances from the tubular lumen to the peritubular capillaries o Tubular secretion selective movement of certain substances from the peritubular capillaries into the tubular lumen fill it in t it u l e r Hi tr e ti it til Sterling s hdy phtheeieg implies Elltilli tln39eugh e seini pert neehe tepillei39y l39ijt iveetetie l TilI39rEEa iwlllt E ehj fluitle iiiJI tiy39 f l q 39i39i lquotltllE the enemie peeeeut e hilthe ellnli39 rih lpreteihji helds quothid within the eepiltury Sterling Fui39eee li f tt ii l telitistlletrller lhltitit pre39esuIe quot55 rhian higher then tit tt tt t l I an hitjewel We due in lei39 e r nt eri eritije Pleerrte eelleit preeeui39e 3li mmHg the pleente pt titein tell hehihdi wente it t ntnee heel ihtu the eepi llerge but rheie leeuee Ell jti Etitetre l3crehrnen39e eepeule litmittste39tle pt t 39 intn eeei39t by fluid n the illillliitl pert sutmjthe tubule t39tlll l39liiti ltiit tiut butquot l39flci rtt39 it l E It hi 1e itet L IJIIJE39II laaui e hell 1T 4 i ttttt He The 5miteeuler eelgril l l gtioiltgtltgtlt Glomerular Filtration Rate GFR o GFRKf8net ltration pressure 10 o Kf ltration coef cientdepends on the permeability how leaky it is of the glomerular membrane and the amount of surface available for solutes to cross 0 Net ltration rate glomerular blood pressure the net hydrostatic pressure So NFR55 mmHg 45mmHg or 10 mmHg Autoregulation of the GFR o 2 mechanisms Myogenic muscle produced mechanism a erent arteriole vascular smooth muscle automatically contracts with an increase in arteriole pressure Tubuloglomerular feedback mechanism involves macula densa cells which contain granules part of distal convoluted tubules DCT part ofjuxtaglomerular apparatus Tubuloglomerular Feedback 0 Macula densa cells secrete a vasoconstrictor when 1 Lots of ltrate is present and ow is high 2 Osmolarity is high especially sodium and chloride content because not as much is being reabsorbed o The vasoconstrictor constricts afferent arterioles which decreases ow D decreases ltration Allows increased reabsorption by slowing movement of ltrate through the nephron Mesangial cells 0 O 0 Located in the interstitium of the glomerulus or the mesangium Specialized smooth muscle cells which can alter gomeruar surface area and hense GFR through their contraction They also have macrophagelike properties and synthesize the matrix proteins of the magnesium These properties and changes or expansion of the mesangial matrix have important pathogenic consequences in gomeruar diseases Tubular reabsorption occurs via 2 processes 0 O Diffusion Substances urea and lipid soluble compounds in the proximal tubule move down their respective concentration gradients into the peritubular capillary The concentration gradients are established by the movement of water into the proximal tubule The movement of uid from the ISF into the peritubular capillaries occurs via Starling Forces Mediated transport Substances moving from the tubular lumen to the peritubular capillaries against their electrochemical gradient move via transcellular epithelial transport 0 Transepithelialtransport O O Involves the movement of molecules through 2 membranes 1 The luminal membrane lumen side 0 The surface of the cell lining the lumen is called the apical membrane 2 The surface in contact with the extracellular uid is called the basolateral membrane The characteristics of these 2 membranes are different in terms of their complement of ion channels and transport proteins The electrochemical gradients for the molecules which are moved are also different with respect to the concentrations in the lumen epithelial cell and plasma side 0 Transepithelial transport of sodium 0 O The movement of Na ions from the lumen to the epithelial cell occurs via diffusion through a Na channel in the luminal membrane of the epithelial cell The movement of Na out of the epithelial cell and into the ISF and hence the plasma occurs through the NaK ATPase transporter located in the basolateral membrane I m In a epithelial li aiisimrf tilquot 3 image an n til m i n I1 t ii i iii 35 i limnat all ginnae and amino raids I39E hiniiill h d 511 I fa I 39 n WEEaid Llama5 ILI39tllrma n rd i Reabmrptitin is in exuh nge for and Tenure in the Zl l ti i39ll l lfuljule use ng39czrit unit or ai rr iTlie iinu veme i l gluuuae and 311111 ugainal their cumenlralium gradient from the lumen into lie epithelial cell ctiupled it the nitjlta39eifnenl tall inns down heir cuijcenlratinn gradient gtlltgtllt Glucose and Amino Acid Reabsorption O O Sodiumglucose symport is located on the apical membrane that lines the lumen Extracellular sodium binds to the symport This causes a conformational change that creates a high af nity binding site for glucose When glucose binds the symport changes conformation again to an open channel to the inside of the cell Sodium is released as it moves down its concentration gradient 0 Unbinding of sodium causes the glucose binding site to become low af nity and glucose is released This process requires no energy no ATP Secondary Transport 0 O 0 However as transport continues sodium accumulates in the cell destroying the sodium concentration gradient Transport will stop if the concentration gradient is destroyed To maintain the sodium concentration gradient sodiumpotassium pumps ATPases are located in the basolateral membrane The pump keeps intracellular sodium levels low so the symport can keep functioning Renal sodium absorption 0 O The regulation of total body Na is achieved through the baroreceptors and osmoreceptors As Na is the major electrolyte in plasma any change in Na ion concentration will affect plasma volume and hence blood pressure 0 Low blood pressure activates the baroreceptor re ex An increase in the activity of sympathetic nerves causes a constriction of the renal arterioles that lowers GFR and increases Na reabsorption The reninangiotensin system 0 Acts to stimulate the secretion of aldosterone from the adrenal cortex 0 Aldosterone increases the reabsorption of Na ions by the collecting ducts by promoting the expression and synthesis of the transport proteins involved in moving Na ions That is aldosterone promotes the expression and synthesis of Na channels on the luminal membrane and the NaK ATPase on the membrane 0 Stimulation of the renal sympathetic nerves as a result of the initiation of the baroreceptor re ex stimulate the juxtaglomerular cells to release renin o The juxtaglomerular cells macula densa cells are sensitive to pressure and constitute intrarenal baroreceptors A reduction in renal blood pressure as a result of low Na stimulated the juxtaglomerular cells to release renin Actions of Renin o Circulating renalderived renin cleaves hepaticderived angiotensinogen to form the decapeptide angiotensin I Ang I 0 Ang I is converted by ACE in the lungs and tissue to active angiotensin II ANGIDTEMSMO GEN AspAraValT y39riiaHisPmPhe IlIssaLauieuaVaiaTyr ANIGiDTEMSiM I i AspArgMaiTyrllieHisPmPhia IiilsaLeru c maxyipeptidasa Ace Chymase acathapsilin ANGIDTENSMN iii i AspArgVaiTyrhiI eJiiepmapihe Swiu39m depletion Minieneimgen mined pressure Sympathetic siimularion iii adrenoeeptzor 39 f Arterial venous Domination Sympathetic erimuleiien 39 ADi i secretion Direct renai e ecie 7 Wieiensin iii I I KQeIeeee quot quotSalt and water retention Fig 63 Femal39ion and auctions of maintainsin Iii ADH aritidiuretic iioirmne AiZEr 3ngimeieincorwerring enzyme