PHIS 206 1st Edition Exam 3 Study Guide Lectures 20 29 Lecture 20 I Functions of the Kidneys maintain fluid levels maintain electrolytes balance eliminate metabolic waste products II Excretory System kidneys and urinary bladder kidneys surrounded by capsule o inside capsule is the cortex looks like red meat o inside cortex is the dull grey medulla 3 pipes o renal artery entrance of the kidneys o renal vein ureter exit of kidneys o What went in has to what went out III Nephron structure that does kidney stuf Bouman s capsule anatomical cup wrapped around capillaries aferent and eferent arterioles double walled with space in between opens 1st to proximal convoluted tubule proximal convoluted tubule opens to Loop of Henle descending thin and ascending several layers thick o ascending opens to distal convoluted tubule Renal artery carries 25 of fluid IV 2 Types of Nephrons cortical kidneys Bouman s capsule and tubules 80 total juxtamedullary ONLY Loop of Henle 20 total V Blood Supply afferent arterioles 100 that goes into renal artery efferent arterioles break into peritubular capillaries peritubular capillaries 80 around Loop of Henle renal cortex looks like red meat b c it has a large red blood supply Loop of Henle s juxtamedullary are long and rather straight so peritubular capillaries around Loop are long and straight Peritubular capillaries known as vasa recta meaning long VI 3 Processes 1 Filtration process in which fluid is pushed out of the plasma to Bouman s capsule known as glomerular plasma w protein removed filtered tubular identical to plasma but no proteins so blood in efferent has more protein than afferent 2 Reabsorption as tubular fluids move along nephron some things are reabsorbed active passive transport 3 Secretion some things are secreted out using plasma what comes out will not be same as what was in Bouman s capsule VII Filtration glomerulal capillaries drain into arterial vein pressure in glomerulal capillaries is higher glomerulal capillaries not in straight line look like spaghet vary pressure by constricting relaxing aferent or eferent filter by manipulating arterioles that feed it 180 L day 125 mL min normal glomerular filtration rate GRF avg urine volume 1 L day reabsorb 179 L day VIII Reabsorption reabsorb 99 of solutes using active transport about 40 45 of solutes in plasma are Na ions must reabsorb 99 so Na ions must be absorbed too therefore use ACTIVE TRANSPORT IX Pressure Difference Bouman s capsule hydrostatic pressure 50 mmHg in glomeruli Pressure pushing in colloid osmotic pressure 30 mmHg in glomeruli Hydrostatic pressure 10 mmHg in Bouman s capsule Net driving force 10 mmHg gives Gfr or 125 min o directly proportional to pressure 10 mmHg kept constant in real life When arterial pressure increases pressure in glomeruli stays same b c we constrict aferent arterioles Gfr is constant X No urine production when 60 mmHg of renal curve or less b c when arterial pressure is low pressure in glomeruli cannot get bigger Reabsorption and Active Transport reabsorption in arteriole tubules is high 100 glucose reabsorbed if healthy b c no glucose in urine 1 mg mL of glucose in plasma 1 g 8 min reabsorbed Reabsorb by active transport same with amino acids vitamins etc Active transport systems that make this happen MUST reabsorb Na ions to reabsorb other things more than 99 of filtered Na is reabsorbed Na Reabsorption 80 in proximal 12 in Loop of Henle and 8 in distal tube distal tubule can control what we reabsorb Hypertensive take of Na in diet b c plasma is enlarging reabsorption problems Lecture 21 I Glucose 100 reabsorbed for a normal person only fuel brain can use active transport system all reabsorbed in proximal tubule must have a carrier protein that is saturable input of Energy moves it outside nephron finite capacity that the protein can carry Maximum rate transport maximum amount entering tubular load o concentration in glomerulal filtrate filtration rate Transfer Maximum Tm Glucose 400 mg min Normal Tubular Load 125 mg min 100 gets reabsorbed in proximal tubule Plasma Glucose Level 1 min 125 mg min 0 in urine 2 min 250 mg min 0 in urine 3 min 375 mg min 0 in urine 4 min 500 mg min 100 in urine greater than T 400 mg min 5 min 625 mg min 225 in urine 6 min 750 mg min 350 in urine m II Diabetes Diabetes melatis honeylike Diabetes insipitis without sugar III Active Reabsorption of Na causes passive reabsorption of Cl since cation of Na and anion of Cl must equal out When Na and Cl reabsorbed water follows osmotically IV Passive Reabsorption things can difuse out of nephron passively best example urea non toxic most aquatic animals produce ammonia that difuse away fast before storage we have to convert toxic ammonia to something safer convert ammonia into urea urea is 2nd fastest to difuse after water osmotically reabsorb water as water decreases urea increases urea difuses up when left in high concentrations sequence of events 1 Actively transport solutes 2 Water follows PASSIVE 3 Things that can diffuse urea will diffuse down conc gradient PASSIVE urea more in plasma V Secretion add stuf to tubule add Extracellular Fluid in tubules which is plasma in capillaries actively transfer into nephron from capillaries MOST IMPORTANT THING SECRETED H proximal distal collecting vessel Number of anions actively secreted too Anionated groups attach to drugs and are excreted through urine VI Urine Output 1 2 L day normal urine output 1 mL min Gfr 180 L day Reabsorbed 179 L day urine output 1 L day VII Plasma Clearance know how much you are excreting and concentration of stuf in plasma then you know the number of mL of plasma to provide some specific compound each minute Definition of Plasma Clearance plasma clearance tells you how efficiently you are removing the compound from the kidneys plasma clearance large to provide stuf that is actively secreted VIII Inulin freely filtered but not reabsorbed or secreted amount in glomerulal filtrate is amount that entered if you measure inulin clearance you are actually measuring the Gfr not normal in blood unless you love garlic or artichokes IX Creatinine creatinine clearance also gives you Gfr not reabsorbed weakly secreted more commonly used to measure Gfr X p Aminohippuric acid PAH actively secreted so almost none left in renal vein whatever enters winds up in urine mainly plasma clearance for PAH renal plasma flow renal blood flow is approximately 2 plasma flow Lecture 22 I Regulation juxtamedullary 20 nephrons