PHIS 206 1st Edition Lecture 20 Outline of Last Lecture I Muscles II Cardiac Muscle III Respiration Outline of Current Lecture I Functions of the Kidneys II Excretory System III Nephron IV 2 Types of Nephrons V Blood Supply VI 3 Processes VII Filtration VIII Reabsorption IX Pressure Difference X Reabsorption and Active Transport Current Lecture 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 These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 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 No urine production when 60 mmHg of renal curve or less b c when arterial pressure is low pressure in glomeruli cannot get bigger X 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
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