PHIS 206 1st EditionLecture 20Outline of Last Lecture I. Muscles II. Cardiac MuscleIII. RespirationOutline of Current Lecture I. Functions of the KidneysII. Excretory SystemIII. NephronIV. 2 Types of NephronsV. Blood Supply VI. 3 ProcessesVII. FiltrationVIII. ReabsorptionIX. Pressure DifferenceX. Reabsorption and Active TransportCurrent LectureI. Functions of the Kidneys-maintain fluid levels-maintain electrolytes balance-eliminate metabolic waste productsII. Excretory System-kidneys and urinary bladder-kidneys surrounded by capsuleThese 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 pipeso renal artery: entrance of the kidneyso renal vein/ureter: exit of kidneyso What went in has to = what went outIII. 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 fluidIV. 2 Types of Nephrons-cortical: kidneys, Bouman’s capsule, and tubules; 80% total-juxtamedullary: ONLY Loop of Henle; 20% totalV. 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 Processes1.) 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 afferent2.) Reabsorption: as tubular fluids move along nephron, some things are reabsorbed-active + passive transport3.) Secretion: some things are secreted out using plasma-what comes out will not be same as what was in Bouman’s capsuleVII. 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/dayVIII. 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 TRANSPORTIX. 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/mino 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 biggerX. 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 reabsorbother 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
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