PHIS 206 1st EditionLecture 22Outline of Last Lecture I. GlucoseII. DiabetesIII. Active Reabsorption of Na+IV. Passive ReabsorptionV. SecretionVI. Urine OutputVII. Plasma ClearanceVIII. InulinIX. CreatinineX. p-Aminohippuric acid (PAH)Outline of Current Lecture I. RegulationII. If Ascending + Descending Not ParallelIII. Countercurrent ImportanceIV. HypothalamusV. BalanceVI. Normal Body FluidsVII. Regulation of H+ ConcentrationCurrent LectureI. Regulation-juxtamedullary: 20% nephrons; project out of cortex and have blood supply that follows straight vessels involved (vasa recta) fluid in the thick and thin limbs are running in the opposite directiono decrease in ascendingo increase in descending o thin (descending)o thick (ascending) countercurrent flow/mechanism: generates stable osmotic gradient in renal medulla o positive feedback o system at rest (no blood, no urine, etc…flow) osmolarity = 310 milliosmol/LThese 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. Parallelo start fluid movement fluid pushed through Loop of Henle and into collecting duct still 310 milliosmol/L in cortex medullao turn on Na+ plump Na+ removed from ascending to permeable descending higher Na+ will cause more Na+ in descending, so Na+ in ascending will go up, pumps go faster greater concentration = greater diffusion conc. reached 1200 mOsm deep into medullaII. If Ascending + Descending Not Parallel-thick is permeable to Na+-since there is a barrier between thin and thick limbs, there will be no effect on the thin limb as Na+ diffuses out or into thick limb -Therefore, we need a countercurrentIII. Countercurrent Importance-if collecting duct is impermeable to water, then 310 entering = 310 exiting- if collecting duct is permeable to water, then 310 entering = 1200 exiting-75% of volume must have been reabsorbed-if we could change the water permeability of the collecting duct, we can change urineconcentrationIV. Hypothalamus-osmoreceptors: cells that monitor the osmolarity of plasma plasma osmolarity increases, volume decreases, ADH releasedo antidiuretic hormone (ADH): reduces urine production increases water permeability of collecting duct adds more fluid to be absorbed plasma osmolarity decreases, less ADH, less urine secreted, small osmolarity EX.) sweat at gymo lose 2 L of watero arteriole pressure decreases, increase in plasma osmolarityo urine darker, more concentrated EX.) drink pitcher of iced teao increase plasma volume, decrease plasma osmolarityo less concentrated urineo rid extra fluid Maintain normal plasma volume and arteriole pressure: countercurrent mechanismV. Balance-stable or neutral balance: input = output NORMAL STATE-positive balance: input > output FEVER-negative balance: output>input HYPOTHERMIC-fever shivering: using muscles to produce heat sweating inhibited temp. goes up, sweatVI. Normal Body Fluids-60% water in body Intracellular (2/3 of fluid in body) Extracellular (1/3 of fluid in body)VII. Regulation of H+ Concentration-Log H+ (change in 1 Log unit is a 10-fold change)- H+ in (aq) soln. can run from 10-1 to 10-14 M, so we use log scale to allow us to express in units of 10-as conc. goes up, logarithm goes up-from -1 to -14 we use –log [H+] to make the numbers positive- H+ = pH = -log [H+]-any reversible rxn : AB A + B-
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