PHIS 206 1st Edition Lecture 22 Outline of Last Lecture I Glucose II Diabetes III Active Reabsorption of Na IV Passive Reabsorption V Secretion VI Urine Output VII Plasma Clearance VIII Inulin IX Creatinine X p Aminohippuric acid PAH Outline of Current Lecture I Regulation II If Ascending Descending Not Parallel III Countercurrent Importance IV Hypothalamus V Balance VI Normal Body Fluids VII Regulation of H Concentration Current Lecture I 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 direction o decrease in ascending o increase in descending o thin descending o thick ascending Parallel 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 L 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 start fluid movement fluid pushed through Loop of Henle and into collecting duct still 310 milliosmol L in cortex medulla o 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 medulla II 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 countercurrent III 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 urine concentration IV V Hypothalamus osmoreceptors cells that monitor the osmolarity of plasma plasma osmolarity increases volume decreases ADH released o 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 gym o lose 2 L of water o arteriole pressure decreases increase in plasma osmolarity o urine darker more concentrated EX drink pitcher of iced tea o increase plasma volume decrease plasma osmolarity o less concentrated urine o rid extra fluid Maintain normal plasma volume and arteriole pressure countercurrent mechanism 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 sweat VI 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 k A B AB
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