19 increase or decrease in blood volume dehydration

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Unformatted text preview: gure 44.19 increase OR decrease in blood volume (dehydration) or blood pressure (baroreceptors in various cardiovascular locations) Lecture 7 - Kidney Lecture ADH release triggered by increases in blood osmolality above 280-284 mOsm/kg (osmolality threshold) Lecture 7 - Kidney Lecture ADH release triggered by blood pressure decreases of 5-10% or more Importance of countercurrent blood flow around nephron Importance After glomerulus After blood flows to: 1. Ascending Loop of Henle Into blood Salt Out of blood Water Water (nutrients, O2) (nutrients, 2. Descending Loop of Henle Water Salt (metab. waste, CO2) Additional countercurrent flow: Proximal tubule Salt, water (secretion) Collecting Duct/Loop of Henle: recycle urea to Collecting maintain high mOsm/L in medulla In epithelial cell membranes: - high density of urea transporters - urea leaves collection duct - urea enters ascending Loop of Henle when extra-cellular conc. exceeds 1200 mOsm/L MAINTAINS SOLUTE GRADIENT Urea transporters Urea EXCRETED The greater the mOsm/L value, the more salt/urea concentrated the fluid: - in extracellular fluid when indicated outside nephron - in filtrate when indicated inside nephron Campbell Figure 44.16...
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