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Unformatted text preview: Fluid & Ion Balance Kidneys : control urine concentration Aldosterone: ↑ Na + reabsorption Vasopression: ↓ H 2 O reabsorption Atrial natriuretic peptide: ↓ Na + & H 2 O Why is maintaining fuid balance is important For normal cell Fxn?- By aFFecting [Na+] in cells, infuence water fow in and out oF cells- Also regulate thru intake and excretion oF water From cells How are daily water intake and excretion balanced?- Exogenous appearance oF water via diet: 2.2L/day- Endogenous appearance oF water via metabolic production: 0.3L/day- Disappearance via urine (1.5L/day), via sweat & breath (0.9L/day) and Feces (0.1L/day) Urine fows From nephrons oF renal cortex and medulla into renal pelvis- Renal artery carries blood to kidneys, allowing blood to fow thru cortex -> medulla- Disposed water fows down calyces into renal pelvis, which drains into ureter & bladder- ¡iltered blood returns to body via renal vein extracellular fluid (1/3) interstitial fluid: plasma (75%:25% of ECF) ~55% water intracellular fluid (2/3) blood vessel (varies with sex, age) cell Intake + Metabolic = Output production food drink 0 3 L/day urine (1 5 L/day) food, drink (2.2 L/day) 0.3 L/day urine (1.5 L/day) sweat, breath (0.9 L/day) feces (0.1 L/day) PSL302Y: Lecture 07, by ProF. Lam Mon., Sept. 27, 2010 1 oF 5 The nephron is the fxnal unit of the kidney- First site of ¡ltration at glomerulus- Hormonal actions on reabsorption of water and minerals at collecting duct; receptors found here Urine is formed in the nephron by ¡ltration, reabsorption, secretion- Aldosterone: role in regulating water reabsorption & in regulating blood pressure Na + K + K + H 2 O Renal juxtaglomerular cells secrete “renin” Renin: enzyme involved in controlling aldosterone release Juxtaglomerular cells senses changes in blood pressure, & is responsible for secreting...
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- Fall '11
- Nephron, Ion Balance, Prof. Lam