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Unformatted text preview: 3/19/2009 Renal System, continued I. D rugs I I. Water Regulation I I I. Glomerular Fil tration Rate a. Importance b. Factors c. Renal blood f low] d. Auto regulation I. BP = HR x SV x PR Na + Reabsorption Loop Diuretic (lower Na+ reabsorption in loop of henle) ↓ BP (↓ water volume) Water retention (stimulate carotid and aortic bodies) Cardiovascular system ↑ vasoconstriction Kidneys Renin-angiotensin system ( liver) ↑ HR Angiotensinogen (renin) secreted by kidneys ↑SV Angiotensin I (ACE: angiotensis converting Brain Thirst enzyme) Sympathet ic nervous system Angiotensin I I (st im ulate secret ion of aldosterone from adrenal gland) Steroid hormone Ace inhibitor: inhibit ACE ↑ B P (↑ water volume) Cardiovascular system ↑ vasodilation Kidney ↓ Na+ Reabsorption (ANF, AMP) Water Excretion (Cells increase in atria) Elevate salt intake get more salt, ↑ Water, ↑SV, ↑SP Salt sensitive: BP won’t go up, unless salt sensitive I I. GFR -main function of the kidney is to fil ter blood (the plasma) On average, fil ter about 125ml’s of plasma per minute => 180L/day Plasma volume in blood => 3L (60X/day fil tered) Don’t want RBC in nephron (want to fil ter plasma), in order to fil ter plasma, need hydrostatic pressure to push plasma through barriers) RBC is big and cannot squeeze through slits (bigger cells stay in blood) like RBC, leukocytes (WBC), platelets (want to keep) Small slitsgood thing (keep big cells) -Need pressure to push through small slits Looks like Fick’s law of diffusion B. Factors 1. Net filtration pressure (dictated by BP) (pressure in blood to push fluid through small slits so kidneys can do filtration) 2. Filtration constant 3. Permeability 4. Area of capillaries in glomerulus C. Renal blood flow ↑= more pressure 2 ways to impact pressure Afferent side Efferent side Constrict efferent= more pressure Afferent = less pressure (evoke control on GFR on primarily afferent side) Why afferent side? Area where blood vessel touch nephron (another side for control) ...
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- Spring '09
- Glomerular Fil tration, kidneys ↑SV Angiotensin, fil ter