Physiology 2130 Lecture Notes - Lecture 8: Renal Function, Renal Corpuscle, Colloid
30 Apr 2018
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Glomerular Filtration & Calculations
1. Glomerular Filtration
-healthy kidneys produce large volume of filtrate/day (180L)
-due to number of pressures in renal corpuscle
-make about 2L of urine/ day
• Net Filtration Pressure
-sum of forces produces is the net filtration pressure
-is 10mmHg, then proper filtration can occur
-if NFP is positie = plasa filters ito oa’s spae
-if NFP is 0 or negative = plasma will not filter out
-
• Pressures that affect glomerular filtration
1. Hydrostatic Pressure of Glomerular Capillaries (PGC)
-pressure caused by blood flowing into glomerulus
-promotes filtration
-55mmHg
2. Colloid Osmotic Pressure of Glomerular Capillaries (CGC)
-pressure caused by presence of proteins in glomerulus
-inhibits filtration
-30mmHg
3. Hydrostatic Pressure of Bowmans Capsule (PBC)
-pressure aused y filtrate reaiig i oa’s spae
-inhibits filtration
-15mmHg
4. Colloid Osoti Pressure of Boa’s apsule (CBC)
-pressure aused y presee of proteis i oa’s apsule
-promotes filtration
-0 mmHg
• Calculate Net filtration pressure
= 10 mmHg –good what we want
-if higher than 10, you are filtering more fluid do’t at
-if lower than 10, you are filtering less do’t at
• Glomerular Filtration Rate (GFR)
-aout of fluid that’s filtered per uit tie ito oas spae fro gloerular
capillaries
-normal rate is 180L/day
find more resources at oneclass.com
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Affected By:
• Net filtration pressure
-mostly by PGC
-filtration coefficient (mostly affected by spaces inbetween podocytes and
integrity of basal lamina)
-influenced by BP (if BP increases so does net filtration)
• Filtration Coefficient
-mostly affected by spaces in between podocytes & permeability of barriers b/w
apillary ad Boa’s Capsule
2. Autoregulation of GFR
-function to keep GFR fairly constant throughout the day
• Myogenic Response
-afferent arteriole stretches
-stretch sensitive ion channels open
-smooth muscle cells depolarize
-voltage gated Ca channels in smooth muscle open
-smooth muscle of afferent arteriole contracts (constricts afferent)
-blood flow decreases in glomerulus
• Tubuloglomerular Feedback
-regulate GFR locally
-Macula Dense cells:
-salt detectors in the ascending loop of henle
-sense flow
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Healthy kidneys produce large volume of filtrate/day (180l) Due to number of pressures in renal corpuscle: net filtration pressure. Sum of forces produces is the net filtration pressure. If nfp is positi(cid:448)e = plas(cid:373)a filters i(cid:374)to (cid:271)o(cid:449)(cid:373)a(cid:374)"s spa(cid:272)e. If nfp is 0 or negative = plasma will not filter out: pressures that affect glomerular filtration. 55mmhg: hydrostatic pressure of glomerular capillaries (pgc, colloid osmotic pressure of glomerular capillaries (cgc, hydrostatic pressure of bowmans capsule (pbc, colloid os(cid:373)oti(cid:272) pressure of bo(cid:449)(cid:373)a(cid:374)"s (cid:272)apsule (cbc) Pressure (cid:272)aused (cid:271)y prese(cid:374)(cid:272)e of protei(cid:374)s i(cid:374) (cid:271)o(cid:449)(cid:373)a(cid:374)"s (cid:272)apsule. Pressure caused by presence of proteins in glomerulus. Pressure (cid:272)aused (cid:271)y filtrate re(cid:373)ai(cid:374)i(cid:374)g i(cid:374) (cid:271)o(cid:449)(cid:373)a(cid:374)"s spa(cid:272)e. If higher than 10, you are filtering more fluid (cid:894)do(cid:374)"t (cid:449)a(cid:374)t(cid:895) If lower than 10, you are filtering less (cid:894)do(cid:374)"t (cid:449)a(cid:374)t(cid:895: glomerular filtration rate (gfr) A(cid:373)ou(cid:374)t of fluid that"s filtered per u(cid:374)it ti(cid:373)e i(cid:374)to (cid:271)o(cid:449)(cid:373)a(cid:374)s spa(cid:272)e fro(cid:373) glo(cid:373)erular capillaries. Filtration coefficient (mostly affected by spaces inbetween podocytes and integrity of basal lamina)
