renal physiology overview - pp

8/2/2019 Renal Physiology Overview - PP

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Renal physiology

Gross morphology of renal system

Kidney morphology


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Function of kidneys

Homeostasis

Osmoregulation

Volume regulation

Electrolyte concentration regulation

pH regulation Waste products excretion

Secretion of hormones


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Nephron

Definition

Parts


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Types of nephrons

Differences between

Number

Location

Length of loop of Henle

Capillaries accompanying

Role in function


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justamedullarynephron

cortical nephron


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Renal blood flow

Special features of renal circulation

Renal fraction

2 sets of capillaries and role of vasa recta

Efferent arteriolar lumen diameter

High pressure area

Uneven distribution

Autoregulation

Contribution for juxta glomerular apparatus

Renorenal reflex

Effect of hormones on Renal circulation

5000 ml /min1200 goes tokidney alone

blood comesthrough the

afferent arterioleand goes to theglomerularcapillary andforms the exitingefferent arteriol

thre efferentarteriole branches

off and forms theperitubularcapilliry goingdown from thecortex to themedulla next tothe juxtamedularytubules thesemake connections called vasa recta

the efferentarterioles aresmaller or thinnerthan the afferentarterioles this

causes anincrease inpressure thatpushes blooddown thepertitubelarcapilaries

we have highpressure in renalcapilaries toincrase gradientfor diffusion to

help filtration

this is the shuntof blood from onekidney to the

other in case ofinjust


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can be increasedusing dopamineandprostaglandins..so administrationof nsaids willreduceprostaglandins

and reducekidney blood flowon efferentarteriole

eman arterialblood flow

blood flow

180

60

at different

arterial pressuresbetween thisrange theglomerularfilteration staysconstant

this is anexample of autoregulation of anorgan no matterhow much wechange it doesntmodiful the flowrate


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Measurement of renal blood flow

Principle applied

Substance used

Based on the concept

we calculateusing ficksprinciple

quantity ofsubstance takenup by organ =( concentrationdiff) x bloodflowthrough organ

pah para aminohepic acid

clearance volume:-volume ofplasma losing aparticularsubstance in 1minute

so if substance xis being

secreated by theurine it must becoming out ofplasma through apassage offiltration.. as apassing throughthe ducts somesubstance might

be reabsobedand othersreadded to filtrate


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Clearance concept

Definition

Formula

Effective renal plasma flow

Extraction ratio

Total renal plasma flow

Renal blood flow

volume of plasmagetting rid of asubstance in oneminute clearance concept =

concentration of substancein urine - concentration ofsubstance in plasma Xvolune of urine formed perminute


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The following were the measurements from a healthy 33-year-oldvolunteer:

Urine Serum

Inulin 200.0 mg/dl 2.0 mg/dlGlucose 0 80.0 mg/dl

Potassium 50.0 mEq/L 5.0 mEq/L

Uric acid 15.0 mg/dl 3.0 mg/dl

PAH 100.0 mg/dl 0.2 mg/dl

Assuming that hematocrit of 50%, and urine flow of 1 ml/min, which ofthe following is the best estimate of this patients blood flow?

A. 100 ml/min

B. 200 ml/min

C. 500 ml/minD. 1000 ml/min

E. 2000 ml/min


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Factors influencing blood flow tokidney

Sympathetic stimulation

Angiotensin II

Bacterial toxins


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Glomerular filtration rate

Definition

Concept of ultra filtration

Normal value

Filtration fraction

renal physiology overview - pp

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