Renal Physiology Review-S

8/7/2019 Renal Physiology Review-S

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-Ex ertise

of the KidneyPT 515

Clarkson University

Physical Therapy Program

on em g o, c


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Learnin Ob ectives1. Overview of renal anatomy and the nephron

2. Explanation of kidney function1. The 3 basic processes of urine formation

2. Control of BP and Water balance

3. secretion into tubules

+ +. , ,amino acids

4. Explanation of the important renal functional

milestones


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How many patients with kidney disease?

23 million adults age 20 and above Whats the incidence?

,

What are the main causes?

Diabetes, hypertension, glomerulonephritis, and polycystic kidney.

ESRD due to diabetes is increasing at an annual rate of more than11% per year.

ow many ave a ney transp ant In 2007 17,000

How many are waiting for a transplant?

>54,000 patients are awaiting for a donnor


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Chan e in fre uenc and uantit of urine assed

especially at night (usually increase at first) Blood in the urine (haematuria)

Foaming urine

Puffiness around the eyes and ankles (oedema) ,

are located)

Pain or burnin when assin urine.


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,

Generally feeling unwell

oss o appet te

Nausea and vomiting Shortness of breath


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Eat lots of fruit and vegetables including legumes (peas or beans) and

grain-based food like bread, pasta, noodles and rice.

Eat only small amounts of salty or fatty food.

Drink plenty of water instead of other drinks.

Maintain a healthy weight.

Exercise regularly.

Dont smoke.

Alcohol has a profound negative effect in eletrolyte, fluid balance and acid-base balance

Have your blood pressure checked regularly.

o t ngs t at e p you re ax an re uce your stress eve s. A low protein diet can treat & prevent some kidney conditions and postpone

dialysis


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Renal Multitasking

Regulation of Water and Electrolyte Balance of body fluids (extracellular)

Excretion of Metabolic Waste

, ,specifically drugs affecting body function)

Regulation of Red Blood cell production

Regulation of Vitamin D production

Gluconeogenesis


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Filtration (youtube)

Blood pressure Water and solutes across glomerular capillaries

Reabsorption (youcap)

The removal of water and solutes from thefiltrate

Secretion ou2tube

Transport of solutes from the peritubular fluidinto the tubular fluid

Excretion = urine (youout)


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Kidney Topography cont


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The Kidney


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Kidne Perfusion


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Cortical and Juxtamedullary Nephrons


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Filtration (youtube)

Blood pressure

Water and solutes across glomerular capillaries

Reabsorption (youcap)

The removal of water and solutes from the filtrate

Secretion (you2tube)

the tubular fluid

=


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FILTRATION


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water , Na+, Cl- and K+.,

peptides is absorbed.

rox ma u u e ce secre e ac s anbases (HCO3). This secretion is a major

rou e or rugs suc as pen c n.


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.

GFR has to do with how much filtrate is runningdown the tubules er unit of time

Fast filtrate will change reabsorption dymanics of

solutes resent in filtrate GFR is used to find how substances are cleared

from the blood (meds)

Kidney disfunction -Filtration problems go frommild to renal failure (need for dyalisis)


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Renal Blood Glomerular Glomerular Peritubular Peritubular

ow cap arypressure

ra on ra e cap aryPressure

ea sorp on

Afferentconstriction

EfferentConstriction

Afferentdilation

Efferentdilation


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REABSORPTION

Proximal Tubule

Thin loop

Distal tubules

Collecting Duct


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step process 1.

2.

Reabsorption of waterand most particlesdissolved (solutes)

are n e o eabsorption of Na


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Proximal Tubule-ReabsorptionMicroscopic Anatomy


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Basis for Peritubular

Reabsorption Peritubular capillaries provide

nutrients for tubules and retrieve the

fluid the tubules reabsorb.

nco c s grea er an y ros a cP in these capillaries, so thereforeget reabsorption NOT filtration.

Must occur since we filter 180l/day,but only excrete 1-2l/day of urine.

Reabsorb 99% H O 100% lucose

99.5% Na+ and 50% urea. Most ofthis occurs at proximal convolutedtubule.


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amount of water you drink? What creates the transition

between filtration to

Reabsorption ? If a substance is not reabsorbed

what happens to it?

What does secreted mean?


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Countercurrent Multiplier


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e cr ca c arac er s cs w ccreate the countercurrent multiplier:

1. The ascending limb of the loop ofD A

Henle actively transports Na+ and co-

transports Cl- ions out of the lumeninto the interstitium.

2. The ascending limb is impermeableto H2O.

Naa

H2O

H2OX

.permeable to H2O but relativelyimpermeable to NaCl.

. 2 a moves ou o u u e n ointersitium is removed by the bloodvessels called vasa recta thusgra ents are ma nta ne an 2 sreturned to the circulation.



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A: The tubule is initially filled with isotonic fluid

B: Na is pumped out of the ascending loop, raisingthe osmotic pressure outside and lowering itns e. o e a e max mum gra en ns e oout) is 200 mosm/L

C: Water flows out of the descending tubule by,

descending tubule to 400 mosm/L

D: Fresh fluid enters from the glomerulus, pushing

concentrated fluid (400 mosm/L) into theascen ng m

E: In the 2nd round the Na pump produces another200 mosm/L gradient across the membrane, but it

,

the external osmolarity rises to 500 mosm/L.F: The 3rd round of Na pumping raises interstitialconcentration to 700 mosm/L, and so on.

The pumping, osmotic flow and filtration flows areshown as separate activities, but in reality they occur

together as a continuous process.


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formation of


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.

High protein diet = more urea = more.

Kidneys filter, reabsorb and secrete urea.

Urea excretion rises with increasingurinary flow.


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Urea toxic at high

levels, but can be

useful in small

Urea recycling

causes buildup ofg urea ninner medulla.

the osmoticgradient at loop of

en e so 2 canbe reabsorbed.


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-


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Kid F i O i


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Kidne Function Overview

Peritubular capillaries Distaltubule

arteriole

GlomerulusF

R

S

Afferentarteriole

Proximaltubule

Bowmanscapsule

R

R S

R RS

LoopofKEY

Collectingduct

Torenalvein

F

R

SE

en e= Filtration: blood to lumen

= Reabsorption: lumen to blood

= Secretion: blood to lumen

ETo bladder andexternal environment

= Excretion: lumen to externalenvironment


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Clin Nephrol. 1998 Nov;50(5):273-83.

Effect of a ketoacid-aminoacid-su lemented ver low rotein diet on the ro ression of advanced renal disease: areanalysis of the MDRD feasibility study.

Teschan PE, Beck GJ, Dwyer JT, Greene T, Klahr S, Levy AS, Mitch WE, Snetselaar LG, Steinman TI, Walser M.

Vanderbilt University, USA. J Am Soc Nephrol. 1999 Jan;10(1):110-6.

Can renal replacement be deferred by a supplemented very low protein diet?

Walser M, Hill S.

J Nephrol. 2001 Nov-Dec;14(6):433-9.

Low protein diets and outcome of renal patients.

Aparicio M, Chauveau P, Combe C.

Renal Physiology Review-S

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