Download MBBS Physiology Presentations 3 Renal Gfr And Rbf Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st Year, 2nd Year, 3rd Year and Final year Physiology 3 Renal Gfr And Rbf PPT-Powerpoint Presentations and lecture notes

Formation of Urine : Process of Glomerular Filtration

Learning Objective

To understand the function of the filtration membrane

To define glomerular filtration rate, renal blood flow

To measure glomerular filtration rate, renal blood flow
Basic Processes required for Formation of Urine

1. Glomerular filtration-

2. Tubular processing-

a. reabsorption &

b. secretion)

3. Urinary excretion-

.

Site of filtration - Glomerulus
Physiology of Glomerular filtration

Glomerular filtrate
Glomerular ultrafiltrate-protein & cel ular elements free blood

Important contributors:

1. Filtration Membrane (Barrier)

2. Unique pressure dynamics

within the glomeruli

https://www.researchgate.net/publication/285735121_Regulation_of_renal_hemodynamics/figures?lo=1

Glomerular Filtration Membrane / Barrier

1) Endothelial cells layer of the capil ary,

2) Basement membrane and

3) Epithelial cells (podocytes) ? surrounding outer surface of cp

basement membrane.
Glomerular Filtration Barrier ? Cp Endothelial layer

The capillary endothelium has thousands of small holes called

fenestrae

But loaded with negative charged glycoproteins

Glomerular Filtration Barrier - basement membrane

The surrounding basement membrane - is a porous meshwork of

proteins ? contain type IV collagen and proteoglycan fibrillae.
Glomerular Filtration Barrier ? Podocytes Layer

The long finger like processes of the podocytes interdigitate to

cover the basement membrane and are separated by apparent

gaps called filtration slits.

Glomerular Filtration Barrier ? Podocytes Layer
GFB restricts the filtration of substances on the basis of

Size & Electrical charges

Applied - Kidney diseases (Nephropathies) and

Filtration Barrier

Nephrotic syndrome

Glomerulonephritis

Hypertension
2.Unique pressure dynamics within the glomeruli

Dia of afferent arteriole > efferent glom arteriole ?

Capil ary bed between two arteries?

Glomerular Filtration Rate
Glomerular Filtration Rate

120 ml/min

Renal Blood Flow

RBF

1100 ml/min,

RBF is important as -
Renal Clearance/ Renal plasma clearance

10 L

This much volume of fluid

is free of drug in unit time.

Relative clearances of substances
Estimation of GFR by

Renal Plasma Clearance

GFR:

Substance: Inulin

Estimation of RBF by

Renal Plasma Clearance

RBF:

Substance: PAHA
Estimation of GFR? Renal Plasma Clearance

GFR

(C )=U X V / P

in

in

in

Estimation of GFR and RBF ? Renal Plasma Clearance

RBF:
RBF =RPF/0.9 (1-hematocrit)
Estimation of GFR and RBF ? Renal Plasma Clearance

Clinical problem ? TO calculate GFR :

Estimation of GFR and RBF ? Renal Plasma Clearance

Problem-RBF: Calculate RBF of a patient
Filtration Fraction

Filtration Fraction = GFR/RPF=125/625=0.20

20%

Filtration Fraction

Increase in the filtration fraction -

Decrease in the filtration fraction -
Applied Physiology

Glomerular filtration rate (GFR) is an important clinical indicator

of status of kidney function.

Applied Physiology

Serum Creatinine:

normal value =
Significant points in lecture

Filtration barrier, Slit diaphragm, disorder in nephrotic syndrome

Uniqueness of pressure dynamics in glomeruli

GFR, RBF

Substances of measurement and clearance

MCQ

renal clearance of a substance is the VOLUME OF PLASMA from which that
substance is completely removed (cleared) per unit time.Inn that case following is

a false statement:

a) Renal clearance = GFR when No net reabsorption, secretion
b) Renal clearance = GFR when No net reabsorption

c) Renal clearance > GFR Net secretion

d) Renal clearance < GFR Net reabsorption

If a normal person has a plasma creatinine level 1 mg/dl that later

becomes 2 mg/dl, what happens to GFR?

Ans: 50% of the value of GFR at1 mg/dl.
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