Download MBBS Physiology Presentations 4 Renal Gfr And Rbf Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st Year, 2nd Year, 3rd Year and Final year Physiology 4 Renal Gfr And Rbf PPT-Powerpoint Presentations and lecture notes

Determinants and Regulation of GFR

Learning Objective

To understand -

? The forces that determine glomerular filtration rate.

? The regulation of glomerular filtration

? Autoregulation and its mechanism

? Juxta glomerular apparatus (JGA)
Determinants of GFR

The GFR is determined by

PG

G

Sum of the hydrostatic and

colloid osmotic forces across the

glomerulus ?

P

B

B=0

Starling forces inform us about

net fluid movement:

Determinants of GFR

GFR =Kf x [(P G-P B)-( G- B)]

PG

G

Net filtration pressure

= 10

PB

B
Pressures & causes?Decreased Glomerular Filtration Rate (GFR

GFR =Kf x [(P -P

G )-(

B

G -

c )]

B

REGULATION OF GFR
GFR must be precisely regulated

Intrinsic and Extrinsic Control of GFR

Intrinsic Control mechanisms of GFR

1) Autoregulation

2) Extrinsic Control mechanisms of GFR
Renal Auto regulation - Intrinsic Control

Some concepts regarding control of GFR

(flow in glomerulus)
Some concepts regarding control of GFR

regarding flow of glomerulus

Principle concept : Autoregulation
Renal Auto regulation - Intrinsic Control
a. Myogenic mechanism:

b.Tubulo-glomerular feedback:

a. Myogenic mechanism of Autoregulation
b. Tubulo-glomerular Feedback response

- Juxta Glomerular Apparatus?

N
a
C
l
Tubulo-Glomerular Feedback-TGF ? Apparatus-

(Juxta Glomerulus Apparatus)

NaCl

Sensor: Macula Densa cells ?

Tubulo-Glomerular Feedback-TGF ? Apparatus-

(Juxta Glomerulus Apparatus)

N
a
Cl

Integrator: Juxta-glomerular cells

(JG or Granular cells) ?
Tubulo-Glomerular Feedback-TGF ? Apparatus-

(Juxta Glomerulus Apparatus)

NaCl

Effectors:

Renal Afferent and

Efferent Arterioles

Tubulo-Glomerular Feedback Mechanism
Renin

ACE

Important physiologic functions of Angiotensin II

Arteriolar vasoconstriction

antidiuretic hormone

thirst

aldosterone

NaCl reabsorption

Constrict the glomerular mesangium,
Hormones that Influence Glomerular Filtration Rate

STIMULUS

GFR

Vasoconstrictors

Sympathetic nerves

ECFV

Angiotensin II*

ECFV

Endothelin

Stretch, AII,

bradykinin,

epinephrine, ECFV

Adenosine (AA)

Macula densa NaCl

Vasodilators

Prostaglandins

(PGE1, PGE2, PGI2)

ECFV, shear

Nitric oxide

Stress, AII shear

stress, acetylcholine,

histamine, bradykinin, AT P

Bradykinin

Prostaglandins,

ACE

Natriuretic peptides

(ANP, BNP)

ECFV

These effects of angiotensin I are evident with concentrations that constrict the afferent and efferent arterioles.

ACE, Angiotensin-converting enzyme; AI , angiotensin I ; ANP, atrial natriuretic peptide; ATP, adenosine triphosphate; BNP, brain natriuretic

peptide; ECFV, extracel ular fluid volume; GFR, glomerular filtration rate; PGE, prostaglandin E; PGI2, prostacyclin; RBF, renal blood flow.
Mesangial Cells
Applied

ACE inhibitors (e.g. captopril, enalapril) -

Acute kidney injury (AKI) from NSAIDs

Important points of the lecture

Forces Favoring and opposing glomerular Filtration

1 cause of each PB and PGC
What will happen if GFR is too high or too low?

Efferent arteriole constriction cause increase or decrease in GFR.

What is principle of myogenic autoregulation and range of fluctuation of

MAP for it?

Tubulo-Glomerular Feedback Mechanism

Functions of Angiotensinogen II
Self Assessment

Macula densa cells of DxCT are a

ACE inhibitors are used

type of

in the treatment of

1) Chemoreceptors

2) Osmoreceptors

1) Hemolytic anemia

3) Baroreceptors

2) Hypertension

4) Nociceptors

3) Hyperthyroidism

4) Hydatid cyst

Tubulo-glomerular feedback mechanism is

mediated by:

1) Adrenaline

2) Acetylcholine

3) Adenosine

4) Prostacycline

Thank you