1. kidney

2. kidney

3. Physiological control of GFR & Renal Blood Flow
Sympathetic Nervous System
Hormonal and Autacoid control
Feedback controls intrinsic to the kidney
kidney

4. Sympathetic Nervous System
kidney.lecture 5b
28 May 2019
Sympathetic Nervous System
Stimulation: ↓ GFR & ↓ Blood Flow
Moderate/ Mild Stimulation: Little Effect
kidney
dr.rashid mahmood

5. Hormonal Control Catecholamine's: GFR
Angiotensin II : Prevents decrease in GFR
B.P
Blood volume
Salt intake.
Atrial Natriuretic peptide: GFR
kidney

6. Autacoids Endothelin: ↓ GFR Blood vessel damage Toxemia of pregnancy
kidney.lecture 5b
28 May 2019
Endothelin: ↓ GFR
Blood vessel damage
Toxemia of pregnancy
Renal failure
Endothelial Derived Nitric Factor: ↑ GFR
Normally present in small amounts (vasodilator)
May ↓ in some abnormal conditions → ↓ GFR
Prostaglandins (PGE2 and PGI2): ↑ GFR
(drugs that block prostaglandin e.g. NSAID can cause ↓ GFR)
Bradykinin →↑ GFR
Autacoids are biological factors that are primarily characterized by the effect they have upon smooth muscle. With respect to vascular smooth muscle, there are both vasoconstrictor and vasodilator autacoids. Vasodilator autacoids can be released during periods of exercise. Their main effect is seen in the skin, allowing for heat loss. The word Autacoids comes from the greek "Autos" (self) and "Acos" (drug). These are local hormones, therefore have a paracrine effect. Some notable autacoids are: eicosanoids, angiotensin, neurotensin, NO (nitric oxide), kinins, histamine, serotonin, endothelins, etc.
kidney
dr.rashid mahmood

7. Function of blood flow autoregulation
Other Tissues and kidney
Delivery of OXYGEN at normal level
Delivery of NUTRIENTS at normal level
Remove WASTE Products of metabolism
Despite changes in Arterial pressure.
In Kidney
Maintains a relatively constant GFR
Precise control of excretion of water and solutes
kidney

8. Autoregulation of GFR & Renal Blood Flow
kidney.lecture 5b
28 May 2019
Autoregulation of GFR & Renal Blood Flow
These
mechanisms
Still function in
Blood-perfused
kidneys
That have
Been
removed
from the
body,
independent
of systemic
influences
dr.rashid mahmood

9. 25% ↑in BP 100 mmHg to 125 mmHg If no autoregulation
25% ↑ in GFR= 225 L/day
Tubular reabsorption= L/Day
Urine output= 46.5 L/Day
In reality, much less effect on urinary volume due to
kidney

10. Autoregulation of GFR & Renal Blood Flow
1.Tubulo-Glomerular Feedback
2. Glomerulo-Tubular Balance
3. Myogenic autoregulation.
kidney

11. Tubulo-Glomerular Feedback
kidney.lecture 5b
28 May 2019
Tubulo-Glomerular Feedback
JuxtaGlomerular Complex=
JuxtaGlomerular Cells+
Macula Densa
kidney
dr.rashid mahmood

12. Tubulo glomerular Feedback Mechanism
TWO Componenets
Afferent arteriolar feedback mechanism
Efferent arteriolar feedback mechanism
kidney

13. kidney

14. Flow rate
kidney

15. Glomerulo -Tubular Balance
↑ Filtration → ↑ Reabsorption
Second line of defense to buffer the effects of spontaneous changes in GFR on urine output.
kidney

16. Myogenic Autoregulation
kidney.lecture 5b
28 May 2019
Myogenic Autoregulation
Stretch → Contraction (resist stretching)
Mechanism: stretch → ↑ Ca++ entry into muscle cells → muscle contraction
Advantages:
Prevent overstretch of vessel wall
Prevent ↑ in GFR
Less important
kidney
dr.rashid mahmood

17. kidney