Renal Physiology lecture 1

1. Dr./ Hussein F. Sakr
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Renal Physiology

2. Anatomy of the kidney
• The kidney is a retroperitoneal
organ, about 150 gm in weight
(2 kidneys  0.5 % of the body
weight).
• It is covered by a renal capsule
and renal fascia.
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3. Structure of the kidney
• The kidney is divided into an outer cortex and
inner medulla.
- The medulla is composed of renal pyramids,
separated by renal columns.
- The renal pyramids empty urine into the
calyces that drain into the renal pelvis. From
there urine flows into the ureter and is
transported to the bladder to be stored.
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4. General function of the kidney
• Regulate ECF volume.
• Regulation of electrolytes.
• Regulation of arterial blood pressure.
• Regulation of pH (acid-base balance).
• Excretion of waste products.
• Endocrinal function (renin- erythropoietin- active vitamin D).
• Degradation of hormones.
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5. Functional organization of the kidney
• Renal cortex:
Red and dotted.
Contains glomeruli.
Contains proximal tubules,
distal convoluted tubules and
cortical collecting duct.
• Renal medulla:
Pale and radial.
Contains renal pyramids which
contain minor calyces that unite
to form major calyces.
Contains loop of Henle and
medulary collecting ducts.
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7. Blood supply of the kidney
• The kidneys receives its blood
through the renal artery.
• The renal artery is divided into
anterior and posterior branches
 each one divides into 5
segmental branches interlobar
 arcuate  interlobular 
afferent  glomerular
capillaries  efferent arteriole.
• Efferent arteriole  peritubular
capillary and vasa recta 
interlobular vein  interlobar
vein  segmental  renal vein
 IVC.
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10. Nephron
it is the structural and functional unit of the kidney
Renal corpuscle
• Formed of:
1) glomerulus: 20-40 loop of
capillaries between afferent
and efferent arteriole.
2) Bowman’s capsule: which is
the blind end of the proximal
tubule.
Renal tubules
• Formed of:
1) Proximal tubule.
2) Intermediate tubule (loop of
Henle).
3) Distal tubule (distal
convoluted tubule, connecting
tubule and collecting duct.
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13. Types of nephrons
Superficial cortical
• 85-90 % .
• Glomerulus in the outer 2/3 of the
cortex.
• Loop of Henle is formed of DLH
and ALH.
• Loop of Henle makes a bend at the
junction between outer and inner
medulla.
• Small in size with low capacity to
reabsorb salt and water.
Juxta medullary
• 10-15 %.
• Glomerulus in the inner 1/3 of the
cortex.
• Loop of Henle is formed of DLH ,
thin ALH and thick ALH.
• Loop of Henle makes a bend at the
tip of inner medulla.
• Large in size with high capacity to
reabsorb Na and water.
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14. Types of nephrons
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15. Juxta-glomerular apperatus
• It is system formed of modified:
1) Macula densa cells.
2) Juxta- glomerular granular
cells.
3) Extra-glomerular mesengial
cells.
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16. Macula densa cells
• Modified tubular epithelial cells.
• Present at the transitional zone between thick ALH and DCT.
• Monitor Na and chloride concentration in the tubular fluid.
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17. Juxta glomerular granular cells
• Present in the wall of the afferent arteriole.
• Smooth muscles with epitheliod apperance.
• Forms , stores and secretes renin.
• Contains B1 adrenergic receptors.
• Acts also as baroreceptors.
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18. Extraglomerular mesengial cells
• It is a continuation of the intraglomerular mesengial cells.
• It is in direct contact with the macula densa and juxtaglomerular
granular cells.
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19. Stimuli for renin release
• Sympathetic stimulation.
• Renal ischemia.
• Decrease Na+ and Cl- concentration in the tubular fluid.
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20. Mechanisms of stimulation:
Renin release
In cases of hemorrhage with
decreased circulating blood
volume  stimulation of low
and high pressure
baroreceptors located in the
great vessels of the thorax
 stimulation of the
sympathetic nervous system
 stimulation of B receptors
on JGG cells  renin
release
With renal artery stenosis or
thrombosis  decreased
renal perfusion pressure 
stimulation of the juxta
glomerular granular cells 
renin release.
Decreases Na & Cl
concentration of the tubular
fluid  stimulation of the
macula densa that
stimulates the JGGcells via
Prostaglandins  renin
release.
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21. Renin Angiotensin Aldosterone system
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22. Inhibitors of renin release
• Aldosterone .
• Atrial Nariuretic Peptide (ANP).
• AII.
• Hypernatremia.
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23. Function of the renin angiotensin system
Salt and water retention
1- angitensin II increases Na
reabsorption from proximal
tubules.
2- AII stimulates the zona
glomerulosa of the adrenal
cortex to secrete aldoseterone
that increases Na reabsorption
from distal tubules.
Vasoconstriction
1- arteriolar constriction
increasing the afterload (arterial
blood pressure).
2- Venoconstriction increasing the
preload (venous return).
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24. Pharmacological Inhibitors of the RAAS
• Angiotensin converting enzyme inhibitors: decreased the formation of
AII.
• Angiotensin II blockers: decreased aldosterone release.
• B- blockers.
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