1. Biochemistry of kidney and urine

2. Two layers: external – cortex, inner – medulla.2

3. Functional-structural unit – nephron.
Every kidney – about nephrons. 3

4. RENAL FUNCTIONS
Excretion of the end products from the organism (formation of urea)
Maintenance of acidic-base balance
Maintenance of water-salt balance
Maintenance of osmotic pressure
-Hormonal activity
rennin synthesis (blood pressure regulation)
erythropoietin (erythrocytes formation),
1,25-dihydroxycholecalcipherol (vitamin D3)
Regulation of blood pressure
Metabolism of proteins, lipids, carbohydrates, energetic metabolism 4

5. Metabolism in kidneys 80 % of water about 10 % of all oxygen
L of blood/day (25 %)
carbs – main energetic material
Active:
Glycolysis
Ketolysis
Transamination and deamination 5

6. Urine formation Structures responsible for the urine formation:
glomeruli,
proximal canaliculi,
distal canaliculi.
Mechanism of urine formation:
filtration
reabsorption
secretion 6

7. Mechanisms of elimination: filtration reabsorption excretion7

8. Filtration About 120 mL/min or 180 L/day of blood is filtrated.
Takes place in glomeruli.
Substances with molecular mass below 40,000 Da pass through the membrane of glomerulus into capsula.
About 120 mL/min or 180 L/day of blood is filtrated.
Filtration – passive process.
After filtration – primary urine (180 L/day) 8

9. Filtration is caused by:
-hydrostatic pressure of blood in capillaries of glomeruli (70 mm Hg)
-oncotic pressure of blood plasma proteins (30 mm Hg)
-hydrostatic pressure of ultrafiltrate in capsule (20 mm Hg)
70 mm Hg-(30 mm Hg+20 mm Hg)=20 mm Hg
Hydrostatic pressure in glomeruli is determined by the ratio between diameter of ascendant and descendant arteriole 9

10. Reabsorption Takes place in proximal and distal canaliculi.
What is reabsorbed? Glucose (100%), amino acids (93%), water (98%), NaCl (70%) etc.
The urine is concentrated (toxins damages the proximal canaliculi)
Reabsorption:
active
passive.
Lipophilic substances - passive.
Na/K АТP-аse is very active 10

11. Secretion Takes place in proximal and distal canaliculi. Secretion:
Transport of substances from blood into filtrate.
Takes place in proximal and distal canaliculi.
Secretion:
active
passive.
Passive secretion depends on the pH.
What is secreted?
Ions of K, аmmonia, H+
drugs
xenobiotics 11

12. CLEARANCE Clearance = (C urine/C plasma) * V
Clearance of any substance is expressed in ml of blood plasma that is purified from this substance for 1 min while passing through the kidneys.
About 180 L of primary urine is formed for 1 day, about 125 mL of primary urine for 1 min.
Glucose is reabsorbed completely; clearance = 0
Inulin is not reabsorbed absolutely; clearance = 125 mL/min
If clearance is more than 125 mL/min the substance is secreted actively.
Clearance = (C urine/C plasma) * V 12

13. REGULATION OF BLOOD PRESUURE BY KIDNEYS13

14. The increase of blood pressure
REGULATION OF BLOOD PRESSURE BY KIDNEYS
Inadequate supply of blood to kidneys (decrease of blood pressure, hypovolemia)
Constriction of arterioles
Irritation of juxtaglomerular cells
Rhenin
Angitensinogen
Angiotensin І
Angiotensin-converting enzyme
Secretion of aldosteron
Angiotensin ІІ
Reabsorption of Na and water
Vasocostriction
The increase of blood volume
The increase of blood pressure 14

15. REGULATION OF BLOOD PRESSURE BY KIDNEYS
The decrease of blood pressure, hypovolemia
The decrease of blood volume in atriums and carotid sinuses
Reaction of volume-receptors
Impulses to hypothalamus
Stimulation of vasopressine formation
Activation of hyaluronidase in kidneys canaliculi
Depolimeralisation of hyaluronic acid
The increase of water reabsorption
The increase of blood volume
The increase of blood pressure 15

16. MAINTAINING OF ACIDIC-BASE BALANCE BY KIDNEYS
Three mechanisms:
Conversion of two substituted phosphates into one substituted in the cavity of canaliculi
Formation of carbonic acid in the cells with the following dissociation to Н+ and НСО3-
ammonia excretion 16

17. MAINTAINING OF ACIDIC-BASE BALANCE BY KIDNEYS
Cells of canaliculus
Blood
Cavity of canaliculus
Na2HPO4
Na+
Na+
Na+
Na+
HPO42- H+ H+
NaH2PO4 17

18. MAINTAINING OF ACIDIC-BASE BALANCE BY KIDNEYS
Cells of canaliculus
Blood
Cavity of canaliculus
NaHCO3
Na+
Na+
Na+ H+ H+
HCO3-
HCO3-
H2CO3
H2CO3
H2O +
CO2
H2O
CO2 18

19. MAINTAINING OF ACIDIC-BASE BALANCE BY KIDNEYS
Cells of canaliculus
Blood
Cavity of canaliculus
Glutamine
NH3
NH3+H+
Glutamic acid
NH4+ 19