Urine is formed in the kidneys in three stages: ultrafiltration, reabsorption and secretion, and water absorption. In ultrafiltration, blood undergoes filtration through the glomerulus in the Bowman's capsule, forming glomerular filtrate. During reabsorption and secretion, glucose, amino acids, and ions are reabsorbed into the blood while urea, potassium, and hydrogen ions are secreted into the renal tubules. Finally, in water absorption, excess water in the filtrate is absorbed in the collecting duct so that only 1 ml forms urine, while the rest is reabsorbed.

1. WELCOME.....

2. URINE FORMATION

3. Where is urine formed???
As we all know , urine is
formed in kidneys.

4. Urine is formed in three
stages:-
Ultrafiltration.
Reabsorption and
secretion.
Water absorption.

5. Ultrafiltration
 In this step , blood undergoes filtration
through the pores of the Glomerulus in the
Bowman’s capsule.
 The size of the efferent vessel is less than
that of the afferent vessel.

6.  This will lead to the increase of pressure inside the
Glomerulus , resulting in filtration.
 The filtrate is formed and is collected in the capsular
space of the Bowman’s capsule.
 This filtrate is called GLOMERULAR FILTRATE.

7. COMPONENTS OF
GLOMERULAR FILTRATE.
 Glomerular filtrate is similar to that of Plasma.
Water,glucose, amino
acids , ions of
sodium , potassium ,
and calcium ,
vitamins , urea ,uric
acid , creatinine etc…

8. Reabsorption and secretion
The glomerular filtrate
formed is transported to the
COLLECTING DUCT
through the RENAL
TUNULE.

9. During this time,
Glucose , amino acids are reabsorbed
completely into the Peritubular capillaries.
Sodium , Potassium and Calcium ions are
reabsorbed partially into the peritubular
capillaries.
Urea , Potassium , hydrogen ions are
secreted into the Reanl tubules from the
Peritubular capillaries.

10. Water absorption
 Here excess water seen in the Glomerular
Filtrate is absorbed in the Collecting Duct.
 Both the kidneys produce about 127 ml of
GF per minute ,out of which 126 ml is
reabsorbed into the blood. i.e 1 ml forms
urine.
 As a result Glomerular filtrate is changed
into urine.

11.  Later the Urine is transported from the Collecting Duct to
the Ureter through the Pelvis.
 Urine is temporarily stored in the Urinary bladder.
 When the urinary bladder is full , there is a sensation to
urinate and urine is eliminated through the Urethra.
 i.e. MICTURITION process occurs.

12. Components Of Urine
 Water
- 96 %
 Urea
-2%
 Uric acid , Creatinine ,Nacl ,Kcl,
phosphate , Calcium salts etc.
-2 %

13. Do you know???
UROCHROME is the pigment
responsible for the pale yellow colour
of urine.
This urochrome is formed by the
disintegration of Haemoglobin.

14. HOW URINE IS
FORMED?

15. Questions………..
 What is the role of glomerulus in
ultrafiltration?
 Name the pigment responsible for the
yellow colour of urine?
 List out the components of Glomerular
filtrate?
 Define Ultrafiltration?
 Explain about reabsorption and secretion?

16. FOLLOW UP
Draw a neat labelled diagram of
Nepron illustrating the stages in urine
formation?
“Urinating frequency is more in rainy
season than in Summer season “ why?