Urine formation

This is the presentation about formation of urine

1. Urine Formation
Dr. Minaxi Parmar
Assistant Professor
Atmiya University

2. Introduction
to Urine
•Urine is a waste
product that is produced
by the kidneys in their
process of cleaning the
blood.
•Urine, a very complex fluid,
is composed of 95% water
and 5% solids

3. Urinary
System
Urinary system
consists of
2 Kidneys
2 Ureters
1 Urinary Bladder
1 Urethra

4. Anatomy of
a Kidney

5. Urine Urine is formed
in the kidney
structure called
the Nephron

6. Nephron
Each kidney
contains over 1
million nephrons
& thousands of
collecting ducts

7. Urine
formation
•Urine is the final product of
the processes of:
• Glomerular filtration
• Tubular reabsorption
• Tubular secretion

8. Filtration
•Filtration of the blood occurs within
the specialized collection of
capillaries in the glomerulus.
•The glomerulus permits water and
small molecules and ions from the
blood to enter a surrounding tubule
called the Bowman’s capsule.
This is called the Glomerular
filtrate.
Blood cells and large protein
molecules remain in the blood and
return to the venous circulation

9. Reabsorption
•Reabsorption of essential chemicals
(glucose, amino acids, NaCl and other
salts, water and vitamins) occurs within
the nephron’s proximal tubule, Loop of
Henle, and distal tubule.
•Reabsorption prevents the loss of
necessary body compounds but also
adjusts the concentration of urine so it
is more dilute when the body has more
water (i.e., hydrated) and more
concentrated when the body is short of
water (i.e., dehydrated).
•If 200 liters of filtrate enter the
nephrons each day, only 1-2 liters of
urine result, obviously most of the
filtrate (99+ %) is reabsorbed.

10. Secretion
•Secretion of chemicals that
the body does not need
(ammonia, drugs, hormones,
toxins) begins in the proximal
tubules and continues in the
distal tubule and the collecting
duct.
•Secretion of excess ions such
as Hydrogen and Potassium
ions help establish electrolyte
and acid-base balance.

11. Urine
•All three processes of filtration,
reabsorption and secretion occur
simultaneously as a result of
complex cellular transport
mechanisms and buffering
mechanisms within the nephron
tubules.
•The glomerular filtrate becomes
more concentrated and acidic after it
leaves the distal tubule and enters
the collecting duct.
•The fluid that leaves the
collecting duct is now urine.

12. Thank you