Total description about HUMAN WASTE & EXCRETION as well as Removing waste nitrogenous products from body, Information about Nephron.

1. Department of
Pharmacology
Sub :
Pharmacology – 1
Topic: Excretion

2. Contents
• Introduction
• Removing waste nitrogenous products
• Human Excretion
• The nephron
• Reference

3. Excretion

4. • The most important waste product are CO2,
nitrogen compounds, and salts.
• CO2 – produced in cellular respiration (in
addition to water)
• Nitrogen Compounds – (ammonia, urea, and
uric acid) produced by the breakdown of
amino acid (protein digestion)
• Salts – Produced by metabolism

5. Why do we need to excrete Ammonia ?
• All organisms produce ammonia as they
metabolize nutrients (protein digestion)
• Ammonia is a nitrogenous waste that is toxic
and must be removed from the body.
• Particular organism removes ammonia
depends upon where it lives.

6. Removing
Nitrogenous
Waste Products
1. Ammonia (NH3):
o Requires little energy
o Ammonia is highly toxic
o This form of waste can only be used if the
organism lives in an aquatic environment.
o Example: Paramecium, Protists, some ocean
fish

7. (2) Urea:
o Many land animals
and some bony fish
(amphibians,
mammals) dilute
the toxic ammonia
with water.
o This substance is
called Urea & is
filtered out by
kidneys.
o The problem is they
do lose water in the
process!
o Requires Energy

8. (3) Uric Acid
o Not very toxic because
it is insoluble
o Evolved as an
adaptation of land
animals
o Many organisms try to
conserve water &
excrete their nitrogen
waste as a solid
o Examples: insects,
reptiles, birds

10. • Blood enters kidneys from
renel artery
• Blood is filtered by passing
hrough millions of
nephrons
• Wastes pass through ureter
to the bladder as urine
• Clean blood returns to
body through renal vein
• Bladder stores urine and
passes urine out of the
body through the urethra
How does the kidneys work

11. The Nephron
• Nephron has three
functions:
1. Glomerular Filtration :
filter out water, N-
wastes (urea), salt,
glucose, amino acids.
2. Tubular reabsorption
:Reabsorb materials
that the body still
needs (food molecules,
water)
3. Tubular secretions :
collect wastes as urine
and pass them to the
bladder (urea, salts,
other substances)
Blood filters through the kidneys
about 6 times a day.
99% of the water I reabsorbed and
not excreted

12. Nephrons: How the Body makes urine
• Our kidneys are
composed of 1 million
cells called Nephrons
• These long coiled
tubes are where the
blood is actually
filtered and urine is
produced

13. Anatomy of Nephron

15. • http://study.com/academy/lesson/excretion-
definition-examples.html
• (Date: 09/11/2017 Time : 9.09 pm)
• https://byjus.com/biology/excretion-in-
humans/
• (Date: 09/11/2017 Time : 9.17 pm)