Excretory system

1. Human Excretory
System
Prof. GHIZAL FATIMA,
ERA UNIVERSITY,
LUCKNOW,
INDIA

2. Excretory System
Excretion – removes cellular waste
The process that collects & removes
harmful or useless substances that
form in the body or are taken into the
body from the blood, tissues, and cells.

3. Excretory System
Although the urinary system has a major role in
excretion, other organs contribute to the excretory
function.

4. Four Organs of the Excretory System
•The lungs in the respiratory system excrete some
waste products, such as carbon dioxide and water.
•The skin is another excretory organ that rids the
body of wastes through the sweat glands.
•The liver (via the intestines) excretes bile pigments
that result from the destruction of hemoglobin. It
also converts nitrogenous waste from the break
down of proteins into urea.
•The major task of excretion still belongs to the
kidneys, the major organ in the urinary system. If it
fails the other organs cannot take over and
compensate adequately.

5. 1- Filtration: The excretory tubule collects filtrate from the
blood. Water and solutes are forced by blood pressure across
the selectively permeable membranes of a cluster of capillaries
and into the excretory tubule.
2. Reabsorption: The transport valuable
substances from the filtrate and returns them.
3. Secretion: Other substances are extracted from body fluids
and added to the contents of the excretory tube.
4. Excretion: The filtrate leaves the system and the body.

6. Cellular Waste
Heat
Water
Salts
CO2
Urea
W/O excretion poisonous wastes build
up in blood, cells, and tissues.
Could lead to serious illness &
eventually DEATH!

7. Liver – Some Functions
Functions in Excretion
–Detoxifies Blood
Filters Bacteria, alcohol, drugs, toxic
substances
Changes them into inactive or less toxic
forms.
 Excretes Bile
 Contains
 Worn-out RBC
 Bile salts
 Cholesterol

8. Liver Produces UreaFunctions in Excretion
–Forms Urea
• Changes toxic wastes (ammonia – from break
down of amino acids) to Urea.
• Urea  Blood  Kidneys
• Filtered out & excreted in Urine

9. Lungs –Main Function
Alveoli - Exchange O2 & CO2 between air and
blood (through process of diffusion)
Lungs excrete CO2 when you EXHALE

10. Skin
• Sweat Glands
– Help cool body: Heat escapes through
millions of pores in skin surface
– Excrete perspiration (evap. cooling)
• 99% H2O
• Mineral Salts
• Urea

11. Kidneys & Urinary System
• Urinary System – excretes waste and
maintains homeostasis of body fluids.
– Kidneys (main organ of the system)
– Ureters
– Bladder
– Urethra

12. Kidneys & Urinary System
• Kidneys
– Two
– Fist sized
– Bean shaped

13. Kidneys- Functional Units & Product
Nephron (about one million per kidney)
– Microscopic units that filter blood of wastes.
– H2O and waste taken from blood into nephron
Form URINE
 Glomerulus (clump of capillaries)
 At end of each nephron
 Network of coiled tubes – diffusion of wastes -
while useful substances & water are reabsorbed
 Urine
 Pale yellow solution
 Urea, H20, salts, other trace solutions (toxins…)

14. Urinary System - continued
Ureters
– Narrow muscular tubes
– Connect Kidney  Bladder
 Bladder
 Muscular sac
 Stores Urine
 Expand to fill
 Muscle relaxes
 Urine squeezed into Urethra

15. Urinary System - endpoint
Urethra
– Tube leading from Bladder  outside of body

16. Glomerulus
Renal Tubules
Renal Pelvis
Renal Calices
Ureters
Flow of Urine

17. Failures of Homeostasis
• Bladder & Kidney Infections caused by
bacteria from colon/rectum entering urethra.
• Kidney Stones - crystallization of mineral salts
& uric acid that block passage of urine
• Kidney Disease - caused by long term
diabetes, infections, & chemical poisoning
• Gout – form of arthritis where excess
production of uric acid leads to deposits of
crystals in joints (esp. toes)