A chapter from biology in class nine. It is about kidney that what it is and how it works

1. EXCRETION

2. What is excretion?
Excretion is the process of removing metabolic
waste products and other toxins.

3. What is
metabolism?
Metabolism (from Greek: μεταβολή metabolē, "change") is
the set of life-sustaining chemical transformations within the
cells of living organisms. These enzyme-catalyzed reactions
allow organisms to grow and reproduce, maintain their
structures, and respond to their environments.

4. Raw Materials
(Food and 02)
Useless Materials Useful Materials
Egested (faeces) Metabolised
Metabolic Waste
Products (urea and CO2)
Excreted
Useful Products

5. What are metabolic
wastes?
 carbon dioxide
 water
 ammonia
 urea
 uric acid
These waste products
can damage the cells
as they are mostly
toxic

6. • There are four main excretory organs:
– Lungs
– Colon
– Skin
– Kidneys

7. Kidneys

9. What do the kidneys do?

10. Extracts metabolic wastes from the blood stream and
eliminates it from the body

11. Adjusts blood ph by excretion of more or less acid

12. Adjusts blood salt concentration by excretion of more
or less salt

13. Adjusts blood
volume and
blood
pressure by
secretion of
renin
(a hormone)

14. Stimulates red blood cell production by excretion of
erythropoietin (another hormone)