EXCRETORY SYSTEM


 

·        The Excretory system is a process by which an organism gets rid of waste products of its metabolism.

·         The three system terms excretion, recreation, and egestion all describe the passing or substance from organisms or cells.

·         Removal of  nitrogenous substances like urea, ammonia, uric acid, etc. formed during metabolism from the body of the human is called excretion.

·         Excretory organs are –

1-kidney

2-skin

3-lungs

4-intestin

These are the excretory organs. In which kidney is the main excretory organ and other

Are help in the process of excretion.

·         Excretory materials are-

1-ammonia

2-urea

3-uric acid

 

KIDNEY

 

·         It is a vital part of excretion.

·         In a human being, there exists a pair of the kidney which is dark – red, bean – shaped.

·         Its weight is 140 grams.

·      The   Kidney has about ten lakh structure and functional units, called nephron.

·        A Nephron has three functions:

1-Glomerular filtration of water and solutes from the blood.

2-Tubular reabsorption of water and conserved molecules back into the blood.

3-Tubular secretion of ions and other waste products from surrounding capillaries into the distal tubule.

·         Functions of the kidney:

1-It maintains the PH of blood.

2-It maintains a salt contents of the body.

3-It eliminates toxic substance of the body

4-Kidney secrets  enzyme renin which changes the plasma protein, the angiotensinogen.

 

SKIN

·       The  Oil gland and sweat glands secrete sebum and sweat some other excretory substances to enhance the excretory process.

 

LIVER

·         The cells of the liver transform the excessive amino acid and ammonia of blood into urea which is the main excretory substance .

·         Spleen split the damaged blood cells and separate them from the blood flow.

 

LUNGS

·         CO2 and water vapors and some substances like garlic, onion, and some sices are also excreted by lungs.

 

SOME IMPORTANT POINTS ARE:

 

·         In our urine – water (95% ), urea (2.7% ), minerals (2% ) and uric acid (0.3 % ).

·         The color of urine is yellow because of urochrome.

·         Urochrome made up of diffusion of haemoglobin.

·         The PH of urine is 6.

·       A  Stone  found in the kidney is made up of calcium oxalate.

·         Ammonia is found in urine because it  dissolves in water if an animal lives in water.

·         The animal which secretes uric acid which lives in lack of water (dry condition).

Ex-birds and insects, lizards, and snakes.

·         The animal which lives in- between land and water which secretes urea.

·         How to made urea- protein à amino acid à NH3  +  CO2  à Urea (liver) à blood (kidney).

·       The  Secretion of NH3 is called  ammonotelic animal.

·        The Secretion of urea is called  ureotelic animal.

·         The Secretion of uric is called  uricotelic animal.

Various animals and their excretory organ:

Animal

 

Excretory organ

Unicellular animal

Diffusion /osmosis

coelenterates

Direct by cells

Platyhelminthes

Flame cells

ascehehelmimthes

Renette cells

annelida

nephridia

Porifera

Canal system