11. Study of Animal Type - Cockroach- part 04 - Respiratory system

 

11. Study of Animal Type - Cockroach- part 04 - Respiratory system


Respiratory system or tracheal system :

  • Cockroach has an internal respiratory system of air tubes called tracheal system, by which air is brought into the body and is in contact with every part of body. 
  • It allows exchange of gases directly between the air and tissues without the need of blood.


Spiracles : 


  • Spiracles are respiratory openings.
  • They are paired, present on ventro-lateral side of body, in pleural membrane. 
  • Cockroaches have two pairs of thoracic and eight pairs of abdominal spiracles. 
  • The spiracles open into a series of air sacs from which the tubes called trachea arise.

Trachea : 

  • The trachea form a definite pattern of branching tubes arranged transversely as well as longitudinally. 
  • They are about 1mm thick and have spiral or annular thickening of chitin.
  • The inner lining of chitin prevents the trachea from collapsing. 
  • Each trachea branches into number of smaller tubes called tracheoles.

Tracheole : 

  • These are fine intracellular tubes that penetrate deep into tissues. 
  • They are thin and not lined with chitin. 
  • They end blindly in the cells. 
  • Each tracheole at the blind end is filled with a watery fluid through which exchange of gases takes place. 
  • The content of this fluid keeps changing.
  •  At high muscular activity, a part of fluid is drawn into the tissues to enable more and rapid oxygen intake. 
  • The rhythmic movements of thoracic and abdominal muscles renew the air in the tracheal system. 
  • The body fluid does not distribute the gases but simply acts as a stationary medium for diffusion.

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