Cockroach Circulatory System Short Notes

Cockroach Circulatory System Short Notes

In this article we will discuss about the cockroach circulatory system

Cockroach Circulatory System

  • Cockroach circulatory system is an open type
  • The cockroach circulatory system is poorly developed and consists of haemolymph, haemocoel and heart


  • Circulating fluid does not flow through vessels, rather comes in direct contact with tissues.
  • Haemolymph of cockroach is composed of colourless plasma and numerous types of haemocytes
  • The blood of cockroach is colourless due to the lack of respiratory pigment
  • They do not transport oxygen through the blood
  • Plasma serves transportation of dissolved substances
  • Haemocytes help in phagocytosis and blood clotting


  • Body cavity is filled with blood, thus it is called haemocoel
  • Two diaphragm are present in body cavity
  • They are dorsal diaphragm and ventral diaphragm. These have pores called fenestrae
  • The diaphragm divides the haemocoel into three regions
    1. Dorsal sinus – pericardial sinus has hearts
    2. Middle sinus – perivisceral sinus has alimentary canal and fat body
    3. Ventral sinus – perineural sinus has nerve cord


  • Elongated, contractile lying along the mid dorsal line of thorax and abdomen
  • Cockroach has a 13 chambered tubular heart
  • Heart is differentiated into funnel shaped chambers with ostia on either side. These pores act as valve.
  • 12 pairs of triangular fan-like muscles found in the heart of the cockroach is called alary muscles
  • Alary muscles involved in the role of contraction and relaxation of the heart
  • Blood enters from pericardial sinus to heart through ostia when heart chamber relaxes
  • Each heart chamber pumps blood into anterior chamber when it contracts, and thus blood reaches into head sinus

How Circulatory System Works?

  • Heart pump blood into head sinus through a long tubule called anterior aorta
  • Blood moves from head sinus to perineural sinus
  • Fenestrae help blood flow from perineural sinus to perivisceral sinus
  • Finally blood flows from perivisceral sinus into pericardial sinus
  • In addition contraction of dorsal diaphragm also helps in rapid circulation of haemolymph
  • The rate of heart beat in periplaneta is 49 beats/minutes
  • Blood circulation in cockroach is completed in 5-6 minutes.

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