CIRCULATORY SYSTEM IN COCKROACH
Type is open or lacunar. i.e. b.v. absent. Organs are dipped in haemolymph.
1. HAEMOLYMPH -
Blood and lymph are mixed. In plasma corpusulses or haemocyte present.
Haemocytes are euqal to W.B.C. and are of 2 types -
(i) Proleucocyte - small nucleus, large in size, produce antibodies.
(ii) Phagocyte - Large nucleus, small in size, engulf harmful bacteria.
In haemolymph Na+ & Cl- present.
In it free amino acids present function as asmotic regulation. Trehalase sugar present.
2. HAEMOCOEL -
True coelome, schizocoelic, filled with haemolymph.
Due to dorsal & ventral porous septa coelome is divided in to three compartments -
(i) Pericardial - heart
(ii) Perivisceral - gut (Largest)
(iii) Perineural - Nerve cord (Smallest)
Coelome is too much degenerated present only in reproductive area & some glands.
By dorsal septa haemolymph flows from perivisceral to pericardial only not vice versa.
By ventral septa haemolymph flows from perineural sinus to perivisceral sinus and vice versa.
Note :- Haemocoel is obliterated. true coelome i.e. flattened dorso-ventrally.
3. HEART -
- Tubular, situated on dorsal side, flow of blood posterior ® anterior, in complete length, made up of 13 chambers (3 thoracic + 10 abdominal).
- First chamber is largest one, open in perivisceral sinus of head sinus. Last chamber is closed at base.
- Between 2 chambers, on lateral side 1 pair fenestrae or ostia present controled by auricular valve, allow haemolymph to enter in to heart chamber not vice-versa. In anterior part of heart chamber ventricular valve present.
- On lateral side of heart 13 pairs allary muscles present which are V-shaped. Pointed end is attached to tergum & flat end to dorsal septa.
Note :- Heart is Neurogenic but in anopheles and some other insects it is myogenic.
4. MECHANISM
- First of all allary muscles are relaxed, volume of pericardial sinus is increased & so pressure is decreased, so blood comes from perineural & perivisceral to pericardial sinus.
- Allary muscles are contracted, volume of pericardial sinus is decreased & pressur is increased, so blood enters into heart's chamber. This time auricular valves are open and ventricular valve are closed.
- Allary muscles are relaxed, volume of pericardial sinus is increased, at the same time blood moves from posterior to anterior in heart and comes in perivisceral sinus of head sinus & to perineural sinus of body. this time ventricular valves are open & auricular valves are closed.
- Perineural sinus supply blood to leg. Perivisceral sinus collect blood from leg.
- Peri visceral sinus supply & collect blood from wings. At the base of wings, legs and antennae pulsating ampullae present.
- Heart beat 49 / minute. Gape between 2 systole is diastasis.