Describe the vascular system of Periplaneta in detail and draw a neat and labeled diagram of it.

Periplaneta has open type of circulatory system. Three main components of circulatory system are:
1. Haemocoel 2. Heart 3. Blood (Haemolymph)
Haemocoel:

• It is a blood-filled cavity.
• It is divided into 3 sinuses by two diaphragms.
• Dorsal or pericardial sinus encloses heart.
• Ventral or perineural sinus encloses nerve cord.
• Middle or perivisceral sinus encloses visceral organs. It is the largest sinus.
• One pair of alary muscles are present in each segment.
• They help in circulation.

Heart:

• Heart is long and tubular.
• It is with 13 chambers - 3 in thorax and 10 in abdomen.
• All chambers are connected to one another through openings.
• The anterior chamber is continued as aorta.
• Each chamber contains ostia.
• Blood enters into the heart through ostia.

Blood:

• Blood is called haemolymph.
• It is colourless.
• It consists of haemocytes & plasma.
• Functions of blood include transport of digested food and excretory wastes. It also helps in the transport of phagocytes to the place of infection and hormones to the target organs.
• The flow of haemolymph occurs in the following pathway:
• Heart $\to$ aorta $\to$ head sinus $\to$perivisceral and sternal sinus $\to$ pericardial sinus $\to$ ostia $\to$heart.