Describe the circulatory system of a cockroach.

(N/A) $\rightarrow$ The blood vascular system of a cockroach is of the open type. This means that during circulation,blood enters into spaces called hemocoel instead of passing through capillaries. Thus,body organs and tissues are in direct contact with the blood.
$\rightarrow$ The blood is mainly composed of blood plasma and hemocytes.
$\rightarrow$ The blood lacks respiratory pigments,so it is colourless. It is called hemolymph. The hemolymph consists of blood plasma and hemocytes.
$\rightarrow$ The heart of a cockroach consists of an elongated muscular tube lying along the mid-dorsal line of the thorax and abdomen. It is differentiated into funnel-shaped chambers with ostia on either side.
$\rightarrow$ The blood cells are of two types: small-sized proleucocytes and large-sized phagocytes. Blood enters the heart from sinuses through ostia and is pumped anteriorly back into the sinuses.