11 Biology By BISM Academy
17 – Open and closed circulatory system part 2
Closed Circulatory system Earthworm (Pheretima)
Open circulatory system cockroach (Periplaneta)
1. Blood always remain in the blood vessels,
and does not come in direct contact with other cells of the body.
1. Blood does not remain enclosed in the blood vessels and comes in direct contact with other body cells, and bathes them.
2. Inter connected system of arteries, veins, and capillaries present.
2. There are no typical arteries,
veins, and capillaries and for much of the time the blood called haemolymph flows in the cavities or sinuses of body cavity (haemocoel) around the viscera (perivisceral sinus) and around the nerve cord (perineural sinus).
3. Exchange of nutrients and waste products between the blood and tissues via tissue fluid occurs through capillaries.
3. Exchange of nutrients and waste products between the blood and tissues occurs when blood directly bathes the tissues.