CIRCULATORY SYSTEM OF MAN
, In unicellular organisms, the body cell is
exposed to environment hence there is no need
of circulation. In these organisms oxygen,
carbon-dioxide, waste materials etc are moved
by diffusion. But in multicellular organisms
where all the body cells are not in direct
contact of surroundings there is need of
circulatory system for transportation of
necessary materials and removal of waste
products.
,Functions of circulatory system:
The circulatory system performs
following functions in an animal body
i) Transport of nutrients,
ii) Transport of waste products,
iii) Transport of respiratory gases,
iv) Transport of chemical messengers,
v) Maintenance of pH,
vi) Temperature regulation etc.
, Types of circulatory system:
i) Open circulatory system:
In open circulatory system blood flows through large
open spaces and channels called sinuses and lacunae
among the tissues. Tissues are in direct contact with
the blood e.g. most arthropods, prawns, insects etc.
ii) Closed circulatory system:
In closed circulatory system, blood flows through a
closed system of chambers called heart and blood
vessels. Blood does not come in direct contact with
the tissues e.g. Echinoderms, Annelids and all
vertebrates.
, In unicellular organisms, the body cell is
exposed to environment hence there is no need
of circulation. In these organisms oxygen,
carbon-dioxide, waste materials etc are moved
by diffusion. But in multicellular organisms
where all the body cells are not in direct
contact of surroundings there is need of
circulatory system for transportation of
necessary materials and removal of waste
products.
,Functions of circulatory system:
The circulatory system performs
following functions in an animal body
i) Transport of nutrients,
ii) Transport of waste products,
iii) Transport of respiratory gases,
iv) Transport of chemical messengers,
v) Maintenance of pH,
vi) Temperature regulation etc.
, Types of circulatory system:
i) Open circulatory system:
In open circulatory system blood flows through large
open spaces and channels called sinuses and lacunae
among the tissues. Tissues are in direct contact with
the blood e.g. most arthropods, prawns, insects etc.
ii) Closed circulatory system:
In closed circulatory system, blood flows through a
closed system of chambers called heart and blood
vessels. Blood does not come in direct contact with
the tissues e.g. Echinoderms, Annelids and all
vertebrates.
