Page 106 - Science Class 07

haemoglobin, which helps in transporta on of passes through a closed vessel, aorta only for a
oxygen and nutrients. part of its circula on. For the rest, it flows
through the body cavity. They do not have
haemoglobin in this circula ng fluid. The
circula on fluid of this body is called

haemolymph. Due to lack of oxygen carrying
pigment, they get this par cular func on done
by respiratory tubes.
In other higher animals, a well-developed

circulatory system is present similar to that of
human beings.
Earthworms For example, frogs, lizards, fishes, birds, etc.
The insects such as cockroach, ant, grass-
hopper, etc. have an open circulatory system. It
means blood flows in open space inside their
bodies as they do not have blood vessels. The
blood pumped by a many chambered heart,

Fly Cockroach Ant

1. What is cyclosis?
2. Write the circulatory system of sponges.

3. Write the circulatory system of insects.

4. Name any two animals which have circulatory system like we have.

Circulatory system : An organ system in which oxygen, carbon dioxide and other materials
are transported in the body
Blood : It is sticky fluid present in our body
Plasma : Yellow fluid with 90-92% of water, 6-9% of proteins and 1% of
dissolved substances

RBC : Red blood cells or RBC consist of haemoglobin, a pigment which
transports oxygen
WBC : White blood cells or WBC consist of substances that provide immunity
to the blood
Platelets : Small spherical bodies numbering 3,00,000 per cubic millimetre of blood

Arteries : Blood vessels which carry away oxygenated blood from the heart to
various parts of the body

106 Science-7