Ex

  Biology (NTSE/Olympiad)  

3. Transportation

Transportation In Human Being

Transportation In Human Being
In humans, transportation of oxygen O2 nutrients, hormone and other substances to tissue, CO2 to the lungs and waste products to the kidneys is carried out by a well-defined Circulatory System. In lower organisms material is transported by diffusion.
Circulatory System :
It comprises of the heart, blood vessels, blood, lymphatic vessels, lymph, which together serve to transport materials, throughout the body.
Components of the circulatory system in higher animals are -
Blood
Pumping organ- 'Heart'
System of blood vessels for distribution and collection of blood - consisting of arteries, veins and capillaries.

Blood Corpuscles :
I. Red Blood Corpuscles (RBC) or Erythrocytes :
These are minute, circular biconcave discs having no nucleus. They look red due to the presence of red coloured pigment, haemoglobin. Red blood cells have life span about 120 days. They are produced in bone marrow number is 4.5 – 5.5 millon/cu.mm.
Function :
Haemoglobin transports oxygen from lungs to body tissues.
II. WBC or White Blood Cells or Corpuscles :
These are large, nucleated colourless cells and are less numerous than erythrocytes. There are about 5000 W.B.C per mili litre of blood.

WBC are mainly of two Type W.B.C.

III . Blood Platelets :
Platelets are rounded, colourless, biconvex and non-nucleated blood- cells, which help in the coagulation of blood they are called thrombocytes.

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