Page 2 - LN
P. 2

The circulatory system in humans is composed of three main components, viz. heart,
               blood vessels and blood.




























               BLOOD
               Blood is a type of tissue which is responsible for transportation of substances. Blood

               works as the carrier of various substances.
               Blood is red because it contains a red pigment called haemoglobin.


               Main components of blood:

                   1.  PLASMA: Plasma makes up the liquid part of the blood. It constitutes the largest

                       part of the blood. Plasma is pale yellow, sticky liquid. It is 90% water and 3.5%
                       salt.

                       It contains dissolved substances such as digested food and waste products

                       (like carbon dioxide and urea).
                   2.  BLOOD CELLS: There are two main kinds of blood cells in the human blood, viz.,

                       Red Blood Cells and White Blood Cells.
                          Red Blood Cells or Red Blood Corpuscles (RBC): These are in the shape

                           of discs. They contain a pigment; called haemoglobin. Haemoglobin binds with
   1   2   3   4