Blood consists of two parts - a liquid part and a cellular part. Name these parts and briefly describe them.

Blood is a red coloured fluid which consists of two parts:

1. Liquid part — The liquid part of the blood is called Plasma. Plasma is yellow in colour. 90% of Plasma is water and the remaining 10% consists of dissolved proteins, nutrients, waste product and hormones.
2. Cellular part — The cellular part of the blood is called Corpuscles. The corpuscles are of three types:
   
   1. Red Blood Cells (RBCs) — RBCs are also called as Erythrocytes. They carry oxygen from lungs to all the body tissues and cells and remove carbon dioxide produced in the cells and carry it back to the lungs. RBCs are circular or biconcave disc shaped. A mature RBC does not contain nucleus. Haemoglobin present in RBCs helps in transport of oxygen and gives them the red colour.
   2. White Blood Cells (WBCs) — WBCs are also called Leukocytes. They are colourless and lack haemoglobin. They are larger than RBCs and have a distinct oval or lobed nucleus. WBCs provide immunity by destroying the disease causing germs and producing antibodies
   3. Platelets — The platelets are also called Thrombocytes. They are round in shaped and the smallest in size. They help in the clotting of blood which prevents excessive blood loss and direct entry of disease causing germs into the blood through cuts and wounds.