Blood is a red coloured fluid flowing through the heart and blood vessels.it is also sometimes called as river of life because it circulates all the essential nutrients and oxygen to our body.it is made up of liquid part plasma( water and salts) and solid part( RBC and platelets).blood is pumped by heart to our whole body. Blood is a component of circulatory system of our body.
Structure of blood
Blood is formed mainly of two components that are Plasma and blood cells .plasma is a pale yellow fluid part of our blood .it is about 55 % of our blood composition. Blood cells is also called blood corpuscles. they constitutes about 45% of blood. it is of 3 types that is RBC ( Red blood cells) or erythrocytes , WBC(White blood cells) or leucocytes and blood platelets or thrombocytes.
Some Characteristics of blood
- Blood is heavier and thicker than water
- its pH lies between 7.3 to 7.4.
- Blood’s volume in our body is about 5 to 6 litres.
- It is saltish in tastes
Functions of blood:-
- Transportation of gases : The blood carries oxygen from the lungs to the tissues and carbon dioxide from tissues to the lungs.
- Transport of food :- It carries digested food like amino acid , glucose and many other s from our intestine to different organs of the body.
- Temperature regulation :-It absorbs heat produced by respiration in internal tissues and transport it in to the skin and lungs for dissipation.
- Distribution of hormones :- The endocrine glands secrete hormones directly into the blood . Blood helps to transport them in required organs.
- Defence against diseases :- It produces certain antibodies which fights against bacteria. white blood cell (WBC) covers the disease causing bacteria and protect the body.
Blood groups in humans
Karl Landsteiner discovered that human beings have glycoproteins on the surface of RBC called antigens. and globulin proteins in the blood plasma called antibodies. therefore, there is 2 types of antigens A and B and two types of antibodies antibody a and antibody b in our body. Based on this concept , there are 4 types of blood groups found in human body.
- ABO blood groups
- person with antigen A are said to be having blood group A.
- person with antigen B are said to be having blood group B.
- persons having both antigen A and antigen B are said to be having blood group AB.
- Person with no antigen is said to be having blood group O.
- during blood transfusion , we cannot mix two different types of blood group in a body. when blood groups of 2 different types of groups A and B is mixed , clumping reaction occurs. because either the antibodies of recipient ‘s blood destroys the RBC of donor blood or vice versa.
Person with blood group A are called universal donor , because they can donate blood to any of the blood group. while person with blood group AB are called universal recipients because they have no antibodies and can receive blood from any of the blood group.
2.Rh factor ( Rhesus antigen system) : – Human blood also have Rh antigen . it is of two types Rh positive and Rh negative. Transfusion of Rh negative with Rh negative can be done with no problem and same goes for Rh positive to R h positive transfusion.( Source : Veer Bala Rastogi , 96).