Facts about Blood

An Overview

Blood is one of the most important components of life. Almost any animal that possesses a circulatory system has blood.

What is blood?

Blood is a fluid connective tissue that consists of plasma, blood cells and platelets. It circulates throughout our body delivering oxygen and nutrients to various cells and tissues. It makes up 8% of our body weight. An average adult possesses around 5-6 litres of blood.

Types of Blood Cells

  • Red blood cells (Erythrocytes)
  • White blood cells (Leucocytes)
  • Blood Platelets (Thrombocytes)

Components Of Blood

There are many cellular structures in the composition of blood. The main components of blood are:

  • Plasma
  • Red blood cells (RBC)
  • White blood cells (WBC)
  • Platelets

Functions of Blood

The blood performs three major functions in the human body, namely:

  1. Transportation
  2. Protection
  3. Regulation of body temperature
  4. Regulation of the pH level of the body.

Here are some interesting facts and information about blood and its functions.

Interesting Facts about Blood


Blood is the only fluid connective tissue that runs throughout the body. It also acts as a means of transport for all the necessary components like nutrients, oxygen, electrolytes, proteins, glucose hormones and other metabolic wastes.


Blood makes up around 7 to 8 per cent of the total body weight. The composition of blood includes two main components – plasma and formed elements or corpuscles, which includes RBCs (Red Blood Cells), WBCs (White Blood Cells) and blood platelets.


The primary functions of blood include transportation, providing protection from foreign invasion and regulation of pH and body temperature.


We, humans, have red-coloured blood, while other species have different colours of blood and this is mainly determined by the respiratory pigment or the protein called haemoglobin.


Blood is mainly composed of RBCs-red blood or erythrocytes, white blood cells (WBCs) or leukocytes, blood platelets or thrombocytes, and plasma that includes protein, salts and water.


WBC –white blood cells, also called leukocytes, play an important role in the human reproductive system by maintaining a healthy immune system, developing a network of blood vessels within the ovary.


A healthy and adult human body comprises approximately 1.325 gallons of blood. A single drop of blood contains millions of red blood cells, thousands of white blood cells and lakhs of blood platelets.


Like other body features, the eye, hair texture and skin colour, blood group is also inherited genetically from our parents. There are 4 main blood groups of human blood – O, A, B and AB and are collectively called the ABO blood group system.


These blood groups are mainly differentiated based on the inherited antigenic substances on the surface of Red Blood Cells.


According to research, the ABO blood group system results in varying nutritional needs and affects the individual’s fertility, personality, stress levels, etc.

There are many more interesting facts and information about blood and its functions. Stay tuned with BYJU’S Biology for more facts and other Biology related topics.


Test your Knowledge on Blood!


Leave a Comment

Your Mobile number and Email id will not be published.