What is Blood made up of ? Various Components of Blood and Functions

Blood

Blood is a liquid connective tissue.  It is circulated throughout the body by the pumping action of heart. Blood is essentially an aqueous solution containing electrolytes, organic molecules, having suspended particles.

Red Blood cells (RBC; erythrocytes)
White Blood cells (WBC; leukocytes)
Blood plasma the solution part of the blood ( blood minus the particles.)
Blood Serum when a protein called fibrinogen is removed from the plasma, blood serum is obtained.

Major components of blood and their main functions are given below:

Functions of Blood

The main functions of blood are:

Blood is the vehicle for metabolic communication between the organs of the body.

Blood transports nutrients from small intestine to the liver and other organs. It also transports waste products to the kidneys for excretion.

Blood transports oxygen from the lungs to the tissues and CO2 generated during the respiratory metabolism to lungs for excretion.

Role of Blood in Oxygen Transport

Respiration is a process in which oxygen gas (as air) is inhaled and the carbon dioxide is exhaled. Blood transports these gaseous compounds through hemoglobin present in red blood cells (RBC).Hemoglobin is a globular protein. In lungs, where oxygen is present in higher concentrations, hemoglobin combines with oxygen to form oxyhaemoglobin. In tissues where oxygen content is low, oxygaemoglobin  dissociates releases oxygen for use in respiration reaction.

Blood Vessels

There are three types of blood vessels in our body:

1. Veins 
2. Arteries
3. Capillaries

 Veins

Veins are tube-like blood vessels situated just under the skin. These can be easily seen as greenish -blue tubes on your hands and legs. Veins carry carbon dioxide rich blood from different parts of our body to the heart. There are valves present in veins which allow blood to flow only in one direction.

Arteries

Arteries carry the oxygen rich blood from the heart to all parts of the body. Arteries are elastic, thick walled and are deeper under the skin. Blood flow through arteries is rapid and under pressure. 

Capillaries

There is a network of capillaries in our body. Capillaries are very thin. Capillaries connect veins and arteries.