दोष धातु मल मूलं हि शरीरम् | 

Dosha, Dhatu and Mala are the building blocks of our body and together they carry out all physical and physiological activities in the body.

प्रकृति आरंभकत्वे सति दुष्टि कर्तृत्वं दोषत्वम् |

Factors which are initiating components in defining Individual Constitution and at the same time act as biological forces which have the capacity to vitiate any other substance or body ingredients like Dhatus, Malas and so on are called as Dosha’s.

Dosha is a Sanskrit word derived as; ‘Dushyanti iti Dosha ’ i.e one with the capacity to vitiate other components. These are three in number hence famously known as Tridosha

Dosha’s are further divided into

1. Sharir Dosha which are Vata, Pitta and Kapha
2. Manasik Dosha which are Raja and Tama
   

Vata  वात   - It’s a Sanskrit word derived as 'Va Gatigadhanyoriti Dhatu'  meaning the one which is the initiator of movement and enthusiasm.

Pitta, kapha and other components like Mala and Dhatu are completely dependant on Vata. Vata influence their physiology as well as functions.

Important Functions of Vata-

• It supports all the organs of the body
• It controls each and every movement in the body including respiratory, cardiac and intestinal movements
• It conjugates with the mind and controls all its actions.
• It stimulates all the senses (Indriya) in the body to perform their respective functions
• It’s an originator force behind speech, sense of touch and hearing.
• It’s the source of enthusiasm in the body.
• It stimulates the Agni or digestive power of the body.
• It promotes the process of excretion of waste products from the body.
• It makes the passage into every channel of the body.
• It is responsible for the cell division and even for the formation of child in the womb from the fertilized Ovum.
  

Pitta पित्त - It is a Sanskrit word derived as 'Tap Santape'  which symbolizes heat in the body. Thus all the actions and reactions requiring heat are under influence of Pitta.

Important functions of Pitta

• It stimulates the process of digestion in the body
• It maintains the vision
• It controls the body temperature
• It controls complexion and luster of the skin
• It is the driving force behind physical and mental activities like bravery, pleasure and delight as well as fright, anger and giddiness
• It influences intellect especially the grasping power and recollection of memory.
  

Kapha कफ- Another word for kapha is shleshma. It’s a Sanskrit word derived from ‘Shlish-aalingane’  that is the substance which binds the body substances together.

Important functions of Kapha

• It maintains stability and built up of body
• It gives strength to the body
• It provides required lubrication in joints and keep them strong
• It controls capacity of sexual activity
• It enhances power of retention of knowledge thereby influencing intellect.
•  It has calming effect on mind
  

These are the three Sharir Doshas which get vitiated due to certain specific reasons and have capacity to vitiate the other constituents of the body. They are present in the body right from the birth to death. In fact the percentile presence of Doshas, at the time of conjugation of sperm and ovum remains constant and determines the Prakriti or Individual constitution of the new born.

Though Doshas give rise to diseases in the body when vitiated, they are of immense importance for physical and physiological functioning and maintenance of the body and body systems.

Mansik Dosha’s are i) Raja रज  and ii) Tama तम  their expressions in the body is similar to Rajasik and Tamasik Temperament respectively, which are described while explaining mind.