The Gross or Physical Body - An understanding

Disciple: What are the components of the physical body?
Guru: The physical body is composed of five elements, viz., earth (Prithivi), water (Apah), fire (Tejas), air (Vayu) and space (Akasa).

Disciple: What are the seven primary essences (Sapta-Dhatus) of the physical body?
Guru: Chyle (Rasa), blood (Asra), flesh (Mamsa), fat (Medas), bone (Asthi), marrow (Majja) and semen (Sukla), are the seven primary essences of the physical body.

Disciple: What are the Shad-bhava-vikaras (six modifications of the body) ?
Guru: Asti (existence), Jayate (birth), Vardhate (growth), Viparinamate (change), Apaksheeyate (decay), Vinashyate (death), are the six modifications or changes of the body.

Disciple: What are the links with which the body is connected?
Guru: The body (Deha), action (Karma), love and hate (Raga-dvesha), egoism (Ahamkara), non-discrimination (Aviveka) and ignorance (Ajnana) are the seven links of the chain of Samsara (world-experience). From Ajnana (ignorance), Aviveka is born. Aviveka is non-discrimination between the real and the unreal. From Aviveka is born Ahamkara or egoism; from egoism is born Raga-dvesha (like and dislike); from Raga-dvesha Karma (action) arises; from Karma the body or the Deha is produced. If you want to free yourself from the pain of birth and death, destroy ignorance (Ajnana), the root cause of this Samsara (world-experience), through the attainment of the Knowledge of Brahman or the Absolute. When ignorance is removed, all the other links will be broken by themselves. This physical body of yours is the result of your past actions and is the seat of your enjoyment of pleasure and pain.

Disciple: Why is the body called Sarira or Deha?
Guru: Because the body decays (Sheeryate) on account of old age, it is called Sarira. Because it is cremated or burnt (Dahyate) it is called Deha.

- Guruji Swami Sivananda