Yog is integrally linked with the well being of human body. Though it is said that the final aim of yog is to achieve moksh or nirvan, several yogic practices are instrumental in maintaining good health. Real comfort lies in good health and this is an essential component for happiness as well. Those who practise yog as a daily ritual would experience great deal of peace and joy. However, in order to comprehend the health problems relating to human body, preliminary knowledge of anatomy and physiology are necessary. The knowledge of anatomy and physiology forms the basis for the study of biological sciences. Even for a common man, to understand the health problems and to find their solutions, preliminary understanding of this subject will be helpful. At present, the human existence is challenged by the stress disorders or the psychosomatic diseases such as hypertension, hyperacidity, insomnia, heart diseases, diabetes, asthma, etc. To combat these diseases an individual can always resort to yog as it has therapeutic value. It has the potential to tranquilise and balance the mind.


While delving into the history of yog it has been observed that the yogic practises have evolved with passing time with a specific purpose of influencing various psycho-physiological functions. These ancient concepts seem to have been based more on an empirical approach and therefore have less objectivity, when they are compared to the modern scientific concepts which are based on experimental, analytical and objective approaches. The yogi's have arrived at these concepts by introspection, in the form of subjective experiences accompanying various Yogic practices like Asan's, Pranayam etc. which influence different functions of the body. At the same time, they also used the knowledge of anatomy, as recorded in various Ayurvedic texts. A famous treatise on surgical aspects of Ayurveda called Sushrut Samhita mentions specifically that the anatomical description given in that work is not only for the practitioners of Ayurved but is also for the students of Yog.


According to yog the body and mind is never considered as made up of two separate entities. They are rather looked upon as one single composite unit. Similarly the structure of the human body and its function also, are not considered as two separate things but were rather treated as the two aspects of the same organism. There were basic concepts according to which the ancient yogi's comprehended the nature of the human being, its dynamism, and its body structure and function. One of them is the Panch Kosh. A human being is considered existing and carrying out his or her activities simultaneously at five different levels or planes. The term used for these levels is `Kosh`, which literally means the cocoon or the sheath. Panch Kosh, therefore, means the five different levels of existence and operation. A human being is said to exist, simultaneously, on the level of physical body, on the level of physiological-vegetative functions, on the level of emotion and memory, on the level of intellect and on the level of pure consciousness. Through the Yogic practices, such as, Asan's and Pranayam one becomes aware of these different kosh which, in turn, enables man to the correct understanding of one`s own nature.


Pran or life force is responsible for the various functions being carried out within the body. Pranashakti is responsible for the vegetative functions, but at the same time it steers the subtler psychological functions, too. The yogic practices which try to affect Pranic or the vegetative-physiological activities are obviously considered to affect the mind as well and bring about internal awareness. Another element is the Kundalini, the evolutionary energy. According to this concept there is a higher and potentially very dynamic aspect, to this Pranashakti, which in normal circumstances is never called into action. This aspect remains in the dormant state known as `kundalini`. Through the yogic practices when it is stimulated, it is awakened and reaches to its highest possible spiritual potential. Awakening one’s kundalini brings about spiritual enlightenment accompanied by significant psycho-physiological changes.


Besides these, the ancient yogi's also considered the concept of Nadi while comprehending the human anatomy and the impact of yog on it. The Pranashakti which works all over the body, uses some specific channels through which it moves. These channels or passages are known as Nadis. According to the ancient scriptures there is not a single part in the human body which has not been contacted by anyone of these Nadis. In one of the Hath Yog texts it is mentioned that there are three hundred fifty thousand Nadis in the body reaching each and every part of the body. Lastly, the Chakras are six nodal points or centres that are responsible for the different levels of consciousness as well as for the control of various internal organs.


With the passage of time and scientific development the view regarding the structure and function of the body became more objective and more analytical in nature. As per the modern view human body shows a remarkable organisational unity which helps in carrying out all its activities in a coordinated and integrated manner. For the specific function there are different types of cells, evolved specially to carry out that function. These cells when form separate specialised group, it is known as tissue. Different tissues come together to form various organs, and different organs come together to form various systems of the body. The functioning of all these systems collectively contributes in what is called as body function. Thus it is essential to realise that the body function is ultimately a collective function of each and every cell which constitutes the body. The proper functioning of each individual cell, therefore, is the most important factor for the survival of the body as a whole.


There are essentially nine systems that are responsible for structure and function in the human body. The Skeletal system and the Muscular system are the principal systems responsible for the movement. The Nervous system and Endocrine system are principally involved in the organisation and control of the whole body. Respiratory system and Cardiac system are responsible for making the oxygen and nutrients available for the whole body. Digestive system and Excretory system are responsible for making the nutrients available for the body as well as for expelling out the unwanted waste matter from the body. Ultimately the Reproductive system concerns itself with the propagation of the species.


The structure and the function of the body are closely linked with each other. The structure is more defined and is more durable but nonetheless it undergoes changes with the passage of time. On the other hand, the function is more elusive and goes on showing the constant fluctuation. During the growth or decay with a change in the structure, the function changes; similarly in some conditions change in the function can alter the structure as well. This dynamic inter-relationship between structure and function is an important factor in understanding the nature of living organism. One feature that distinguishes human beings from the other beings is their self-consciousness. This is the single most important factor which can influence whole of the human activities. This increases enormously the complexity in the nature of human being too.


These systems in the human body are often affected by a number of diseases. in order to treat them and to keep the body hale and hearty, an individual can always resort to yog. The yogic practices heal the body as well as the mind. Practicing yog can cure, respiratory disorder, digestive disorders, increase blood circulation and ensure proper functioning of the heart. However, according to the different systems a particular yogic practice is suggested. Hence, it is safer to consult a yog practitioner before initiating into this process.


In Vaishnav Laxmi tantra, Hrillekha is said to be the seed mantra of the supreme goddess known variously as Sri Laxmi or Tara. Sri declares Hrillekha the supreme vidya is identified with me. She is my divine, absolute shakti, perpetually endowed with all my attributes.