Just as the root center, the muladhara cakra, represents the lement earth, the next-higher one- corresponding to the plexus hypogastricus, which controls the organs of elimination and reproduction-reoresents the element water. It is called sudhisthana cakra.

In the Tibetan systems of meditation this centre is usually not mentioned or regarded as an independent centre, but is combined with the muladhara cakra under the name, the secret place or sacral plexus. This sacral plexus stands for the whole realm of reproductive forces, of sexual as well as of pre-sexual nature, while these functions of the svadhisthana cakra which belong to the negative side of the system of nutrition like disintegration, dissolution and separation of the elements of nutrition into substances which can be accepted and assimilated by the body, and those which can not be assimilated and have to be rejected and eliminated are associated with the next higher centre, the plexus epigastricus or solar plexus.

The centre that corresponds to the solar plexus is called manipura cakra or naval lotus. It represents the element Fire and the forces of transformation, in the physical as wel as in the psychic sense, digestion, assimilation, conversion of inorganic into organic substances as well as the transmutation of organic substances into psychic energies.

The centre that corresponds to the heart is called the Anahata-cakra and represents the element Air. This centre is not necessarily identical with the heart. It regulates and controls the organs of respiration, just as the heart does, and it is said to be situated on the vertical central axis of the body.

The three highest centres are the Throat centre, corresponding to the plexus cervics- the centre between the eyebrows, called ajna cakra, which, according to modern physiology, is said, to correspond to the medulla oblongata-and the crown centre, called sahasrara padma, the Thousand-petalled Lotus, which is associated with the pituitary gland of the Brain.

These last- mentioned highest centres correspond to those forms of akasa which go beyond the gross elements and represent higher dimensions of space, in which finally the quality of light becomes identical with that of space and thereby merges into the psycho-energetic state of prana and into the realm of cosmic consciousness. Just as the two lower centres have been combined into one, so also the two upper centres are regarded as one in the Tibetan system of Yoga. Ajna cakra is therefore not separately mentioned in Tibetan scriptures, but regarded as part of the Thousand-petalled Lotus.

In seven centres of the human body represent in a certain way the elementary structure and dimensionality of the universe, from the state of greatest density and materiality up to the state of immaterial multi-dimensional extension, from the organs of dark, subconscious, but cosmically powerful primordial forces to those of a radiant, enlightened consciousness. That the form-potentialities of the whole universe are latent in these centres, is hinted at by attributing to them all the sounds of the Sanskrit alphabet in the form of seed syllables.

Each of these psycho-physical centres is depicted as a lotus blossom, whose petals correspond to the seed-syllables expressing certain qualities or forces, while the pericarp contains the symbol of the element that governs them, together with its particular seed-syllable. Each of these elementary seed-syllables is associated with a symbolical animal as its vehicle by which the character of the element is expressed. Without going here into further details, like the respective gods and goddess, connected with the centres-which would presuppose a detailed knowledge of the Hindu tantric pantheon.

In order to give readers, trained in western physiology, an easier approach to these specifically Indian teachings concerning the psychic centers, the following definitions of the seven systems of the Human body are as follows.
If we now enumerate the different systems in their sequence, ascending from the basis of the spinal column to the brain, we get the following summary:

The reproductive system, represented by the sacral plexus of the cerebrospinal nerve system, which controls the lower limbs and the external organs of reproduction.

The negative system of nutrition, represented by the prevertebral hypogastric plexus of the sympathetic nerve system, which controls the organs of elimination, bladder, intestines, urinary ducts, and the inner organs of reproduction.
The positive system of nutrition, represented by the prevertebral solar or hypogastric plexus of the sympathetic system, which controls the stomach, intestines, gall-bladder, urinary ducts, seminal ducts, and the gland like organs of the liver, kidneys, spleen, and intestinal glands.

 The system of blood circulation, represented by the heart-plexus of the sympaticus, which controls the heart and the blood-vessels.

The respiratory system, represented by the throat plexus or plexus cervicus of the cerebrospinal system, which, together with the brachial plexus, controls the upper limbs.
The non volitional nerve system, which is represented within the skull by the medulla oblongata, the enlarged continuation of the spinal column, forming the basis of the brain and controlling the special sense-organs, eyes, ears, nose, tongue, skin.

The volitional nerve system, represented by the pituitary gland, a small conical body in the depth of the central great brain tissue, whose physiological function has not yet been discovered. Attention has to be drawn upon the close natural relationship of the pituitary gland with the optical nerves, in connection with a higher interpretation of this organ as an undeveloped base of a consciousness of the seventh order.

The reproductive system expresses the desire for the continuity of consciousness. For the average man this desire is satisfied by the survival of his children, on a higher level of development, however, his physical energy is partially transformed into psychic energy, which finds for itself a corresponding form of expression; and with this twofold fulfillment the majority of men is satisfied. For a growing number, however, it becomes clear nowadays that this system of reproduction hints at the force which may produce the ultimate or spirit man, and that body and soul are only the material from which, by means of transformation, the super-human state will emerge.