________________
104
Preksha Dhyana :
accepted as a member of the endocrine system. It is generally described under "organ of uncertain endocrine function”. However, there cannot be much doubt that it is the source of one or more hormone-like factors.
A lymphoid, two lobed structure, this gland is situated in the chest between the two lungs and extends up into the neck. It descends and comes to the upper portion of the heart. A brownish mass, it reaches its largest size at the begining of puberty, when it is about 5 cms. long, 3.5 cms. wide and 6 mm. thick. and weighs 25-35 gms. It grows rapidly during the first two years of the child's life and it gradually shrinks after the 20th year. By the age of 75 years, it weighs only 6 to 10 gms. Some of the secreting cells, however, remain throughout life. This gland is believed to control the physical growth of children, the greater part of which takes place before the 14th year of age. During this time, it holds other glands, particulary the sex-glands, in check, delays puberty and furthers normal brain development.
The thymus is a lymphoid organ, since it contains closely packed lymphocytes. Besides the function mentioned above, the thymus exerts an influence on the lymph nodes, spleen and other lymphatic tissues so that they too gain the ability to produce lymphocytes and foster the development of immuno-competent cells by means of a hormone. : An interesting correlation that has recently attracted the attention of researchers is the fact that there is a dramatic increase in auto-immune diseases such as arthritis, anemia, (conditions in which the body attacks its own useful cells as a result of errors in recognition mechanism) with increasing age precisely at the time when the thymus is losing its functional capacity.
It is believed that this is the gland that keeps children childish and sometimes makes adults childlike. During childhood, it promotes growth of bones, but at puberty, its functioning begins to decrease, i.e., rise in the functioning level of sex-glands exerts restraining influence on the thymus, but many times the thymus gland does not cease its action. The continuance of its activity after puberty causes peculiar actions of sex-development and stops the process
Jain Education International
For Private & Personal Use Only
www.jainelibrary.org
