Thymus Gland – Class 11 | Chapter – 22 | Biology Short Notes Series PDF

Thymus Gland: The thymus is a very unique organ that is at its largest in children and shrinks away as the body grows older. It is about 2.5 to 5 cms wide, 4 to 6 cms long and 1 cm thick at birth. At its largest instance, (viz. during puberty) the thymus weighs just under 30 grams. After puberty, the thymus slowly starts to shrink and by the age of 75, it is nothing more than fatty tissue.

Location of Thymus Gland

The thymus is located in the anterior part of the chest, right behind the breastbone (or the sternum) and between the lungs. It has a pinkish-grey complexion and is lobed, with primary two lobes and smaller lobes radiating from within. The two lobes may be separated or united and generally vary in size.

Thymus Gland

Functions of Thymus Gland

One of the most important functions of the thymus is to stimulate the production of very specialized cells called T-cells (also called T-lymphocytes). These cells are responsible for directly fending off foreign pathogens such as viruses and bacteria. They also regulate the immune system, helping to prevent autoimmunity, wherein, the body’s immune system elicits immune responses on its own healthy cells. Thymus also secretes thymosin to stimulate the development of T-cells.

Disorders of Thymus Gland

The most common disorders caused by the dysfunctioning of thymus gland are- Myasthenia gravis, pure red cell aplasia, and hypogammaglobulinemia.

Myasthenia gravis is caused due to abnormal enlargement of the thymus. The enlarged thymus produces antibodies that destroy the muscle receptor sites. Thus the muscles become very weak.

Pure red aplasia is caused when the patient’s own immune cells attack the blood-forming stem cells. This happens when there is a tumour in the thymus.

Hypogammaglobulinemia occurs when the body does not produce enough antibodies.

Harmons of Thymus Gland

The thymus releases a hormone called thymosin which helps kickstart the production of T-cells. Throughout childhood, lymphocytes, a type of white blood cells are known to pass through the thymus, wherein they are ultimately changed into T-cells.

As T-cells attain maturity, they move towards the lymph nodes, which are clusters of immune cells distributed all over the body. However, regardless of where they are located, these T-cells can sometimes develop into cancerous tumours, and the condition is known as Hodgkin disease. These cells are called non-Hodgkin lymphomas.

Thus the most significant thymus function is its role in protecting the body from all sorts of diseases and ensuring its long-term health. The dysfunction of the gland can cause major diseases, for instance, red cell aplasia, myasthenia gravis and hypogammaglobulinemia.

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By Team Learning Mantras