How Does the Thymus Support Your Immune System?
The thymus, a primary lymphoid organ, is a key component of our immune system. It functions as the site of T cell maturation and development. It is active only till puberty and starts to slowly shrink and get replaced by fat. Though it is little-known and not active post-puberty, yet, it plays a very vital role in protecting us against autoimmune disorders. Autoimmunity is the condition which occurs when our immune system goes rogue and starts destroying itself.
The following section will shed light on thymus and thymus function.
Thymus Gland Location
The thymus is a soft, bilobed structure and is encased between the chest, the breastbone or sternum and between the lungs. To be precise, the thymus lies encapsulated in the superior mediastinum and the anterior region of the inferior mediastinum, next to the pericardium of the heart. Also, this is almost anterior to the heart vessels, and somewhat deep inside the sternum.
The phrenic nerves, which connect and supply to the diaphragm, lie parallel to the left and right side of the thymus. The two different lobes of the thymus are connected in the middle with the help of the isthmus.
While the thymus is functional in infants, it is redundant in adult humans. As a child slowly approaches puberty, the thymus starts to shrink and eventually, replaced by fat. Surprisingly, in adults, the thymus weighs only about 5 grams.
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Read on to find out more about thymus function.
Thymus Gland Function
As mentioned above, the thymus is the site of development of progenitor cells, which are the precursors of mature T-cells (cells derived from the thymus). Our body employs these T-cells to help locate and destroy cells that are infected, cancerous or prone to disease. These mature T-cells also provide a safe space to other organs of the immune system to gain nourishment and grow.
Furthermore, the T-cells help fend off foreign disease-causing pathogens such as deadly viruses and bacteria. Thus, the thymus helps to regulate the immune system and prevent autoimmunity in the body.
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Rack Your Brains: Now that you know how the thymus works, it’s time to find out how to test thymus function. Consult your teacher, mentor or a school senior and conduct experiments to know how it works.
Pop Quiz 1
Which of these are cells produced by the thymus?
A-cells
B-cells
C-cells
T-cells
Thymus Gland Hormones
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.
This was all about thymus definition and function. For more on the endocrine system and its various glands, sign up for live demo classes and watch them for free on our Vedantu app.
FAQs on Thymus: Functions, Location & Importance
1. What is the thymus gland and where is it located in the human body?
The thymus is a primary lymphoid organ essential for the proper development of the immune system. It is a bilobed (two-lobed) structure located in the upper part of the chest, in the mediastinum, situated between the lungs and just behind the sternum (breastbone). It lies superior to and partially in front of the heart and aorta.
2. What are the main functions of the thymus gland for a Biology student?
The primary function of the thymus is the maturation and selection of T-lymphocytes (T-cells), a crucial type of white blood cell. Its key roles include:
- T-Cell Maturation: It provides a specialized environment for immature T-cells, which originate in the bone marrow, to mature into functional immune cells.
- Development of Immunological Self-Tolerance: The thymus 'trains' T-cells to distinguish between the body's own cells ('self') and foreign invaders ('non-self'), preventing autoimmune reactions.
- Hormone Production: It secretes hormones like thymosins, which stimulate the development and differentiation of T-cells.
3. What hormones are produced by the thymus, and what is their role?
The thymus gland produces a group of peptide hormones collectively known as thymosins. The main function of these hormones is to promote the proliferation and differentiation of T-lymphocytes. By doing so, they play a critical role in establishing and maintaining cell-mediated immunity, which is the body's defence mechanism against pathogens that replicate inside cells, such as viruses.
4. Why does the thymus gland shrink with age, and what is this process called?
The thymus gland undergoes a natural process of shrinking with age called thymic involution. It is largest and most active during infancy and puberty. After puberty, the gland gradually atrophies, and its functional tissue is slowly replaced by adipose (fat) tissue. This occurs because the body has already produced a diverse and long-lasting pool of T-cells during the early years, reducing the need for new T-cell production in adulthood.
5. How does the thymus differ from secondary lymphoid organs like the spleen or lymph nodes?
The key difference lies in their function and stage of lymphocyte development. The thymus is a primary lymphoid organ where lymphocytes mature and become immunocompetent (able to mount an immune response). In contrast, the spleen and lymph nodes are secondary lymphoid organs. They are the sites where mature lymphocytes are activated, interact with antigens (foreign substances), and initiate the adaptive immune response.
6. What immunological consequences would occur if the thymus was surgically removed from a newborn infant?
If the thymus were removed from a newborn (a neonatal thymectomy), the infant would suffer from severe immunodeficiency. They would be unable to produce a population of mature T-cells, leading to a greatly impaired cell-mediated immunity. This would result in a high susceptibility to infections, particularly from viruses and fungi, and a reduced ability to fight cancerous cells or reject foreign tissue grafts.
7. How is the thymus gland's function related to autoimmune diseases like Myasthenia Gravis?
In many patients with the autoimmune disease Myasthenia Gravis, the thymus gland is abnormal, often exhibiting hyperplasia (overgrowth) or containing a tumour (thymoma). It is believed that a malfunctioning thymus may fail in its role of establishing self-tolerance. It can produce T-cells that incorrectly stimulate the production of antibodies against the body's own proteins, such as the acetylcholine receptors at the neuromuscular junction, leading to the characteristic muscle weakness of the disease.
