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Thymus Gland

  • This is situated in the anterior part of heart called mediastinal space. It is a bilobed gland. It is originated by third branchial pouch of embryo, i.e. it is endodermal in origin.
  • Thymus gland is well developed in a new born child, but it reduces continuously from adulthood to old age. It remains in the form of a string at last.
  • Its structure is just like a lymph gland. It is covered by connective tissue coat capsule and internally both the lobes are redividing in to small lobules.
  • Each lobule has a dense, darkly staining peripheral cortex and a looser lightly staining central medulla.
  • The cortex consists of densely packed lymphocytes.
  • The medulla consists of reticular epithelial cell, a few lymphocytes and the "Corpuscles of Hassalls" or thymic corpuscles.
  • Thymus gland is related to immune system of body.

Hormones and Functions of Thymus Gland

  • Thymus gland secretes thymosin or thymin hormone, that is proteinaceous in nature/Polypeptide.

Thymus Gland | Biology for Grade 11

  • This hormone helps in immune system of the body.
  • Hassall's corpuscles are found in thymus gland, these are also called thymic corpuscles or epithelial cell or reticular cell, they act as phagocytes.
  • After the birth, T - Cells or T - lymphocytes are matured in thymus gland, then these lymphocytes are releases by thymus gland, reach to lymphatic organs like spleen, payer's patches and lymph nodes & deposited in it.
  • Thymosin hormone stimulates the maturation of lymphocytes to destroy the antigens produced by bacteria or pathogen.
  • According to one of the theories of Ageing  the decline an disappearance of Thymus gland by middle age is the primary cause of ageing.
  • Thymosin helps in the development of sex gland but inhibits sexual maturity in early young age.
  • Thymus provide cell mediated immunity so thymus is also called "Throne of immunity" or "Training school of T-lymphocytes".
  • Thymosin also premote production of antibody to provide humoral immunity. 
  • Secretion of thymin decreases the neuromuscular transmission, so hyper secretion of thymine may cause myasthenia gravis. It provides the antibody against receptor & block the NM junction.

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FAQs on Thymus Gland - Biology for Grade 11

1. What is the thymus gland and where is it located?
Ans. The thymus gland is a small organ located in the upper chest, behind the breastbone and in front of the heart. It is an essential part of the immune system and plays a crucial role in the development and maturation of T-lymphocytes, a type of white blood cell.
2. How does the thymus gland contribute to the immune system?
Ans. The thymus gland is responsible for the production and maturation of T-lymphocytes, which are crucial for the body's immune response. T-lymphocytes help identify and destroy harmful pathogens such as viruses, bacteria, and cancer cells. The thymus gland plays a vital role in training these immune cells to recognize and attack specific targets.
3. What happens to the thymus gland as we age?
Ans. The thymus gland is most active during childhood and adolescence. However, as we age, the thymus gland gradually shrinks and becomes less active. This process, known as thymic involution, leads to a decline in the production and maturation of T-lymphocytes. Consequently, our immune system becomes less efficient in fighting off infections and diseases.
4. Can the thymus gland be affected by diseases?
Ans. Yes, the thymus gland can be affected by various diseases. One common condition is thymoma, a tumor that originates in the thymus gland. Thymomas can be benign or malignant and may require surgical intervention. Additionally, autoimmune diseases such as myasthenia gravis and thymic hyperplasia can also impact the functioning of the thymus gland.
5. Can the removal of the thymus gland affect the immune system?
Ans. The removal of the thymus gland, known as thymectomy, can potentially affect the immune system. However, the impact varies depending on the individual and age at which the thymus is removed. In children, thymectomy may lead to immune deficiencies and increased susceptibility to infections. In adults, the impact is less significant as the thymus gland's role in immune function decreases with age.
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