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Questions and Answers
What is the primary function of the thymus gland?
What is the primary function of the thymus gland?
Where is the thymus gland primarily located?
Where is the thymus gland primarily located?
Which of the following hormones does NOT play a role in the attraction of thymocytes to the thymus gland?
Which of the following hormones does NOT play a role in the attraction of thymocytes to the thymus gland?
What occurs during the negative selection process of T cell maturation?
What occurs during the negative selection process of T cell maturation?
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What is the significance of sphingosine-1-phosphate in T cell maturation?
What is the significance of sphingosine-1-phosphate in T cell maturation?
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Which autoimmune disease is associated with abnormalities of the thymus?
Which autoimmune disease is associated with abnormalities of the thymus?
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At what stage of life is the thymus gland most active?
At what stage of life is the thymus gland most active?
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Which event does NOT occur during the positive selection of T cell maturation?
Which event does NOT occur during the positive selection of T cell maturation?
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Study Notes
Thymus Gland: Definition & Location
- The thymus gland is a primary lymphoid organ in the immune system
- Located in the upper front part of the chest
- Positioned in the anterior superior mediastinum
- Behind the sternum and in front of the heart
Thymus Gland Structure
- Composed of two lobes
- Each lobe has a central medulla and an outer cortex
- Surrounded by a capsule
Thymus Gland Function
- Maturation site for T lymphocytes (T cells)
- Essential for cell-mediated immunity
- T cells originate from hematopoietic precursors in the bone marrow and migrate to the thymus
- Thymocytes are attracted to the thymus by hormones and cytokines
- Examples include thymulin, thymopoietin, and thymosins
- T cell maturation involves two steps:
- Positive selection: T cells that recognize antigens are selected for
- Negative selection: T cells that react to body tissues are eliminated
- Positive selection happens in the cortex, and negative selection occurs in the medulla of the thymus
- Mature T cells leave the thymus, guided by sphingosine-1-phosphate.
- Further maturation occurs in peripheral lymphoid organs
Thymus Gland Development and Size
- Largest and most active during neonatal and pre-adolescent stages
- Size at birth typically 4-6 cm long, 2.5-5 cm wide, and 1 cm thick
- Grows until puberty
- Decreases in size due to involution and replacement with fibrous tissue
- Some T cell development continues throughout adulthood
Thymus Gland Dysfunction
- Congenital problems can lead to immunodeficiency
- Abnormalities can cause decreased T cells and autoimmune diseases such as:
- Autoimmune polyendocrine syndrome type 1
- Myasthenia gravis
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Description
This quiz covers the thymus gland's definition, location, structure, and crucial functions in the immune system. Understand the maturation of T cells and the selection processes that are vital for immunity. Dive into the importance of this primary lymphoid organ in maintaining a healthy immune response.
