Thymus Gland: Function, Location, Hormones, Structure, Anatomy

What Is The Thymus Gland?

The thymus is a very small, butterfly-shaped organ located in the upper chest, behind the breastbone, and between the lungs. It constitutes an important part of immune system development during childhood. It manufactures and matures the T-cells essential in adaptive immunity. This article will look into the anatomy, functions, role in immunity, disorders, and changes in the thymus at different stages of life.

Anatomy Of The Thymus Gland

One of the more important organs of the lymphatic system, the thymus has the basic function of producing and maturing T-cells. It is at peak operation during childhood, then shrinks in size and progressively degenerates in function throughout life.

Location And Structure

• The thymus is located in the upper anterior part of the chest, just behind the sternum and between the lungs.

• Extends from the lower edge of the thyroid gland to the fourth rib.

Anatomical Structure: Lobes And Lobules

• Extends from the lower edge of the thyroid gland to the fourth rib.

• Has two lobes connected by an isthmus.

• Each lobe is divided into smaller lobules by fibrous septa.

• Lobules contain a cortex rich in immature T-cells on the outer regions, and medulla with mature T-cells on the inner region.

Growth And Development

• The Thymus gland is the largest and most active during early childhood.

• Has an essential role in the development of the body's immune system.

• Involution in Adulthood

• Atrophies after puberty. This process is called thymic involution.

• Functional tissue is gradually replaced by fatty tissue.

Functions Of The Thymus Gland

The major role of the thymus gland is to provide support for the development of the body's immune system, especially facilitating the process of maturation for T cells.

Role In The Immune System

• The thymus is the organ where immature T-cells (thymocytes) mature and differentiate.

• Critical in generating a diverse and self-tolerant T-cell repertoire.

Production Of Thymosins

Secretes thymosins, which are hormones that promote T cell development and function.

Thymic Hormones And Their Actions

• Thymosin alpha 1 activates or enhances T-cell function.

• Thymopoietin: Influences T-cell differentiation.

• Thymulin: Increases the activities of T-cells and natural killer cells.

Thymus Gland And Immunity

The proper immune activity is greatly dependent upon the thymus gland because of the production and regulation of the T-cells.

T-helper Cells

• Activate and enable other immune cells to perform their functions.

Cytotoxic T-Cells

• Lyse virus-infected and malignant cells.

Regulatory T-Cells

• Maintain balance in the immune system and prevent autoimmunity.

Disorders Of The Thymus Gland

The disorders in the thymus gland include serious immune dysfunctions with developmental abnormalities, tumours, and autoimmune diseases.

Hypoplasia And Aplasia

• Hypoplasia: Poorly developed thymus, which results in immunodeficiency.

• Aplasia: The thymus is completely missing; thus, there is a severe degree of immunodeficiency.

Thymomas And Thymic Carcinoma

• Symptoms: Chest pain, cough, difficulty swallowing.

• Diagnosis: Imaging, biopsy

• Treatment: Surgery, radiation, chemotherapy.

Myasthenia Gravis

• An autoimmune disorder where antibodies, in abnormal immune response, attack acetylcholine receptors at the neuromuscular junction.

DiGeorge Syndrome

• A hereditary disorder that causes hypoplasia of the thymus, leading to immunodeficiency.

Thymus Gland At Different Stages Of Life

The changes that the thymus gland undergoes during a lifetime include size, structure, and functional changes.

Thymus Gland In Infancy And Childhood

• Essential for the establishment of a functional immune system.

• High production of T cells to build immune repertoire.

Changes During Puberty And Adulthood

• Thymic involution starts at puberty; thymic tissue is gradually replaced with fat.

• T-cell output significantly decreased; residual function was preserved.

Thymus Gland In Old Age

• Continued involution results in decreased immune responsiveness.

• Increased infections and autoimmune disorders.

Recommended Video On 'Thymus Gland'