Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

20. The Lymphatic System

Overview of Lymphoid Organs

Anatomy & Physiology

20. The Lymphatic System

Overview of Lymphoid Organs

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1:56 minutes

Problem 8

Textbook Question

The lymphoid organ that functions primarily during youth and then begins to atrophy is:
a. Spleen
b. Thymus
c. Palatine tonsils
d. Bone marrow

Verified step by step guidance

Understand the role of lymphoid organs in the immune system. Lymphoid organs are responsible for the production and maturation of immune cells, such as lymphocytes, which help defend the body against pathogens.

Review the function of the thymus. The thymus is a lymphoid organ located in the upper chest, behind the sternum. It plays a critical role in the development and maturation of T lymphocytes (T cells), which are essential for adaptive immunity.

Learn about the thymus's activity during different life stages. The thymus is most active during youth, when it produces and educates T cells. After puberty, the thymus begins to atrophy (shrink) and is gradually replaced by adipose (fat) tissue, although it still retains some immune function.

Compare the thymus to other lymphoid organs listed in the options. The spleen filters blood and helps fight infections, the palatine tonsils trap pathogens entering through the mouth or nose, and bone marrow produces blood cells, including immune cells. None of these organs undergo significant atrophy like the thymus does.

Conclude that the correct answer is the thymus, based on its unique characteristic of being highly active during youth and then undergoing atrophy after puberty.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Thymus

The thymus is a specialized lymphoid organ located in the upper chest, crucial for the development of T-cells, which are essential for the adaptive immune response. It is most active during childhood, where it facilitates the maturation of T-cells from precursor cells. As a person ages, the thymus gradually atrophies and is replaced by adipose tissue, leading to a decrease in T-cell production.

Lymphoid Organs

Lymphoid organs are integral components of the immune system, responsible for the production and maturation of lymphocytes, which are vital for immune responses. These organs include primary lymphoid organs like the thymus and bone marrow, where lymphocytes develop, and secondary lymphoid organs like the spleen and lymph nodes, where immune responses are initiated. Understanding their functions helps in comprehending how the immune system operates throughout different life stages.

Atrophy

Atrophy refers to the gradual reduction in size or function of an organ or tissue, often due to aging, disuse, or disease. In the context of the thymus, atrophy signifies the decline in its size and activity after puberty, which is a normal physiological process. This reduction impacts the immune system's ability to produce new T-cells, highlighting the importance of the thymus during early life.