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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3:16 minutes

Problem 9

Textbook Question

Collections of lymphoid tissue (MALT) that guard mucosal surfaces include all of the following except:
a. Appendix follicles
b. The tonsils
c. Peyer's patches
d. The thymus

Verified step by step guidance

Understand the concept of MALT (Mucosa-Associated Lymphoid Tissue): MALT refers to collections of lymphoid tissue that protect mucosal surfaces in areas such as the respiratory, digestive, and urogenital tracts. These tissues play a role in immune defense by detecting and responding to pathogens.

Review the listed options: Appendix follicles, the tonsils, Peyer's patches, and the thymus. Determine which of these structures are part of MALT and which are not.

Recall that Appendix follicles, the tonsils, and Peyer's patches are all examples of MALT because they are located in mucosal areas and contribute to immune surveillance in those regions.

Consider the thymus: The thymus is not part of MALT. It is a primary lymphoid organ responsible for T-cell maturation and is located in the mediastinum, not associated with mucosal surfaces.

Conclude that the correct answer is the thymus, as it does not belong to the category of MALT that guards mucosal surfaces.

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Key Concepts

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

Mucosa-associated lymphoid tissue (MALT)

MALT refers to collections of lymphoid tissues found in mucosal surfaces throughout the body, playing a crucial role in the immune response. It includes structures such as the tonsils, Peyer's patches in the intestines, and the appendix. These tissues help protect against pathogens that enter through mucosal surfaces.

Tonsils

The tonsils are lymphoid tissues located at the back of the throat and are part of the body's first line of defense against ingested or inhaled pathogens. They help trap and filter out bacteria and viruses, contributing to the immune response. The palatine, pharyngeal, and lingual tonsils are the three main types.

Thymus

The thymus is a specialized organ located in the chest, primarily responsible for the maturation of T lymphocytes (T cells), which are essential for adaptive immunity. Unlike MALT, the thymus does not guard mucosal surfaces; instead, it plays a critical role in developing the immune system during childhood and adolescence.