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

21. The Immune System

Introduction to the Immune System

Anatomy & Physiology

21. The Immune System

Introduction to the Immune System

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Multiple Choice

What is the immediate action of an allergen when it enters the body for a second time?

It is phagocytized by macrophages.

It activates the complement system directly.

It binds to IgE antibodies on mast cells, causing histamine release.

It triggers the production of IgM antibodies.

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Verified step by step guidance

Understand that an allergen is a substance that can cause an allergic reaction. When it enters the body for the first time, the immune system recognizes it as foreign and produces specific antibodies called IgE.

Recall that IgE antibodies bind to the surface of mast cells and basophils, which are types of immune cells involved in allergic responses.

When the allergen enters the body for a second time, it binds to the IgE antibodies that are already attached to the mast cells.

This binding causes the mast cells to release histamine and other chemicals, leading to the symptoms of an allergic reaction such as inflammation, itching, and swelling.

Recognize that this process is part of the body's immune response and is different from other immune actions such as phagocytosis by macrophages, activation of the complement system, or production of IgM antibodies.