Podcast
Questions and Answers
Study Notes
Immune System Composition
- The immune system consists of two main parts: innate immunity and acquired immunity.
Innate Immunity
- Does not depend on previous exposure to antigens
- Not specific
- Creates no memory
- Cannot alter the size of its response to an antigen
Acquired Immunity
- Specific
- Capable of recognizing non-self in a highly specific manner
- Creates a memory of the antigens it encounters
- Developed by exposure to antigens (pathogens)
- Involves lymphocytes and the antibodies they create
- Ability to amplify an immune response when under heavy attack from antigens
- Lymphocytes are created within bone marrow and mature within either bone marrow or thymus
Lymphocytes
- Two main types: T-Lymphocytes (involved in cellular reactions) and B-Lymphocytes (produce antibodies)
B-Lymphocytes
- Stimulated to multiply into blast cells that become either memory cells or antibody-secreting lymphocytes upon contact with a pathogen (antigen)
Antibodies
- Large soluble protein molecules produced by B lymphocytes
- Specifically designed to “fit” onto specific antigens and neutralize them or facilitate their destruction
- Made up of immunoglobulins (glycoproteins found in serum and tissue fluid of mammals)
- Five classes: IgG, IgM, IgA, IgD, and IgE
Immunoglobulin Classes
- IgG: most abundant (70-75% of serum immunoglobulins), contributes to long-term immunity
- IgM: largest antibody, created during primary response (first exposure to a new antigen)
- IgA: found in mucosal linings (intestines), tears, saliva, colostrum, respiratory system, and genitourinary tract
- IgD: function not specified in this context
- IgE: function not specified in this context
Antibody Function
- Latch onto the antigen, forming an antigen-antibody complex that captures the antibody and neutralizes it
- Allow other immune cells to come in and destroy the antigen
- Can signal to other cells to encourage phagocytosis and initiate complement on the antigen
Active Acquired Immunity
- Created by exposure to a pathogen (antigen), either naturally or artificially through vaccination
- Natural active acquired immunity: created by a pathogen infecting an individual, takes time to create antibodies, and signs of disease may be seen
- Artificial active acquired immunity: created by vaccination, involves deliberate exposure to antigen without causing disease
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Description
Learn about the two parts of the immune system: innate and acquired immunity. Understand their differences and how they respond to antigens.