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Questions and Answers
A pathogen is an organism that causes ______.
disease
The physical barriers of our general defence system include the ______.
skin
Phagocytes are a type of ______ blood cell that can kill microorganisms.
white
Hydrochloric acid, found in the stomach, kills ______.
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The vagina contains bacteria that produce ______ acid to prevent pathogen growth.
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Cilia are small ______ that help move mucus to the pharynx for swallowing.
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Interferons are defence proteins produced by cells infected by a ______.
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Complement Defence Proteins participate in a ______ reaction to foreign microorganisms.
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Cells that have been infected produce a chemical called ______.
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The higher temperature from fever inhibits the ______ from reproducing.
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Monocytes become macrophages, which are large white blood cells that ______ invaders.
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Lymphocytes produce ______ because of antigens.
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The immune system may produce antibodies against ______ substances in the case of allergies.
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In artificial active immunity, a person is inoculated with a non-disease causing part of the ______.
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Natural passive immunity occurs when a child gets antibodies from the ______.
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B-cells work primarily in the lymphatic system, especially in the ______ and lymph nodes.
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Helper T-cells stimulate the reproduction of ______.
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Antibodies act by binding to ______ on the surface of pathogens.
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Memory B-cells remain alive to enhance the ______ B-cell response.
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A tetanus shot is an example of ______ passive immunity.
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The first vaccine was produced by Edward Jenner in ______.
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Antigens trigger the production of specific ______ that fit into their receptor area.
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Study Notes
The Human Immune System
- The body's defense system against pathogens (disease-causing organisms) is comprised of two major components: the general defense system and the specific defense system.
General Defense System
- Non-specific defenses target all pathogens.
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Physical barriers include:
- Skin
- Blood clotting
- Sebaceous and sweat glands (produce bacteria-killing chemicals)
- Lysozyme (found in saliva and tears, kills bacteria)
- Mucous membranes (trap pathogens)
- Nasal hairs (remove microorganisms from the air)
- Cilia (move mucus to the pharynx for swallowing)
- Hydrochloric acid in the stomach (kills microorganisms)
- Vaginal bacteria and low pH (prevent pathogen growth)
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Internal defenses include:
- Phagocytes: White blood cells that engulf and destroy microorganisms, foreign material, and dead cells.
- Macrophages: Large, long-lived phagocytes that act as scavengers throughout the body or remain in fixed locations like the lymph system.
- Complement Defense Proteins: Triggered by the presence of foreign material, causing a series of reactions that burst or engulf pathogens.
- Interferons: Defense proteins produced by virus-infected cells that prevent the spread of the virus.
- Inflammation: A response to infection that causes blood capillaries to dilate and become more porous, leading to swelling, redness, warmth, and pain. Increased white blood cell activity in the area fights the infection. Fever, a systemic inflammation response, inhibits pathogen reproduction.
Specific Defence System
- Specific defenses target specific pathogens.
-
White blood cells are key players:
- Monocytes: White blood cells that develop into macrophages, large cells that engulf invaders. Antigens, parts of the invaders, remain on the macrophage surface, triggering antibody production against future invaders.
- Lymphocytes: Some attack body cells with antigens, others produce antibodies.
- Antibodies: Proteins (immunoglobulins) produced by lymphocytes in response to antigens. Each antibody binds to a specific antigen, preventing the pathogen from entering the host cell, clumping pathogens for phagocytosis, or activating the complement system to burst the pathogen.
- Natural active induced immunity is the protection acquired through the production of specific antibodies after exposure to an antigen.
- Autoimmune diseases occur when the immune system attacks its own cells. Examples include Rheumatoid Arthritis and Multiple Sclerosis.
- Allergies occur when the immune system overreacts to harmless substances, producing antibodies against them. Examples include Hay fever and Asthma.
Artificial Immunity
- Artificial active immunity: Achieved through vaccination with a non-disease-causing form of the pathogen (e.g., dead pathogen, weak pathogen, part of the pathogen, or genetically engineered antigen). This triggers antibody production without causing illness.
- Natural passive immunity: Acquired by a child from the mother, either before birth or through breast milk. This immunity is temporary, lasting only a few months.
- Artificial passive immunity: Occurs when a person is injected with antibodies produced by another organism, providing temporary immunity (e.g., tetanus shot with antibodies from horses).
Lymphocyte Types
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B-cells: Mature in the bone marrow and work primarily in the lymph system. Each B-cell targets a specific antigen, producing only one type of antibody.
- Plasma cells: Rapidly reproducing B-cells, effective but short-lived.
- Memory B-cells: Long-lived B-cells that remember previous encounters with the antigen, allowing for a faster and more effective antibody response upon re-exposure.
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T-cells: Mature in the thymus gland and protect in various ways:
- Helper T-cells: Recognize antigens on the surface of other white blood cells (especially macrophages). They multiply and produce chemicals like interferon, stimulating B-cell production and the reproduction of Killer T-cells.
- Killer T-cells: Destroy abnormal body cells, including virus-infected cells and cancer cells. Stimulated by Helper T-cells, they release perforin, which creates pores in the targeted cells, leading to their destruction (lysis).
- Suppressor T-cells: Inhibit immune responses after the pathogen has been destroyed.
- Memory T-cells: Long-lived cells that remember previous encounters with antigens, stimulating the production of both antibodies and Killer T-cells, contributing to lifelong immunity.
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Description
Explore the major components of the human immune system, including both general and specific defense mechanisms. Understand how the body protects itself against various pathogens through physical barriers and internal defenses such as phagocytes and macrophages.
