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Explore the immune system's first line of defense with a focus on skin barriers, antigens, specific immune responses, T-cells, B-cells, vaccinations, pathogens, and viruses. Learn about the immune system's role in fighting diseases like HIV and how to strengthen immunity.
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First line of defense • The skin serves as a physical barrier to prevent the passage of many disease-causing microorganisms. The skin is also slightly acidic and has good bacteria.
Antigens • Antigens are substances that cause the immune system to attack. An example of an antigen is a surface protein of a flu virus. Cells produce antibodies to fight antigens. Antibodies destroy pathogens directly or signal immune cells that pathogens are present.,
Specific mechanisms of host resistance • This specific immune response enables the body to target particular pathogens and pathogen-infected cells for destruction. It depends on specialized white blood cells called lymphocytes produced in the bone marrow . • T-cells (produced from lymphocytes that matured in the thymus gland) • B-cells (produced from lymphocytes that matured in the bone marrow).
Production and Maturation • All lymphocytes, macrophages and red blood cells produced in bone marrow and T cells mature in Thymus and B cells stay in bone marrow to mature
T-helper • These cells travel through the blood and lymph, looking for antigens –markers on foreign cells. Upon locating an antigen, they notify other cells to assist in combating the invader. • T-helper cells do this through the use of cytokines (or specifically, lymphokines) which help destroy target cells – T-killer cells, activate B cells and stimulate the production of healthy new tissue. Interferon is an example of such a cytokine – one treatment of HIV which infects and kills T-helper cells.
B-cells get turned on by T-helper cells to make specific antibodies that tell macrophage to get them out of the way • T-killer cells get help from T-helper cells to turn on then do the killing
Vaccines • Vaccinations give the body a preview of dangerous antigens. • This allows the body to develop antibodies to fight this antigen. • The body is able to generate an immune response quickly to prevent the disease from doing harm to the body. Brain Pop Video
Common pathogens • Pathogens cause disease. • Bacteria and viral pathogens are the most common causes of human disease.
Bacteria • Bacteria can also cause infections. • When bacteria enters a host they are able to reproduce in large numbers and may produce toxins that affect the health of the host. • The bacteria and their toxins are perceived as antigens by the body. • Antibiotics can be an effective treatment for bacterial infections.
Viruses • Viruses lack ribosomes and are not able to reproduce on their own. Viruses infect cells and use the cellular components to reproduce and spread to other cells.
Viruses • When necessary viruses are treated with anti-viral medications that prevent their reproduction within the host. Antibiotics are not effective against viruses. Examples of viruses • Influenza (flu) • Herpes • HIV
HIV • HIV attacks key cells involved in the bodies immune system. • Infected individuals can not recognize antigens or are not able to mount a response. • These individuals can then be killed by “harmless” diseases.