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The immune system

The immune system. The Body’s Defense. The Immune System. Immunity is the ability of the body to defend itself against infectious agents, foreign cells, and even abnormal body cells, such as cancer cells.

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The immune system

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  1. The immune system The Body’s Defense

  2. The Immune System • Immunity is the ability of the body to defend itself against infectious agents, foreign cells, and even abnormal body cells, such as cancer cells. • The immune system is another example where distinct three-dimensional proteins have specific functions. • Cell communication and recognition play a vital role in the immune system. • Other examples of this communication in body cells are: • Enzymes – catalysts in chemical reactions • Hormones – insulin, oxytocin • Hemoglobin – transport proteins in the blood • Actin/Mysin – muscle contraction

  3. THE IMMUNE SYSTEM • Some important proteins used in the immune system are: • Antibodies • Fibrin • Antigen • Immunoglobulins • TYPES OF IMMUNITY • Nonspecific immunity • Specific immunity

  4. NONSPECIFIC IMMUNITY Definition: Defenses that are effective against any foreign agent that enters the body • Physical Barriers • Intact skin is a physical barrier • Mucus membranes that line body passages, and cilia that line the respiratory tract, trap debris • Chemical Barriers • Tears • Sweat • Saliva • Oil

  5. NONSPECIFIC IMMUNITY • Phagocytosis • Means “cell eating” • Leukocytes engulf and digest bacteria or other invaders • Leukocytes found in blood and tissues • Natural Killer Cells • Type of leukocyte that recognizes body cells with abnormal membranes • Cell membranes can be altered by viruses • Destroys abnormal cells on contact by secreting a protein that destroys the cell membrane

  6. NONSPECIFIC IMMUNITY • Fever • Sign that the body is defending itself • Should not always be eliminated, but monitored • Interferon • Group of substances that stimulate the immune system • Produced by virus infected cells

  7. NONSPECIFIC IMMUNITY • Inflammation • Causes: • Trauma or injury • Physical irritant (a piece of glass, a wasp sting) • Pathogenic organism (bacteria, viruses, fungi or parasites) • Signs and Symptoms • Redness • Swelling • Heat • Pain

  8. NONSPECIFIC IMMUNITY • Inflammatory Response from “Human Diseases – A Human Approach”

  9. Check for Understanding • What is an example of a physical barrier? • Saliva • Intact Skin • Hair • What is an example of a chemical barrier? • Antibacterial soap • Interferon • Tears

  10. Check for Understanding • What occurs during phagocytosis? • Bacteria is engulfed and digested • A chemical is released that destroys bacteria • Histamine is released • How do natural killer cells recognize invaders? • By their shape • By their abnormal membrane • By the chemical they release

  11. Check for Understanding • What chemical is released by injured cells? • Histamine • Interferon • Exudate Great work! Now let’s continue…

  12. SPECIFIC IMMUNITY Definition: Defenses that are effective against particular identified foreign agents • Specific immunity operates in the body via the lymphatic system. This system includes: • Lymphatic vessels • Lymph nodes • Lymph organs Within lymph nodes, macrophages engulf and digest bacteria, viruses, and other foreign materials

  13. SPECIFIC IMMUNITY • ANTIGEN • A foreign element that triggers the immune response • They are unique and differ from each other in structure

  14. SPECIFIC IMMUNITY • QUESTION: SINCE ANTIGENS ARE UNIQUE, HOW DOES THE IMMUNE SYSTEM DEFEND AGAINST THEM? • ANSWER: BY USING THE FOLLOWING • HUMORAL IMMUNITY • CELL-MEDIATED IMMUNITY They work together to fight off foreign invaders!

  15. SPECIFIC IMMUNITY • HUMORAL IMMUNITY • Antibodies • CELL-MEDIATED IMMUNITY • T lymphocytes • Produced by the thymus gland • Several types with different functions (ie: Cytotoxic, Helper, and suppressor) • B lymphocytes • Plasma cells • Immunoglobulins (5 types: IgG, IgM, IgA, IgE, IgD) • Memory cells

  16. VACCINATION • Two types of artificial immunity can be administered: • Active Immunity – person receives vaccine as the antigen and he or she forms antibodies to counteract it • Immunizations (suspension of weakened organisms) • Treated to deactivate the organism • Passive Immunity – person is given doses of preformed antibodies from immune serum of an animal, usually a horse • Short lived • Acts immediately • Also obtained in breast milk

  17. HYPERSENSITIVIES - ALLERGIES • Definition: when the immune response causes tissue damage and disordered function rather than immunity • May manifest: • Locally – occur in confined areas such as skin and/or mucus membranes • Systemically – anaphylaxis (bees and peanuts are common) • There is an overproduction of IgE (type of immunoglobulin) which ultimately results in the release of histamine • Tissue and organ transplants are an example of Type IV or delayed hypersensitivity reaction

  18. AUTOIMMUNITY We now understand that our bodies are equipped to defend itself from foreign invaders, but autoimmunity is when the immune system does not distinguish between “self” and an invader • Definition: when an individual develops antibodies to their own tissues or self-antigens. • The immune response normally recognizes the difference between the individual’s own tissues and those of invaders. This is known as tolerance. When tolerance fails, an autoimmune disease may be the result • Examples of autoimmune diseases are: lupus, scleroderma, and Sjogren’s Syndrome

  19. IMMUNE DEFICIENCY • AIDS (immunodeficiency syndrome) • Destroys the immune system • Causative agent is the human immunodeficiency virus (HIV) • Attacks helper T lymphocytes killing them • Helper T cells normally activate B-cell lymphocytes so this does not happen • Immune response is crippled and body becomes susceptible to infections and tumors that a healthy immune system could easily control

  20. Check for Understanding • Specific immunity operates in the body via the: • Cardiovascular system • Lymphatic system • Respiratory system • Where are T lymphocytes produced in the body? • Thymus • Thyroid • Liver

  21. Check for Understanding • Which of the following is an example of a autoimmune disease? • Cancer • Anaphylaxis • Lupus • An example of Passive Immunity is: • Breast milk • Immunizations • Allergy shots

  22. Check for Understanding • An example of a hypersensitivity is: • Anaphylaxis • Organ transplant rejection • Both are example of hypersensitivity • This virus destroys helper T cells: • AIDS • Influenza • HIV

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