immune system

fight off invading pathogens

body’s capacity to resist and combat infections.

consists of anatomical, mechanical and physiological barriers as well as cellular and inflammatory mechanisms which are immediately activated in the presence of an antigen

specialized type of immunity which is developed after having an infection or receiving vaccination

• Intact skin (thick layer, sebaceous gland produce sebum that kills bacteria) • Tears (lysozymes/ antibacterial substances) • Saliva • Cilia and mucus in nasopharynx • Mucus and cilia lining the trachea • Ear wax inhibits bacterial growth • Lymphoid tissue • Stomach pH • Natural flora in gu

• Granulocytes (basophils, neutrophils (phagocytes), eosinophils) • Mast cells • Macrophages • Dendritic cells • Natural killer cells • Complements • Inflammation

• B lymphocytes • T lymphocytes • Antibodies • Memory cells

• Immediate (within minutes) • Nonspecific • Lower potency • No memory

• Takes a few days (3-7 days) • Specific • High potency • Memory cells

• Recognition of self vs non-self: Major Histocompatibility complex (MHC) is protein markers on the body cell surface which are recognized by T cells. • Specificity: B and T cells make receptors for only one type of antigen • Diversity: Collectively B and T cells have receptors for over 2 billion antigens. • Memory: B and T cells make memory cells which allows prompt response on re- exposure to infection

plasma cells which are B cells activated by T-helper cells

IgM, IgA, IgD, IgE, IgG

IgM are the first antibodies secreted during immune responses IgG indicate past infections and are efficient in activating complement proteins, neutralizing toxins. IgA are the most abundant antibodies in secretions (tears, saliva, and breast) IgD are part of the B cell receptor and aid the activation of B cell IgE are anchored to the surface of mast cells, eosinophils and basophils which induce degranulation of these cells when bound to antigen

• Neutrophils • Eosinophils • Basophils • Macrophages • Dendritic cells • Natural Killer cells

Neutrophils: are a type of phagocytes that engulf microbes and debris - Eosinophils: these cells target parasites such as worms which are too large to be engulfed - Basophils: the cells contain granules which induce inflammation. - Macrophages: monocytes give rise to macrophages; these cells are large phagocytes. - Dendritic cells: these cells alert the adaptive immune system of the presence of microbes. - Natural Killer cells: cells of the innate immune system that eliminates virus infected cells and usually stimulated by interferons and cytokines

B lymphocytes T lymphocytes Memory cells

• These cells recognize specific antigens • These are antigen presenting cells that activates T cells • Differentiate into plasma cells which produce antibodies which play a primary role in humoral immunity

• These cells recognize specific antigens • There are different types of T cells such as T-helper cells, cytotoxic T cells, T- regulatory cells

• T memory cells: rapidly converted into effector T cells upon re-exposure to the specific invading antigen, thus providing a rapid response to past infection. • B memory cells: these cells remember the pathogen for faster antibody production

An immune response that does not involve antibodies

The state in which the immune system reacts against the body’s own normal components, producing disease or functional changes

An inherited or acquired disorder characterized by the inability to produce an adequate immune response because of an insufficiency or absence of antibodies, immune cells, or both

molecular structure, present on the body of pathogens that are bound by antibodies during an immune reaction.

poisonous substance that when introduced into the tissues are capable of inducing antibody formation