The Immune System Flashcards
Immunity
The body’s specific protective response to invading foreign agent or organism
Immunipathology
the study of diseases that results from dysfunction of the immune system
Components of immune system:
-bone marrow: T cells & B cells
-lymphoid tissue: spleen & lymph nodes
Bone marrow maturation
B lymphocytes = memory cells & plasma cells
thymus
regulator T cells & effector T cells
T lymphocytes mature in:
the thymus, where they also differentiate into cells w/ various functions
B lymphocytes mature in:
the bone marrow
Functions of the Immune System
-to remove foreign antigens such as viruses & bacteria to maintain homeostasis
-phagocytosis: monocytes responsible for engulfing & destroying foreign bodies & toxins
-inflammatory response:
-response to injury or invading organisms
-chemical mediators minimize blood loss, wall off invading organisms, activate phagocytes, promote formation of scar tissue & regeneration of injured tissue
Natural Immunity
-nonspecific response to any foreign invader:
-WBC: release cell mediators such as histmine, bradykinin, and prostaglandins and englulf (phagocytize) foreign substances
-inflammatory response
-physical barriers, such as intact skin, chemical barriers, and acidic gastric secretions or enzymes in tears and saliva
Acquired Immunity
-specific against a foreign antigen
- result of prior exposure to an antigen
-activate or passive
Natural Immunity
-1st line defense
-innate or nonspecific immunity
-blocks the entry of foreign substances
-if antigens do gain entry, the inflammatory response results
Acquired Immunity
-2nd line of defense
-adaptive or specific immunity
-develops over time and in response to antigen exposure
-memory capabilities
Active Immunity
-immunologic defenses developed by person’s own body
-lasts many years; maybe a lifetime
Passive Immunity
- temporary
-results from transfer of a source outside of the body that has developed immunity thru previous disease or immunization
-for ex: transfer of antibodies from mother to infant thru breast feeding; rcving immune globulin thru injections
Humoral Immunity
-B cell mediation
- involved in allergies and anaphylaxis responses
-Protects from:
acute bacterial infections, viruses that enter thru the blood stream or mucosal tissues, bacterial exotoxins
Cell-Mediated Immunity
- T cell mediation
-involved in transplant rejection responses
-Protects from:
chronic bacterial infections, viral respiratory infections, fungal & parasitic infections, some cancer cells
Stages of Immune Response
I. Recognition
II. Proliferation
III. Response
IV. Effector
I. Recognition Stage
-recognition of antigens as foreign
-use of lymph nodes & lymphocytes for surveillance
-lymphocytes recirculate from the blood to lymph nodes and from the lymph nodes back into the bloodstream in a continuous circuit
- macrophages play an important role in helping the circulating lymphocytes process antigens
-both macrophages and neutrophils have receptors for antibodies and complement; as a result, they coat microorganisms w/ antibodies , complement, or both, thereby enhancing phagocytosis
II. Proliferation Stage
- circulating lymphocytes containing the antigenic message return to the nearest lymph node
-stimulate some of the resident T & B lymphocytes to enlarge, divide, and proliferate (increase rapidly in #)
-t lymphocytes differentiate into cytotoxic (or killer) T cells
-B lymphocytes produce and release antibodies
III. Response Stage
- begins w/ the production of antibodies by the B lymphocytes in response to a specific antigen
-cellular response stimulates the resident lymphocytes to become cells that attack microbes; killer T cells
-viral rather than bacterial antigens induce a cellular response
-most immune responses to antigens involve both humoral and cellular responses, although one usually predominates
IV. Effector Stage
Humoral Immunity:
interplay of antibodies
Cellular Immunity:
action by cytotoxic T cells
Null cells
destroy antigen coated w/ antibody
Natural killer cells
defend against microorganisms and some malignant cells
Complement System
amplifies the immune response thru inflammation, chemotaxis, phagocytosis, and cell lysis
3 pathways:
classic, lectin, alternative
