The bodys defenders

ContentsPathogens and diseaseMajor types of defenseNonspecific or innate immunityExternal defensesInternal defensesSpecific or acquired immunityLymphocyte activityTypes of acquired immunityHumoral (antibody-mediated) responseCell-mediated responseImmunity to secondary infectionActive immunityPassive immunityBlood groups and transfusionsImmune disorders

Pathogens and diseaseBacteria

Two major types of defenses

Innate (nonspecific) immunity First line: External defensesExternal defenses

Innate immunity Second line: Internal defensesPhagocytes Attach to and ingest invading microorganismsInitiates the inflammatory responseMacrophages migrants or in lymph organsAntimicrobial proteinsComplement system lysis of invading cells, triggers inflammationInterferons activate macrophages, prevent cell-to-cell spread

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Inflammatory responseInnate immunity Second line: Internal defenses (cont.)http://www.sumanasinc.com/webcontent/anisamples/dynamicillustrations/inflammatory.htmlChemicals involved Histamines Prostaglandins Chemokines Pyrogens

Innate immunity Second line: Internal defenses (cont.)Natural killer (NK) cellsPatrol bodyAttack virus-infected body cells and cancer cellsApoptosis (cell death) in cells attackedCoelomocytes in invertebrates function in nonspecific immunity

Specific (acquired) immunityThird line of defenseLymphocytesFound in blood and lymphTypesB cells mature in marrowT cells mature in thymusHelperCytotoxicDisplay specificity to antigens (antibody generator)Have membrane-bound antigen-receptors

Two types of specific immune responses

B and T cells generate clones ofshort-lived activated effector cellslong-lived memory cells

Antibody action

Immunity memory cells initiate a faster, more efficient response upon reinfection

Active immunityOwn system develops antibodiesDevelops naturally in response to infectionDevelops following immunizationLong-lasting protection but may take a long time

Passive immunityAntibodies are passed from mother to fetus via the placentaAntibodies are passed from mother to infant via breast milk (colostrum)Antibodies may be injected into a nonimmune personImmediate, short-term protection

Blood groups and transfusionsProblems with transfusions and transplantsAntigens on RBCs will determine a persons blood type: A, B, AB, O bloodAnother RBC antigen: Rh factor Rh+ or Rh-

Immune disorders/diseasesAllergies hypersensitive responses to antigens called allergensAutoimmune diseases immune system loses tolerance for self and turns against certain molecules of the bodyImmunodeficient diseasesInborn or primaryAcquired or secondaryAIDS HIV attacks helper T cells