chapter 43 the body’s defense. i. nonspecific mechanisms a.skin & mucous membranes * physical...
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I. Nonspecific mechanisms
A. Skin & Mucous Membranes
* physical & chemical (skin 3-5 pH)
* saliva, tears & mucus; perspiration
* nostril hairs
B. Phagocytic White Cells & Natural Killer Cells
* neutrophils: cells that become phagocytic in infected tissue
* monocytes: become macrophages (phagocytize microbes)
* easinophils: against larger invaders (like worms)
C. Antimicrobial Proteins
* complement system: cause lysis of microbes
* interferons: inhibit viral reproduction; good against short term; made with recombinant DNA
D. The Inflammatory Response
* caused when damage to tissue
* vasodilation = increase blood flow & redness (caused diffusion of fluid = edema)
* chemical signals initiate = histamine (vasodilation) & prostaglandins (increase blood flow)
* migration of phagocytic cells
* more widespread response can occur in severe case (appendicitis)
* fever due to toxins or leukocytes
II. Defense of specific invadersA. Key Features of Immune System
Specificity* antigen = foreign substance that
elicits immune response* antibody = antigen-binding
proteinsDiversity: responds to different invadersMemory: recognizes previously encountered antigens (acquired immunity)Self/Non-Self Recognition
B. Active vs. Passive Acquired Immunity
* active = recovery from disease (artificial w/ vaccine)
* passive = transferred from one individual to another (pregnant) ; temporary
C. Humoral Immunity & Cell-Mediated
* humoral = produce antibodies in response to toxins, free bacteria in body fluids
* cell-mediated = intracellular; bacteria, cancer, transplants (depends on direct action of lymphocytes)
D. Cell of Immune System
* 2 main classes of lymphocytes:
1. B cells: humoral (antibodies)
2. T cells: cell-mediated
* kept in lymph organs
III. The immune system’s capacity to distinguish self from nonself is
critical in blood transfusion & transplants
A. Blood Groups* ABO blood groups = nonself recognition (antigen present on surface of RBC’s = not antigenic to that person but may be foreign to another)
A has A antigen & make anti-B antibodies
• Blood group antibodies --- agglutinate
AB = universal recipient
O = universal donor
(not bad for fetus --- these antibodies can’t cross)
• Rh factor- problem when mother is negative & baby is positive* mother makes antibodies when blood crosses usually only a problem in 2nd child* Rh antibodies can cross placenta & destroy RBC’s of fetus* receive anti-Rh antibodies which destroy positive red cells before mother develops memory
B. Tissue Grafts & Organ Transplants
* MHC (proteins embedded in plasma membranes of cells) = biochemical fingerprint unique to each individual
- complicates tissue grafts & organ transplants
IV. Abnormal immune function leads to disease states
A. Autoimmune disease: immune system reacts against self* some cases = immune reactions against components of own cells = lupus* rheumatoid arthritis = inflammation damages cartilage & bones in joints* destruction of insulin-producing pancreas cells = insulin-dependent diabetes
B. Allergy: hypersensitivity of body’s defense to environmental antigens (allergen)
* IgE antibodies recognize pollens as allergens
* antihistamines used to treat (histamines cause dilation & increased permeability of small blood vessels)
• Anaphylactic shock = life-threatening reaction to injected antigens (sudden dilation = decrease blood pressure; death in a few minutes); epinephrine may be injected
C. Immunodeficiency:* individual is inherently deficient in either humoral or cell-mediated immune defenses* not all inborn: Hodgkins disease (cancer damages lymphatic) or physical & emotional stress (adrenal hormones)* direct links between nervous & immune system