Ch. 32 - Host resistance

• immune system


  composed of widely distributed cells, tissues, and organs; works to recognize foreign substances and microbes
• immunity


  ability of host to resist a particular disease or infection
• nonspecific immune response


  natural immunity; acts as a first line of defense and offers resistance to any foreign material but lacks memory
• specific immune response


  acquired immunity; resistance to a particular foreign material and has memory
• antigens


  recognized as foreign and provoke immune response; presence results in B cell activation and the subsequent production of antibodies
• hematopoesis


  development of white blood cells in the bone marrow; macrophages and dendritic cells mature in the bone marrow while B and T cells come out 'unactivated'
• skin


  strong mechanical barrier of keratin and attached microbes are shed by outer cells; pH is acidic, high salt conc, and subject to periodic drying
• mucous membranes


  form protective covering that traps microbes; bathed in antimicrobial secretions like lysozyme, lactoferrin, and lactoperoxidase
• respiratory system


  mucocilary blanket traps microbes and then are expelled via coughing or sneezing, or wahsed into stomach acid by salivation
• gi system


  gastric acid the stomach, bile and enzymes in the intestines, normal gut microbiota, panteth cells, and shedding of epitheliar cells
• genitals 


  low pH of urine and vagina, lactobacilli in vagina, toxic metabolic end products of urine like urea, and kidney medulla is extremely hypertonic
• cationic peptides


  three classes of which damage bacterial plasma membranes; alpha-helical, defensins, and larger peptides
• alpha-helical peptides


  lack cysteine amino acid residues; e.g. cathlidicin
• defensins


  peptides that are rich in A and C and disulfide linked; found in neutrophils, intestinal paneth cells, and respiratory epithelial cells
• larger peptides


  enriched for specific amino acids and exhibit structural repeats; e.g. histatin in saliva for anti-fungal activity
• bacteriocins


  peptides produced by normal microbiota that are lethal to related species; colicins by e. coli and lantibiotics by gram +
• complement system


  composed of 30+ proteins and complements the antibacterial activity of the body by defending against infection, bridging innate and adaptive immunity, and disposing of wastes
• opsonization


  process in which microbes are coated by opsonins in preparation for recognition/ingestion by phagocytic cells; make up some complement proteins
• classical pathway 


  antigen:antibody complexes result in C1-C4
• MB-lectin pathway


  mannose-binding lectins binds to mannose on pathogen surfaces, results in MBL, MASP 1-2, C4, AND C2
• alternative pathway


  pathogen surfaces, results in C3, factors B and D
• cytokines


  glycoproteins that are released by one cell population that act as signaling molecules for communication (mediation)
• monokines


  released from mononuclear phagocytes
• lymphokines


  released from T lymphocytes
• interleukins


  released from one leukocyte and act on another leukocyte
• CSF's


  stimulate growth and differentiation of immature leukocytes in the bone marrow
• mast cells


  differentiate in blood and connective tissue; contain granules with histamine and play an important role in allergies
• granulocytes


  irregularly shaped with multiple lobes; cytoplasm has granules with reactive substances that kill microbes and enhance inflammation (basophils, eosinophils, and neutrophils)
• basophils


  nonphagocytic and release mediators like histamine and serotonin (important in allergies)
• eosinophils


  defend against parasites and release cationic proteins with reactive oxygen species
• neutrophils


  phagocytic and circulate in blood to migrate to sites of damage; kill ingested microbes with lytic enzymes and reactive oxygen species
• monocytes


  mature into macrophages; phagocytic with a variety of surface receptors
• dendritic cells


  present in small numbers everywhere, phagocytic and display foreign antigens on their surfaces for recognition by other cells
• lymphocytes


  includes T cells, B cells, and natural killer cells; B and T cells only activate after antigen binds to them, then replicate and memory is activated
• natural killer cells


  kill other malignant and infected cells; recognize target cells by either binding to the antibodies coating the infected cell or recognizing cells that have lost their histocompatibility antigen
• skin associated lymphoid tissue


  contains langerhans cell (dendritic that can eat antigens) and intraepidermal lymphocytes (T cells)
• inflammation


  immediate response to injury or cell death; redness, warmth, pain, swelling, and altered function
• acute inflammatory response


  release of mediators from injured cells which initiates the inflammation response; selectons (bind to endothelial cells), integrins (bind to neutrophils), and chemotaxins
• granuloma


  a walled off area formed when phagocytic cells can't destroy a pathogen to protect the body; derives from chronic inflammation