Exam 3 Review:  Chapter 21:  Nonspecific Resistance

epidermis - The outer, pigmented, protective, innervated but nonvascular layer of keratinized stratified squamous epithelium covering the dermis; the epidermis gives rise to derivatives including hair, nails, sweat and sebaceous glands.  [See Fig. 5.2, p. 154]

mucous membranes - The general term for the specialized epithelial linings which produces a lubricating fluid containing the sticky protein mucin which traps microbes and dirt particles and protects any body structure which is continuous with the external environment except the skin itself.   Examples include the linings of the digestive, respiratory, and urogenital systems and the conjunctival lining of the eyes.

mucus - The viscous, slippery substance which consists chiefly of the glycoprotein mucin, water, sloughed cells and leukocytes, and inorganic salts, and which is secreted, as a moistening and protective lubricant coating capable of trapping many microorganisms, by cells and glands of the mucous membranes of all the cavities which open externally, e.g., the respiratory, digestive, and urogenital tracts.

cilia - The minute hairlike processes, specialized membrane-bound microtubular cell organelles, only clearly observable in the electron microscope, which extend from the surface of a cell or unicellular organism; they are capable of rhythmical motion, and act in unison with other such structures to bring about the movement of the cell or of the surrounding medium; in the human, they are found primarily on the cells lining the respiratory tree and the uterine tubes.  [Note:  cilia are shorter than flagella.]

lacrimal apparatus - Those accessory structuures of the eye which function in the production of tears including the lacrimal glands which synthesize the tears, and the drainage system for the tears, beginning with the openings, lacrimal puncta, to the lacrimal ducts, and the lacrimal sacs and  nasolacrimal ducts; the tears moisten and lubricate the conjunctiva and contain protective compounds to inhibit microbes.

saliva - The watery, slightly alkaline, mixture of secretions from the salivary and oral mucous glands which lubricates the oral cavity, tongue, and teeth, moistens the chewed food, and contains salivary amylase for initial starch digestion, lingual lipase for initial lipid digestion, and various immune defensive chemicals including IgA antibodies and lysozyme.

sebum - The oily semifluid secretion of the sebaceous glands, consisting chiefly of lipids, keratin, and cellular material; with perspiration it moistens and protects the skin.

lysozyme - A hydrolytic enzyme occurring in mucous secretions and in the lysosomes of phagocytic cells, capable of destroying the cell walls (peptidoglycan) of bacteria, particularly gram-positive species.

hyaluronic acid - A gellike proteoglycan (glycoprotein) that is found in connective tissue matrix, the synovial fluid of joints, and the vitreous humor of the eyes and acts as a binding, lubricating, and protective agent; it helps limit the spread of microorganisms in the tissue space.

transferrins - A group of specific transport proteins for ferric iron ions, transport proteins found within the beta globulin group of plasma proteins; cells that require iron have surface receptors to bind these specific iron transport proteins to accomplish the transfer of iron into the cell; because iron ions in the plasma are bound to these specific carriers and not simply dissolved in the water of plasma, they are much less accessible for use by invading microorganisms while also require iron and, therefore, these specific iron transport proteins act as a form of resistance to infection.

interferons - Any of a group of glycoproteins which are produced by different cell types, including leukocytes, in response to various stimuli, such as exposure to a virus, bacterium, parasite, or other antigen, and which prevent viral replication in newly infected cells and, in some cases, modulate specific cellular functions; others inhibit proliferation of normal and malignant cells, impede multiplication of intracellular parasites, augment the actions of Natural Killer (NK) lymphocytes, or play other local regulatory roles in immune defenses; several subtypes and subcategories have been defined, e.g., alpha, beta, and gamma.

complement system - A system of 12 or more plasma proteins, designated C1, C2, etc., which react in an enzyme cascade* to a cell displaying immune complexes or to foreign cell surfaces; these proteins act in various combinations to coat the cell and promote phagocytosis (opsonization), make holes in the cell membrane (cytolysis), attract leukocytes to the area (chemotaxis), and otherwise enhance the inflammatory response.  [Note*:  two pathways to activation of the complement system are recognized, the classical and the alternate pathways.]


 

List:

1. And describe six mechanisms of Innate (nonspecific) resistance to disease and examples of each mechanism.

Mechanisms of Innate (Nonspecific) Resistance to Disease (Examples)
surface barriers epidermis and mucous membranes (coughing, vomiting, diarrhea, and urination help cleanse mucous membranes)
inflammation 3 stage process:  vasodilation and increased vessel permeability, phagocyte migration, and tissue repair
phagocytosis 4 stage process:  chemotaxis, adherence, e.g., opsonization, ingestion, digestion and killing.  major phagocytes are polymorphonuclear neutrophils and monocytes/macrophages.
fever endogenous pyrogens versus exogenous pyrogens
antimicrobial proteins lysozyme, hyaluronic acid, transferrins, interferons, complement system, etc.
Natural Killer ("Null Killer") lymphocytes major defenders against viral infections and tumor cells by means other than phagocytosis

2. The body's surface barriers and the chemicals in their secretions which provide nonspecific resistance to disease. 

Surface Barrier Chemical Secretion(s) Which Provide Nonspecific Resistance To Disease
skin sebum's unsaturated fatty acids, NaCl, H+ ions, lysozyme
all mucous membranes lysozyme, mucin protein for mucus
gastric lining and urinary tract many H+ ions for strongly acidic pH
vaginal lining some H+ ions for mildly acidic pH
dermis and other dense fibrous connective tissue internal barrier, e.g., fascia and joint and organ capsules hyaluronic acid

3. Four specific types of immune cells that function in nonspecific resistance to disease and their function(s).

Cell Function(s)
mast cell = "tissue basophil" releases histamine and other vasoactive regulators to initiate inflammation and phagocyte chemotaxis
polymorphonuclear neutrophils phagocytosis -- first responders
monocytes/macrophages phagocytosis -- slow responders
Natural Killer ("Null Killer") lymphocytes destroy virally-infected cells and tumor cells by means other than phagocytosis

5. Four categories of antimicrobial substances, classes of antimicrobial molecules, that function in nonspecific resistance to disease and the functions they perform.

Category Function(s)
electrolytes and other small molecules salts, hydrogen ions and fatty acids create less favorable surface environments for microbial growth on skin and mucous membranes
enzymes lysozyme (protein catalyst) degrades bacterial cell wall material
interferons proteins which (a) stimulate internal cellular defenses against viral infection and (b) help stimulate and regulate inflammation and other immune defenses
complement proteins plasma proteins which serve as (a) opsonins for phagocyte adherence, (b) chemotactic signal compounds, and (c) lytic agents against cellular antigens.

6. Three types of antimicrobial proteins and their functions.

Protein Type Function(s)
enzymes lysozyme (protein catalyst) degrades bacterial cell wall material
interferons proteins which (a) stimulate internal cellular defenses against viral infection and (b) help stimulate and regulate inflammation and other immune defenses
complement proteins plasma proteins which serve as (a) opsonins for phagocyte adherence, (b) chemotactic signal compounds, and (c) lytic agents against cellular antigens.