Compare and contrast innate (nonspecific) defenses with adaptive (specific) defenses. Do they attack healthy or infected cells? Do they need priming? What do they both do?
Innate
- attacks anything that does not have your genetic code
- Natural killer cells also take out healthy cells in the process
Adaptive
- T/B lymphocytes fights off particular pathogen, involves antibodies
- T cells fight just infected cells
- must be primed by initial exposure
Both
-Protects against infectious agents and abnormal body cells
What are the 2 lines of defense for the innate defense system? What is the 3rd line of defense? Which one is faster? - chart
First - external body membranes
Second - internal defense
Third - adaptive immune system (T/B cells)
-innate system faster
What are the 5 components of an internal (second line) defense of the innate immune system?
antimicrobial proteins, phagocytes, and NK cells, inflammation, fever
What are some Protective chemicals that inhibit or destroy microorganisms on the skin? (7)
Acidity of skin and secretions – acid mantle – inhibits growth
Enzymes - lysozyme of saliva, respiratory mucus, and lacrimal fluid – kill many microorganisms
Defensins – antimicrobial peptides – inhibit growth
Other chemicals - lipids in sebum, dermcidin in sweat – toxic
What are the mucosa protectors? (2)
Mucus-coated hairs in nose
Cilia of upper respiratory tract
What are the surfaces barriers ward off invading pathogens? (3)
Skin, mucous membranes, and their secretions
- Physical barrier to most microorganisms
- Keratin resistant to weak acids and bases, bacterial enzymes, and toxins
- Mucosae provide similar mechanical barriers
What is opsonization?
phagocytes marks pathogens—coating by complement proteins or antibodies so they can undergo phagocytosis
What are the steps of phagocytosis? What are the 2 types of phagocytes?
neutrophils and macrophages
What is the function of natural killer cells? (3)
- Attack cells that lack “self” cell-surface receptors (MHC)
- Induce apoptosis in cancer cells and virus-infected cells
- Secrete potent chemicals that enhance inflammatory response
What is the purpose of the inflammatory response? (4) When is it triggered?
Prevents spread of damaging agents
Disposes of cell debris and pathogens
Alerts adaptive immune system
Sets the stage for repair
-Triggered whenever body tissues injured
What are the steps of neutrophil mobilization? What follows them?
Neutrophils lead; macrophages follow, then monocytes
Describe the steps of inflammatory response - chart.
Why can inflammation be beneficial?
inflammation causes area to swell with white blood cells that phagocytize pathogens and cleans the area for healing
Describe the mechanism of fever and the role of pyrogens.
- Leukocytes and macrophages secrete pyrogens
- Pyrogens act on body’s thermostat in hypothalamus, raising body temperature
Explain why fever can be beneficial. (High and moderate)
moderate
- Causes liver and spleen to sequester (hold onto) iron and zinc (needed by microorganisms)
- Increases metabolic rate → faster repair
high
-high fever kills microorganisms
What are the 3 main characteristics of adaptive defense?
Specific – recognizes and targets specific antigens
Systemic – not restricted to initial site
Have memory – stronger attacks to “known” antigens
What are the 2 arms of adaptive defense and how are they different?
Humoral (antibody-mediated) immunity
- antibodies circulate freely
- mark target cell for destruction
- extracellular targets
- antibodies produced by B cells (that stay in lymph node) go out
Cellular (cell-mediated) immunity
- directly kill infected cell or
- indirectly release chemicals that enhance inflammatory response/activate other lymphocytes or macrophages
- cellular targets
- T cells directly go to site of infection
What is immunogenecity vs reactivity of complete antigens?
- immuno = ability to stimulate proliferation of lymphocytes
- reactivity = ability to react with activated lymphocytes and antibodies released
What is the difference between complete and incomplete antigens? What are incomplete antigens called? What are some examples?
- incomplete antigens = haptens
- (haptens) not immunogenic by themselves but is if attaches to body proteins
- complete ex - protein, lipids, polysach, nucleic acid
- hapten ex - poison ivy, detergents, cosmetics, animal dancer
What are antigenic determinants? How much do most have?
- certain parts of entire antigen are immunogenic
- Most antigens have several different antigenic determinants.
What are self-antigens? What is an example? What does it do?
- Protein molecules (self-antigens) on surface of cells not antigenic to self but antigenic to others in transfusions or grafts
- MHC unique to individuals
- MHC of APC presents antigens to T lymphocyte to start immune resposne
What are the steps to lymphocyte development, maturation, and activation?
immunocompetance = ability to recognize specific antigen
self tolerance = unresponsive to own antigen
effector cells = fight antigen
Describe the immunological memory (anamnestic) response.
primary immune response - Cell proliferation and differentiation upon first antigen exposure. lag period then peaks
Secondary immune response - Re-exposure to same antigen gives faster, more prolonged, more effective response. responds within hours
What are the 2 types of active humoral immunity?
Naturally acquired—response to bacterial or viral infection
Artificially acquired—response to vaccine of dead or attenuated pathogens
