immunology Flashcards
clinical infection
infections with signs and symptoms
sub-clinical infection
infection with pathogen but no symptoms
latrogenic infection
from a medical practitioner/ intervention (hospital)
How are respiratory infections transmitted?
droplets (cough-sneeze), saliva, soil dust, water aerosols
sneezing propels mucus droplets from the respiratory mucosa, transmitting flu or cold virus to a new host
Zoonoses is a term used for what kind of disease?
direct animal-to-human, animal-vector-human, human-vector-human
endemic
Disease present in a community (region) all the time, usually only clinical in a few
epidemic
Wide spread disease within a community (region), affecting many people but only occasionally present
pandemic
Wide spread epidemic, not confined to a single community or region (more than one continent)
Sporadic
Widely scattered disease, occurring singly, irregularly, infrequently
What is “Epidemiology”?
The study of the spread, frequency, distribution of disease
Explain the difference between Morbidity and Mortality
Morbidity
- Number made ill by infective agent
Mortality
- Number of deaths caused by infective agent
- Explain the difference between Incidence and Prevalence
Incidence
- Number of new cases over specific period
Prevalence
- Number of cases (infected or diseased) at a given time (old and new cases)
In epidemiological terms how would you classify the disease “AIDS”.
pandemic
What factors influence the spread of disease in a community?
- Virulence of the pathogen
- Pathogen transmission mode
- Population susceptibility – Immunity
List four ways of preventing the spread of disease in a community.
- Prevent contamination of water supplies
- Immunization
- Educate the public
- isolate diseased persons
Which disease of the following disease type would most likely spread quickly through the Perth community and why? A) Gastroenteritis, B) A sexually transmitted disease, C) a Respiratory disease
C) a respiratory disease as Perth’s population tend to have higher hygiene standards and good public education, making gastroenteritis and STI less likely to spread quickly. A respiratory disease may be spread via droplets, and so when people cough or sneeze without covering, infectious pathogens can be transmitted.
List the stages of infectious disease
incubation prodromal invasive decline convalescence
What are the two branches of the immune system?
innate and adaptive
How does skin protect against bacteria?
innate: first line of defence; mechanical barrier
it is difficult for microbes to penetrate the skins dry, dead out cells. In addition, the sebaceous glands produce oils which also help to kill microbes
contains normal flora to provide competition for pathogenic microbes that want to grow on the skil
what types of WBCs are phagocytic
Neutrophils, monocytes, eosinophils
What type of white blood cell (WBC) is mainly involved in the adaptive immune system?
Lymphocyte- T and B cells
What antibody types are involved in the primary and secondary immune response?
Primary response - Immunoglobulin M (IgM)
Secondary response - Immunoglobulin G (IgG)
What type of lymphocyte is involved in cell mediated immunity?
Cytotoxic T Cells and natural killer cells
List the ways antibodies fight infection.
Activate complement
trigger phagocytosis
neutralise viruses and toxins
agglutination
- List the antibody isotypes .
IgG
- Monomer, most abundant in serum – largest amount, long term immunity, can cross placenta
IgA
- Monomer in serum, dimer in saliva and secretions, most abundant total – saliva and mucosal surfaces, tear, nasal fluids, milk
IgM
- Pentamer, primary response – first Ab to appear during an infection
IgE
- Monomer, stem binds mast cells, basophils and eosinophils causing release if granules – anti-parasite, allergy
IgD
- Monomer, attached to B cells, antigen receptor for activation – largest Ab - Ag receptor on B cells
What are the 4 cardinal signs of inflammation and how do they come about?
redness (increased blood flow)
heat (increased blood flow)
swelling (lymphatic fluid)
pain (inflammatory substances released cause pain)
Describe the difference between humoral and cell mediated immune responses.
humoral immunity - antibody mediated, action against extracellular invaders, produced by B lymphocyte, uses antibodies as main form of immune response
cell mediated immunity - lymphocyte directly/ indirectly kill infected cells, act against intracellular invaders, cytotoxic T cells (Tc), uses cytotoxic T cells and natural killer cells as main form of immune response
List and describe the types of T cells
cytotoxic T cell - destroys host cells that harbor anything foreign, directly responsible for cell mediated immunity
T helper Th - modulate activities of other immune cell - stimulate
T regulator Treg - turn off an immune response - inhibit
What is the MHC and what is its purpose?
MHC refers to the Major Histocompatabilty Complex. The function of MHC is to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells. The consequences are almost always deleterious to the pathogen; viruses infected cells are killed, macrophages are activated to kill bacteria living in their intracellular vesicles, and B-cells are activated to produce antibodies that eliminate or neutralise extracellular pathogens
Describe the difference between passive and active immunity.
- Passive immunity relies on the administration of
antibodies (already directed against an antigen),
whereas active immunity involves the administration
of the antigen. - Passive immunisations are generally administered
post infection/toxin, wheres active immunisations are
prophylaxis, to prevent future infection. - In passive immunity, the recipient does not produce
an immune response of their own, unlike in active
immunity where they produce their own antibodies
and memory cells. - Passive immunity is short lived, whereas active
immunity is long term.
How do autoimmune diseases occur?
Autoimmune diseases occur when, instead of attacking foreign bacteria, viruses, or other sources of infection, the immune system attacks healthy organs and tissues. It’s not known why this happens, although conditions most often affect people with a genetic predisposition. Type 1 diabetes is an example.
