Final Exam Study Guide Flashcards
What are the different types of transmission for contact diseases?
- direct: skin-to-skin, mucous membranes, bodily fluids
- indirect: contaminated surfaces, instruments, clothing
What are the different ways contact diseases spread in healthcare and daily life?
- frequent skin contact
- use of shared medical equipment
- high-contact areas (gyms, bus, schools)
Who are the most at risk for contact diseases?
immunocompromised individuals
What are STIs?
previously known as STDs
- sexually transmitted infections
What are the different ways of spreading STIs in sexual and everyday settings?
sexual contact
- direct transmission
- exchange of bodily fluids
- skin-to-skin contact
everyday settings
- shared personal items
- non-sexual blood contact
What are the different ways to test for STIs?
at home test kits
- OraQuick
- uritest dipstick test
What are the pros and cons of at-home STIs home testing kits?
pros
- more cases are diagnosed
- better access with patients
- quicker treatment
cons
- cost
- privacy concerns
- concerns about accuracy
What are the different stages of syphilis?
- primary stage: chancre at the site of infection about 3 weeks after exposure
- secondary stage: skin and mucosal rashes, especially on the palms and soles
- latent stage: no symptoms
- tertiary stage: years after latency
What is the difference between vaginitis and vaginosis?
vaginitis: inflammation of vagina
vaginosis: no in inflammation
What environment does Trichomoniasis grow in?
vagina and urethra
- when normal acidity of the vagina is disturbed
What does HIV stand for?
human immunodeficiency virus
What does HIV attack?
immune system, specifically CD4+ cells
What is CD4+?
t-helper cells
What is the role of the T helper cell?
produces cytokines and differentiates into Th1, Th2, Th17, and memory cells
What are the different T helper cells and what is their relation to HIV?
- TH1 cells: HIV leads to depletion of CD4+ TH1 cells (weakens immune system’s ability to combat intracellular pathogens)
- TH2 cells: balance between TH1 and TH2 is ruined in HIV (TH2 more dominant = reduced cell-mediated immunity)
- TH17 cells: HIV infection impairs TH17 cells, contributing to the weakening of mucosal defenses and gut barrier integrity (leads to systemic inflammation and microbial translocation
- Memory cells: HIV establishes reservoirs in memory CD4+ T cells = hard to eradicate virus entirely
What type of virus is HIV?
retrovirus
What is the structure of HIV?
- 2 identical + stranded RNA genome molecules
- reverse transcriptase enzyme
- phospholipid envelope
- gp 120 glycoprotein spikes
capsid
How does the HIV attach and enter susceptible CD4+ host cells?
1) Attachment: gp120 spike attaches to a receptor and CCR5/CXCR4 receptor (gp41 helps with fusion of HIV with the cell)
2) virus envelope merges with the cell membrane
3) entry pore is created, so viral envelope remains behind and HIV uncoats, releasing RNA core for directing synthesis of new viruses
What is the mechanism of RNA and DNA for using reverse transcriptase in the pathogenicity of HIV?
1) viral RNA is transcribed into DNA using reverse transcriptase
2) DNA is integrated into the host’s chromosomal DNA
3) Virus undergoes rapid antigenic changes and a high rate of mutation
What is the difference between active and latent infections?
active: new viruses bud from the host cell
latent: DNA is hidden in the chromosome as a provirus (some become memory cells that serve as reservoir for HIV)
What are the different subtypes of HIV?
HIV1: related to viruses that infect chimpanzees and gorillas
HIV2: longer asymptomatic period with lower viral load and mortality rate than HIV-1
How is HIV transmitted?
- sexual contact
- breast milk
- transplacental infection of a fetus
- blood-contaminated needles
- organ transplants
- artificial insemination
- blood transfusion
What are the different phases of infection for HIV?
Phase 1: asymptomatic or lymphadenopathy
Phase 2: CD4+ T cells decline steadily
Phase 3: AIDS develops, CD4+ is count below 200 cells/microliter
Who is more impacted in response in HIV exposure?
older adults and young children
- those without fully developed immune system
Who are considered long-term survivors?
- low viral load
- effective CTLs
What are the different stages of HIV infections?
- acute: flu-like symptoms (high viral load)
- chronic: asymptomatic or mild symptoms, virus continues to replicate
- AIDS: severe immune system damage; opportunistic infections occur
What are the different ways to diagnose HIV?
- seroconversion
- ELISA
- western blot
- APTIMA (RNA testing)
- PCR
- nucleic acid hybridization
Why is it challenging to make a vaccine for HIV?
- no model or natural immunity to copy
- lack of research animal
- lack of understanding retrovirus mechanism
- high mutation rate
What does AIDS stand for?
Acquired immunodeficiency syndrome
Where are the most cases of AIDS worldwide?
Africa
What part of the world are AIDS cases stem from injected drugs?
Eastern Europe and Cental/Southeast Asia
How does HIV progress to AIDS?
1) HIV infects CD4+ T cells
2) HIV multiplies fast and destroys CD4+ cells
3) Immune system becomes less able to fight infections
4) CD4+ T cells < 200 cells/microliter = AIDS
What are the different ways you can prevent AIDS?
- condoms
- HIV testing
- sex education
- safe infant feeding programs
What are the different ways you can treat AIDS?
- HAART: highly active antiretroviral therapy
- fusion/cell entry inhibitors
- reverse transcriptase inhibitors (NRTIs and NNRTIs)
- integrase inhibitors
- protease inhibitors
- maturation inhibitors
How does immunological diseases come to be?
immune system malfunctions
- overreacting
- underreacting
- attacking the body’s own tissues
What are the different categories of immunological disorders?
- hypersensitivities
- autoimmune diseases
- immunodeficiencies
What is hypersensitivity?
exaggerated immune responses to harmless substances
What are the different types of hypersensitivity?
- anaphylactic
- cytotoxic
- immune complex
- delayed cell-mediated
How long does type I take to be sensitized and how?
immediately
- after a person who is sensitized to an antigen is re-exposed to that antigen
Which antibodies are associated with type I?
antigens combine with IgE antibodies
- IgE attaches to mast cells and basophils and undergoes degranulation
What are the different mediators that are released during type I?
- histamine
- leukotrienes
- prostaglandins
What is the difference between systemic and localized anaphylaxis?
systemic: anaphylactic shock (needs epinephrine treatment)
localized: ingested or inhaled antigens (symptoms and treatment depend on route of entry)
How can you prevent type I hypersensitivity?
desensitization therapy - increasing dosages of antigen injected beneath the skin
What are the different antibodies associated with type II?
IgG or IgM antibodies + antigenic cell
How is the ABO blood group associate with type II?
Antibodies form against certain carbohydrate antigens on RBCs
What are the different blood types and their antibodies?
A - anti-b antibodies
B - anti-a antibodies
AB - neither anti-a nor anti-b antibodies
O - anti-a and anti-b antibodies
How does the Rh blood group system associate with type II?
Rh+ blood given to Rh- recipient will stimulate anti-Rh antibodies in the recipient
Explain the Rh blood group example of the pregnant mother and how she is treated.
Rh- mother with Rh+ fetus causes the mother to produce anti-Rh antibodies
- second Rh+ fetus will receive anti-Rh antibodies = damaged fetal RBCs
What is the different drug-induced type II reactions?
- thrombocytopenic purpura
- agranulocytosis
- hemolytic anemia
What is the mechanism of type III reaction?
1) immune complexes are deposited in wall of blood vessel
2) presence of immune complexes activates complement and attracts inflammatory cells (neutrophils)
3) enzymes released from neutrophils cause damage to endothelial cells of basement membrane
What is Arthus reaction?
side-effect of toxoid-containing vaccines
What is the type IV immune response?
delayed-cell mediated
- delayed hypersensitivity
What is the allergic contact dermatitis?
haptens combine with proteins in the skin, producing an immune response
What is autoimmune disease?
immune system responds to self-antigens, causing damage to the organs
What types of hypersensitivities associated with autoimmune disease?
- cytotoxic
- immune complex
- cell-mediated
What is the mechanism of multiple sclerosis?
autoantibodies, t cells and macrophages attack myelin sheath of nerves
What does multiple sclerosis compromise?
nerve impulse transduction
What type of hypersensitivity is multiple sclerosis?
Type 2 cytotoxic autoimmune reactions
What are the different diseases associated with type III hypersensitivity autoimmune reactions?
- graves’ disease
- myasthenia gravis
- systemic lupus erythematosus
- rheumatoid arthritis
What type III disease causes hyperthyroidism?
graves’ disease
What type III disease causes muscles to fail to receive nerve signals?
myasthenia gravis
What type III disease causes butterfly rashes?
systemic lupus erythematosus
What type III disease causes immune complexes form in the joints?
rheumatoid arthritis
What are the different diseases associated with type IV autoimmune reactions?
- insulin-dependent diabetes mellitus
- psoriasis
- psoriatic arthritis
What are the possible causes of the different autoimmune diseases?
- cross-reaction with antibodies against streptococcal antigen
- immune complexes involving antibodies against DNA
- T cells destroy insulin-secreting cells
- destruction of myelin sheath of nerve cells
- antibodies against acetylcholine receptors
- antibacterial antibodies react with intestinal mucosa
What is HLA and how is it related to the reactions of transplantations?
Human Leukocyte Antigen
- donor and recipient must be matched by tissue typing
- uses standardized antisera or monoclonal antibodies specific for HLAs
What cells can attack transplants?
T cells, macrophages, complement-fixing antibodies
What are stem cells?
master cells capable of renewing themselves and differentiating into organ-specific specialized cells
What are the different types of stem cells?
- embryonic stem cells
- adult stem cells
- bone marrow (hematopoietic stem cells)
What are the different types of grafts in regard in transplants?
- autograft
- isograft
- allografts
- xenotransplantation product
What are xenotransplantation products?
use of nonhuman tissue
What are the different immunodeficiencies and their examples?
1) Congenital immunodeficiencies
- selective IgA deficiency
2) Acquired immunodeficiencies
- due to drugs (corticosteroids)
- due to cancers (leukemias, lymphomas)
- due to infection (HIV/AIDS)
What is a vaccine?
suspension of organisms that induce immunity
How did vaccinations come to be?
Edward Jenner inoculated cowpox to prevent smallpox
- vacca = cow
What is the purpose of a vaccine?
primary immune response: leads to formation of antibodies and memory cells
What is herd immunity?
immunity in most of the population
What are the different vaccines associated with the diseases we went over in class?
- polysaccharides (purified)
- DTaP, Tdap, Td
- attenuated virus
- inactivated virus
- antigenic fragments of virus
- killed virus
- live vaccinia virus
What is the difference between live attenuated and inactivated killed vaccine?
live: weakened pathogen & closely mimic actual infection & confers humoral immunity
inactivated: induce mostly humoral immunity
What are the different types of vaccines?
- subunit vaccines
- recombinant vaccines
- toxoids
- virus-like particle vaccines
- polysaccharide vaccines
- conjugated vaccines
- nucleic acid vaccines
- recombinant vector vaccines
What are adjuvants?
chemical additives added to vaccines to improve effectiveness
What is the difference between sensitivity and specificity?
sensitivity: chance that the test is reactive if the specimen is a true positive
specificity: chance that a positive test will not be reactive if the specimen is a true negative
What are the different immunological-based diagnostic test?
- interactions of humoral antibodies with antigens
- known antibody can identify an unknown pathogen
- known pathogen can identify an unknown antibody
What are the two different tests for precipitation reactions?
immunodiffusion tests
immunoelectrophoresis
What are the different agglutination reaction test?
- direct agglutination tests
- seroconversion
- indirect/passive agglutination tests
- hemagglutination
What are neutralization reactions?
antigen-antibody reaction where the harmful effects of an exotoxin or a virus are blocked by antibodies to the toxin
What are complement-fixation reactions?
complement serum protein binds to and is fixed to the antigen-antibody complex
What are the different fluorescent-antibody tests?
- direct fluorescent-antibody tests
- indirect fluorescent-antibody tests
- fluorescence-activated cell sorter
What is ELISA?
enzyme-linked immunosorbent assay
- direct: detects antigens
- indirect: detects antibodies
What is western blotting?
identifies proteins by electrophoresis and a blot
What is the difference between sepsis and asepsis?
sepsis: bacterial contamination
asepsis: absence of significant contamination
What are the different ways to kill microorganisms?
- sterilization
- commercial sterilization
- disinfection
- antisepsis
What is the difference between degerming and sanitization?
degerming: mechanical removal of microbes from a limited area
sanitization: lowering microbial counts on eating utensils to safe levels
What is the rate of the microbial death dependent upon?
- number of microbes
- environment
- time of exposure
- microbial characteristics
How does heat affect the growth of organisms?
denatures enzymes
What is the difference between TDP, TDT, and DRT?
TDP (thermal death point): lowest temperature where all cells in a liquid culture are killed in 10 minutes
TDT (thermal death time): minimal time for all bacteria in a liquid to be killed at a particular temperature
DRT (decimal reduction time): minutes to kill 90% of a specific population of bacteria at a given temperature
How does moist heat sterilization affect the growth of organisms?
coagulates/denatures proteins
What is an autoclave?
steam under pressure
How does dry heat affect the growth of organisms?
kills by oxidation
How does filtration help sterilize from microbial growth?
can filter out viruses and large proteins
What are the different radiation methods affecting the growth of organisms?
- ionizing radiation
- nonionizing radiation
- microwaves
How do essential oils work to affect microbial growth?
disrupts cell membranes of microorganisms
What are examples of halogen solutions used for disinfectants?
iodine
chlorine
What are the different metals to prevent microbial growth?
silver nitrate
mercuric chloride
copper sulfate
zinc chloride
What are the different chemical food preservatives?
sulfur dioxide
organic acids
nitrites/nitrates
What are peroxygens used for?
contaminated surfaces and food packaging
