immunity & infection Flashcards
1
Q
infection & toxins
A
- infection = invasion of the body by microorganisms
- toxins = poisonous substances
- systemic infection invasion by microorganism that spreads through blood or lymphatic system to large portions of body
2
Q
chain of infection - pathogen
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- a microorganism that causes disease
3
Q
chain of infection - reservoir
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- person, animal, or environmental component (ex; soil or water) where pathogen lives
4
Q
chain of infection - portal of exit
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- to transmit infection, pathogen must leave reservoir (ex; saliva, mucous membranes, blood, faces, nose & throat discharges
5
Q
chain of infection - means of transmission
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- in direct transmission, pathogen is passed to another without an intermediary
- usually requires fairly close association with infected host but not necessarily physical contact (ex; sneezing, coughing)
- most common respiratory/intestinal infections are passed directly
- transmission can also occur indirectly (animals & insects can serve as vectors = organisms that carry & transmit pathogen from one host to another)
- can also be transmitted via contaminated soil, food, water, inanimate objects
- some float in air for long periods & can travel long distances before they are inhaled
6
Q
chain of infection - portal of entry
A
- pathogens can enter one of three ways;
- direct contact or penetration of skin
- inhalation through mouth or nose
- ingestion of contaminated food or water
- agents that cause STIs enter through mucous membranes lining urethra (males) or cervix (females)
7
Q
chain of infection - new host
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- variety of factors determine whether pathogen will be able to establish itself & cause infection (number of pathogens is also important)
8
Q
immune system
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- body’s collective physical & chemical defences against foreign organisms & pathogens
- physical & chemical barriers = skin (body’s largest organ) prevents many microorganisms from entering body, few organisms can penetrate through skin without cut or break
9
Q
examples of physical & chemical barriers
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- mouth is lined with mucous membranes which contain cells to prevent passage of unwanted organisms & particles
- body openings & fluids that cover them (tears, saliva, vaginal secretions) are rich in antibodies & enzymes which break down & destroy microorganism
- respiratory tract is lined with mucous membranes & cells with hair-like protrusions called cilia (sweep foreign matter up & out of respiratory tract)
- particles not caught by cilia are expelled by cough (this is why smokers have chronic cough usually)
10
Q
white blood cells
A
- neutrophils = engulfs foreign organisms & infected, damaged, or aged cells (particularly prevalent during inflammatory response)
- macrophages = large phagocytic (cell-eating) cells that devour foreign particles
- natural killer cells = directly destroys virus-infected cells & cancer cells
- dendritic cells = specialized to active T & B cells
- lymphocytes = works in both bloodstream & lymphatic system
11
Q
two main lymphocyte cells
A
- T cells = arises in bone marrow & matures in thymus
- B cells = matures in bone marrow & produced antibodies
- helper T cells = help activate other T cells & may help B cells produce antibodies
- killer T cells = kill body cells that have been invaded by foreign organisms; also kill cells that have turned cancerous
- suppressor/regulatory T cells = inhibit growth of other lymphocytes
- memory T & B cells = generated during initial infection that circulate body for years, remembering specific antigens that caused infection & quickly destroy them if they appear again
12
Q
antibodies
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- specialized proteins produced by white blood cells that recognize & neutralize specific microbes
13
Q
antigens
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- markers on surface of foreign substance that immune system cells recognize as non-self & that trigger immune response
14
Q
inflammatory response
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- special cells in area of invasion or injury release histamine & other substances that cause blood vessels to dilate & fluid to flow out of capillaries into injured tissue
- this produces heat, swelling, & redness in affected area
- histamine = chemical responsible for dilation & increased permeability of blood vessels in allergic reactions
- white blood cells drawn to area & attack invaders
- pus = collection of dead white blood cells & debris resulting from encounter
15
Q
immune response
A
- two responses to invading pathogens; natural (innate) & acquired (adaptive)
- neutrophils, macrophages, dendritic cells, & natural killer cells part of natural response
- recognize pathogen as ‘foreign’ but have no memory of past infections → respond same way no matter how many times pathogen invades
- essentially eat invaders & destroy them internally, also destroy infected body cells
- T & B cells part of acquired response
- change after one contact with pathogen, developing memory for antigen
16
Q
immune response phase 1
A
- dendritic cells drawn to site of injury, consume foreign cells, & provide info about pathogen by displaying its antigens on their surface
- helper T cells read this info & rush to respond
17
Q
immune response phase 2
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- helper T cells multiple rapidly & trigger production of killer T cells & B cells in spleen & lymph nodes
18
Q
immune response phase 3
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- killer T cells & natural killer cells destroy infected body cells + B cells produce antibodies that bind to viruses & mark them for destruction by macrophages
19
Q
immune response phase 4
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- when danger is over, suppressor T cells halt immune response + memory B & T cells are reserved so that quick response can be mounted for future invasions by the virus
20
Q
immunity
A
- mechanisms that defend the body against infection; involves specific defences against specific pathogens (infected person will never get same illness again)
21
Q
acquired immunity
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memory lymphocyte’s ability to remember past infections & mobilize quicker, stronger response during subsequent encounters with same pathogen
22
Q
incubation
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- pathogens multiply in body, usually no symptoms are present (but person can be contagious)
23
Q
prodromal period
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- follows incubation, initial mild symptoms appear, “feeling a cold coming on”
- if immune system is strong or has acquired immunity, may eliminate pathogen before full-blown illness develops
24
Q
illness period
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- full-blown symptoms manifest as immune system actively fights off infection
25
contagion
- contagious before symptoms appear as pathogens multiply, symptoms may persist after pathogen is mostly destroyed, meaning one might still feel ill even when no longer infectious
26
immunization
- process of conferring immunity to a pathogen by administering a vaccine
- vaccine = preparation of killed/weakened microorganisms, inactivated toxins, or components of microorganisms that stimulate immune response without causing disease
- active immunity = vaccinated person produces their own antibodies to microorganism
- passive immunity = involves injecting antibodies produced by other humans or animals to provide temporary protection
27
types of vaccines
- live attenuated vaccines = contain weakened forms of pathogen (ex; measles, mumps, rubella)
- inactivated vaccines = contain killed pathogens that still stimulate immune response (ex; influenza)
28
allergies
- most allergic reactions due to production of special antibody called immunoglobulin E (IgE)
- initial exposure = sensitizes immune system by producing allergen-specific IgE, which binds to mast cells
- subsequent exposure = allergen binds to IgE on mast cells, releasing histamine & causing symptoms
- histamine = increases inflammation & mucus production, leading to symptoms like sneezing, congestion, itching, & swelling
29
anaphylaxis
- severe, systemic allergic reaction
- symptoms include swelling of throat, low blood pressure, heart arrhythmia, seizures, & can be life-threatening
- requires immediate injection of epinephrine
- people at risk should carry self-administrable epinephrine & wear MedicAlert identification
30
immunotherapy
- allergy shots to desensitize to specific allergens through gradually increasing doses over time
31
bacteria
- most abundant living organisms on Earth; microscopic single-celled organisms (bacterium, singular); about 100 bacterial species can cause disease in humans
- roles in ecosystems;
- decomposers = many bacteria feed on dead organic matter, recycling nutrients for other organisms
- pathogens = some bacteria feed on living hosts & can cause diseases
32
bacteria in human health
- friendly bacteria keep harmful bacteria in check by competing for food & resources & secreting substances toxic to pathogenic bacteria
- not all bacteria found in body are beneficial, however
- pathogenic bacteria in food or drink can disrupt normal harmony in intestines by invading cells or producing damaging toxins
33
pneumonia bacterial infection
- inflammation of lungs caused by bacteria, viruses, fungi, or chemical irritants
- symptoms; fever, chills, shortness of breath, increased mucus production, cough
- risk groups; infants under 2, elderly over 75, individuals with chronic health issues (heart disease, asthma, HIV)
- common cause is pneumococcus bacteria (vaccine available)
- can be treated with antibiotics
34
meningitis bacterial infection
- infection of meninges, (protective membranes covering the brain & spinal cord)
- symptoms; fever, severe headache, stiff neck, sensitivity to light, confusion
- viral meningitis; typically mild, self-resolving
- bacterial meningitis; life-threatening, requires immediate antibiotic treatment
- about 1000 cases annually in Canada, 11% fatality rate
- vaccination available but not effective against all strains
35
streptococcus (strep) bacterial infection
- red, sore throat with white patches on tonsils, swollen lymph nodes, fever, & headache
- spread through close contact with an infected person via respiratory droplets (sneezing or coughing)
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tuberculosis (TB) bacterial infection
- chronic infection primarily affecting the lungs
- about 1600 cases annually in Canada, with higher prevalence among Indigenous peoples & immigrants from endemic regions
- many strains respond to antibiotics but course of treatment lasts 6-12 months
37
ulcers
- 10% have ulcer at some point in their life (sore in lining of stomach or small intestine)
- caused by Helicobacter pylori or long-term NSAID use
- symptoms; abdominal pain, nausea, loss of appetite
- treatment; antibiotics for H. pylori infections
38
other bacterial infections
- tetanus = caused by Clostridium tetani, leading to muscle stiffness & spasms (preventable by vaccination)
- C. diff (Clostridium difficile) = causes diarrhea to life-threatening colitis, often in healthcare settings (NAP1 strain is highly virulent & antibiotic-resistant)
- pertussis (whooping cough) = caused by Bordetella pertussis, characterized by severe coughing fits (preventable by vaccination)
- Urinary Tract Infections (UTIs) = mostly caused by Escherichia coli, common in sexually active women
39
epidemic vs endemic
- epidemic = occurrence in a particular community or region of more than the expected number of cases of a particular disease
- endemic = persistent & widespread presence of a disease in a population
40
antibiotics
- synthetic or naturally occurring substances used as drugs to target & kill bacteria
- most work by interrupting production of new bacteria, either by damaging part of their reproductive cycle or causing production of faulty parts in new bacteria
- penicillin inhibits formation of cell wall during bacterial cell division
- other antibiotics inhibit protein production or interfere with genetic material (DNA) during bacterial reproduction
- also kill good bacteria as they eliminate harmful ones
41
types of antibiotics
- penicillin & its derivatives
- protein synthesis inhibitors
- DNA synthesis inhibitors
42
antibiotic resistance
- caused by misuse or overuse of antibiotics
- resistance can also develop due to genetic mutations or the transfer of resistance genes between bacteria
- consequences;
- resistant bacteria can grow & flourish when exposed to antibiotics, while sensitive bacteria die off
- entire colonies of bacteria can become resistant to one or more antibiotics, making infections difficult to treat
43
examples of resistant bacteria
- resistant strains of gonorrhea
- resistant strains of salmonellosis (food-borne illness)
- one strain of tuberculosis is resistant to seven different antibiotics
44
factors promoting resistance
- frequent exposure to antibiotics
- not completing the full course of an antibiotic
- using antibiotics for viral infections
- extensive use of antibiotics in agriculture, leading to transmission of resistant bacteria from animals to humans
45
infectious disease
- caused by infection, when a microorganism (bacteria, virus, fungi, protozoan) invades body of a host; typically accompanied by damage to cells
- exposer to pathogen is followed by latent period → time between infections & development of symptoms/signs (can vary from few hours to many years, typically several days long
46
how an infection is caught
- people = direct (kissing, hugging) & indirect contact (surfaces)
- food = ex; Salmonella from raw or undercooked food
- water = contaminated water can carry pathogens
- animals & insects (vector transmission) = mosquitoes, rats/fleas
47
lines of defence
- first line of defence = skin, cilia, mucus, elevated body temperature, cough, tears, saliva
- second line of defence = immune cells recognize pathogens as foreign because pathogens have antigens ‘chemical structures’ (ex; proteins/sugars) on their surface that are different from your own
- specialized cells including macrophages, T cells, & B cells launch immune response to eliminate the pathogen
