Infection - Innate Immunity Flashcards Preview

CJ: UoL Medicine Semester Two (ESA2) > Infection - Innate Immunity > Flashcards

Flashcards in Infection - Innate Immunity Deck (37)
Loading flashcards...

What is the difference between infectivity and virulence?

Infectivity is the capacity of a pathogen to establish itself within a host. Virulence is the capacity of a microbe to damage the host


Define immune system

Cells and organs that contribute to immune defences against infectious and non-infectious conditions


Define infectious disease

When the pathogen succeeds in evading and/or overwhelming the host's immune defences


What are the four main roles of the immune system?

- pathogen recognition
- containing/eliminating the infection
- regulating itself
- remembering pathogens


Describe some key differences between innate and adaptive immunity

Innate immunity:
- fast (seconds)
- lack of specificity and memory
- no change in intensity

Adaptive immunity:
- slow (days)
- specific
- has immunologic memory
- changes in intensity


What are 'barriers' in immunity?

Factors that prevent entry and limit growth of pathogens


Give some examples of physical barriers in innate immunity

- skin
- mucous membranes (mouth, respiratory tract, GI tract, urinary tract)
- bronchial cilia


Give some examples of physiological barriers in the innate immune system

- diarrhoea
- vomiting
- coughing
- sneezing


Give some examples of chemical barriers in the innate immune system

- low pH (skin is 5.5, stomach is 1-3, vagina is 4.4)
- antimicrobial molecules


Give some examples of antimicrobial molecules that form part of the innate immune system

- IgA (tears, saliva, mucous membrane)
- lysozyme (sebum, perspiration, urine)
- mucus (mucous membranes)
- beta-defensins (epithelium)
- gastric acid and pepsin


What are 'biological barriers'?

Non-pathogenic normal flora found in strategic locations, eg. nasopharynx, mouth/throat, skin, GI tract, vagina. They are not found within internal organs/tissues


Give some benefits of the body having 'normal flora' (non-pathogenic microbes)

- compete with pathogens for attachment sites and resources
- produce antimicrobial chemicals
- synthesise vitamins (K, B12, other B vitamins)


Give some examples of normal flora that inhabit the skin

- staphylococcus aureus
- staphylococcus epidermidis
- streptococcus pyogenes
- Candida albicans
- clostridium perfringens


Give some examples of normal flora that inhabit the nasopharynx

- streptococcus pneumoniae
- neisseria meningitidis
- haemophilus species


How could normal flora be displaced from its normal location to a sterile location?

- breaching skin integrity (skin loss, surgery, injected drugs, IV lines)
- faecal-oral route (foodborne infection)
- fecal-perineal-urethral route (UTI infection)
- poor dental hygiene/dental work


Which groups of patients are seen as high risk for infections from normal flora?

Patients who are/have:
- asplenic/hyposplenic
- damaged or prosthetic valves
- previous infective endocarditis


Give some examples of conditions that may cause a host to become immunocompromised, allowing overgrowth of normal flora

- diabetes
- malignant diseases
- chemotherapy


What is thrush caused by?

Vaginal yeast infection (candida albicans) that can occur when normal flora is depleted by antibiotics


What are macrophages?

Phagocytes which are present in all organs. They ingest and destroy microbes via phagocytosis, and present microbial antigens to T cells (part of adaptive immunity). They produce cytokines/chemokines


What are monocytes?

Phagocytes which are present in the blood. They are recruited at the infection site where they differentiate into macrophages


What are neutrophils?

Phagocytes which make up 60% of blood leukocytes. They are increased during infection, when they are recruited by chemokines. They ingest and destroy pyogenic bacteria


What is the function of basophils/mast cells?

Early actors of inflammation (vasomodulation) which are important in allergic responses


What are eosinophils used for?

Defence against multi-cellular parasites (worms)


What are natural killer cells for?

They kill all abnormal host cells (either infected with virus or malignant)


What are dendritic cells for?

Present microbial antigens to T cells (in acquired/adaptive immunity)


How does the phagocyte recognise the pathogen to be consumed?

Pathogen will have microbial structures (pathogen-associated molecular patterns or 'PAMPs') and phagocyte has pathogen recognition receptors


What is opsonisation of microbes?

Coating proteins called opsonins bind to the microbial surfaces, leading to enhanced attachment of phagocytes


Give some examples of opsonins

- complement proteins (C3b, C4b)
- antibodies (IgG, IgM)
- acute phase proteins (C-reactive protein and mannose-binding lectin)

These are all essential in clearing encapsulated bacteria


What are the two phagocyte intracellular killing mechanisms?

- oxygen dependent pathway
- oxygen independent pathway


What is the oxygen-dependent killing pathway?

Reactive oxygen-containing molecules are produced by the phagocyte which are anti-microbial

Decks in CJ: UoL Medicine Semester Two (ESA2) Class (87):