Host defence in the lung Flashcards
what is our main defence in the lung against infection?
inflammation.
how does acute inflammation occur? [3 steps]
- vasodilation leads to exudation of plasma including antibodies.
- activation og biological cascades.
- migration of blood leukocytes into the tissues.
What is the specialist macrophage in the lung?
the alveolar macrophage.
What is the difference between chronic and acute inflammation?
any of these; Causative agent, Cells involved in response, onset, duration, outcomes.
why are macrophages described as a spectrum?
they can develop into many cells and can swap their phenotype.
What are the three main functions of the alveolar macrophage?
- Microbial killing
- co-ordination of the inflammatory response [cytokine production]
- induction and clearance of apoptotic cells.
What is meant by neutrophil apoptosis?
once the neutrophils have reached their target area and done their job they need to be removed to stop accumulation this is done via apoptosis [programmed cell death].
How do neutrophils migrate to a source of infection?
they can detect concentration gradients and move along it by moving its receptors to the leading edge.
how is the phagolysosome created?
by membrane invagination by the neutrophil and pinching phagosome fusion with granules.
What 3 steps allow a neutrophil to enter a cell?
- Margination with the help of selectins.
- adhesion to the membrane with the help of integrins.
- changes in structure of endothelium and in the neutrophil.
what is the role of respiratory epithelium?
to moisten and protect the airways. To protect and prevent pathogens from reaching the deep alveolar tissue, can be done by releasing mucus.
What types of molecules are included in the mucus that help to protect the lung?
water, carbs, proteins and lipids?
what molecules are secreted by the epithelium that play a role in host defence?
antiproteases, anti-fungal peptides, Surfactant.
What type of stratified epithelia is there in; 1.bronchus, 2. bronchioles, 3. alveolar.
- columnar
- cuboidal
- squamous
what is the much-cillary escalator?
the synchronised beating movement of the cilia which creates directional waves to move mucus up the airway.
What is a cough?
it is an expulsive reflex that protects the lung and respiratory passages from foreign bodies.
what is a sneeze?
a sneeze is the involuntary expulsion of air containing irritants from the nose.
why do infections usually occur at ciliated epithelia?
they have a larger surface area than all of the other airway epithelia.
how may a obstructive disease occur from through defence in the lung?
an abnormal response from airway epithelia to injury. e.g continuous large amounts of mucus released.
What is the difference between innate and adaptive immunity?
innate is non specific defence mechanisms that are immediate. Adaptive refers to antigen specific defence that isn’t necessarily immediate.
Describe how alveolar macrophages are ‘antigen presenting cells’
They ‘taste’ the environment, phagocytose foreign material and present the foreign antigen on their surface to stimulate other cells.
Why are lymphocytes and T cells called ‘effector cells’ ?
they recognise the antigen presenting macrophages and destroy them through immunoglobulins or T killer cells.
what is the basis of diversity In adaptive immunity?
It is the generation of pathogen-specific recognition regions in lymphocyte regions. [occurs via VDJ recombination]
What is meant by immune tolerance?
the state of unresponsiveness of the immune system, this can be to self or to pathogens?
why is it essential to have tolerance?
without tolerance then an individual would be likely to develop an auto immune disease such as diabetes.
What are the two main types of T cells?
- CD8 positive cytoxic cells - kill virally infected or cancer cells.
- CD4 positive T helper cells - produce cytokines to regulate other innate and adaptive defences.
what are the characteristics of IgM?
It is produced early in immune response.
Opsonization, agglutination and complement activation.
What are the characteristics of IgA?
It is found in tears, saliva and breast milk.
Resistant to proteases.
mucosal immunity [gut, lung]
What are the characteristics of IgG?
> 80% of antibodies are IgG.
Cytotoxicity, neutralises toxins
opsonisation and complement activation.
placental transfer to foetus
What are the characteristics of IgD?
Found on the surface of B cells.
Development of the immune response
What are the characteristics of IgE?
they attach to mast cells.
they mediate allergic reactions.
What do mast cells release?
Histamine.
PDG2, proteases, cytokines, IL’s
what is a typical type 1 hypersensitivity reaction?
Anaphylaxis to food or drugs.
what is the third type of hypersensitivity?
the creation of immune complexes and the activation of complementing molecules.
List 5 environmental influences of lung disease.
Pollens, Infectious agents, Fungi, Pets, Animals, Air pollution.
List 5 occupational influences on lung disease.
Flour, Car paint, Resins, Cleaning products, Wood dusts, Animal lab workers.
What are the two forms of hypersensitivity pneumonitis?
Acute and Sub-Acute.
What type of disease is hypersensitivity pneumonitis?
It is an immune complex disease; antigen reacts with antibody and creates an IgG response. Very specific environmental influences.
What is COPD?
Chronic obstructive pulmonary disease, a long term progressive lung disease where lung capacity significantly decreases.
