Acute Respiratory Infecitons And Pneumonia Flashcards
What are the anatomical defences in the respiratory tract?
Nose hairs which filter particles
Nasal conchae which rapidly humidify and warm air
Epithelial linings
Cilia
What are the mechanical defences in the respiratory tract?
Coughing and sneezing reflex
Mucociliary escalator
What is the mucociliary escalator?
Pseudostratified columnar epithelia has a lining of cilia, with a mucous layer overlying on top. The cilia co-ordinate the beating to clear mucus upwards before reaching the lungs. It is present in the nose, bronchi.
-> This can become damaged by inflammation, particularly worse in smoking.
What are the immune mediated defences in the respiratory tract?
Innate immune defences, including
Antimicrobial peptides, macrophages, and inflammatory cells.
Adaptive immune defences including,
Lymphocytes specific to the pathogen.
What are the nasal turbinates?
Also known as the nasal conchae, they are shelves of bone in the lateral walls of the nasal cavity which can trap large particles. It serves to direct the flow of air, warming and humidifying it as air passes through.
The superior and middle are projections of ethmoid bone. The inferior concha is a separate bone.
What is the histology of the nasal cavity?
Lamina propia
Goblet cells
Pseudostratified columnar epithelia
Basal cells
Bowman’s gland
Which structure produces nasal secretions?
Goblet cells produce the mucus nasal secretions containing antimcirobial enzymes such as anti-proteases, alpha-1 trypsin and lysozymes. Immune cells such as IgA are present here.
What is the histology of the respiratory tract?
Pseudostratified columnar epithelia which contains tight junctions that prevent pathogen entry and goblet cells to produce mucus. It is lined with cilia which moves mucous in the sol phase for the mucocilary escalator movement
Which conditions impair the functioning of the mucociliary escalator?
Cystic Fibrosis
Primary ciliary dyskinesia.
What is cystic fibrosis?
Genetic condition caused by deficiency in the CFTR gene encoding for the CFTR Cl- ion channels for Cl- secretion that affects water transport for mucus fluidity. This causes mucus to harden over the epithelia of the tract and cause damage, commonly resulting in Bronchieactasis where the airways widen due to damage.
What is primary ciliary dyskinesia?
Cilia has absence of dynein arm which connects microtubules together and contains ATPase for energy breakdown. This means cilia is unable to move and beat for the mucociliary escalator, resulting in recurrent upper respiratory tract infections, sinusitis and Bronchieactasis. It can result in dextrocardia, where the heart is on the right side.
Cilia are present in the sperm and ovum and this can result in infertility.
What is the role of alpha-1 trypsin?
Protease inhibitor which protects the nasal cavity and lungs from proteolytic damage due to the inflammatory microbicidals like elastase released by neutrophils and macrophages during infection.
What is emphysema?
“Pink puffers”
Damage to the alveoli which limits elastic recoil and gas exchange in the lungs. This occurs due to chronic inflammation, which may occur when there is a deficiency of alpha-1 anti trypsin that mediates lung damage from immune cell action. They generally have pursed lips.
What is PRRS?
Pathogen recognition receptors: Germ-line encoded receptors which we inherit and express on immune cells and epithelia to recognise both PAMP (pathogen associated molecular patterns) and DAMP (damage associated molecular patterns) for innate immunity.
Induces chemokine and cytokine production.
What is a PAMP?
Pathogen associated molecular pattern, highly conserved sequence part of the structure that a pathogen requires in order to survive.
What are toll-like receptors?
Pathogen recognition receptor type that can differentiate between microbial classes and initiate the innate immune response.
What is humoural immunity?
Immune defences due to antibodies produced by B lymphocytes. In the upper airways, this is mainly via IgA present in mucus.
IgG and IgM travel via the bloodstream.
IgG is present in the alveoli.
Where is IgA found?
Mucus
Where is IgE found?
Tissues
Where is IgM found?b
Bloodstream.
Where is IgG found?
Bloodstream.
Where is IgD found?
Surface of B lymphocytes, as an antigen receptor.
What is cell mediated immunity?
Type of adaptive immunity generated by macrophages and T lymphocytes against Intracellular pathogens, which includes cytotoxic T cells.
What is commensalism?
Relationship where one organism benefits and the other is unaffected.
What are the opportunistic pathogens of the upper respiratory tract?
Streptococcus pneumonia
Staphylococcus aureus
Haemophilius influenza
Maraxella catarrhalis
-> These are part of the normal flora of the URT and when the immune system defences are lowered, they can colonise and cause infection.
Which part of the respiratory tract is more prone to infection?
Upper respiratory tract
-> Lower respiratory tract contains macrophages which provide an effective defence via phagocytosis.
What is the leading cause of death in infectious diseases?
Lower respiratory tract diseases.
What does marexella catarrhaxis cause?
Gram negative diplococcus bacteria which is part of the normal flora of the URT and typically causes otitis media in children and sinusitis in adults. It is treated with amoxicillin.
