Pulmonary defence mechanisms Flashcards
(28 cards)
Approximately, how many L of air needs to be inhaled to consume the 500 L of oxygen required?
8000L
What is the 500 L of oxygen used for ?
Produce energy (Oxidative phosphorylation)
Used for basal metabolic rate
Physical activity
WHat potential damaging Things?? exist in the air
- Microorganisms – bacteria, viruses, fungi, helminths
- Allergens – dust, pollen
- Organic particles – occupational exposures, pollution
- Toxic gases – carbon monoxide, sulphur dioxide, nitrogen dioxide
What size / types of particles can air contain?
Large particulates
- Foreign body aspiration (e.g. food, liquid, choke hazards)
Fine particulate material
- Pollution (<2.5 - 1000 μm)
- Dust (0.1-1000 μm)
- Pollen (10 - 100 μm)
Microscopic pathogens
- Fungal spores (2 - 10 μm)
- Bacteria (0.5 - 5 μm)
- Viruses (< 1 μm)
Why are nanoparticles from diesel exhaust particularly damaging ?
Able to reach lower parts pf respiratory system due to small size
List the physical defence mechanisms of the respiratory system
- Large scale
-nasal hairs - nasal turbinates
- branching airway structure.
- Micro scale = cilia, mucus
Name some protective reflexes of the respiratory system
Coughing
Sneezing
Expiratory reflex
How is the lung adadted to provide defence on an immunological scale?
- Lung resident immune cells (alveolar macrophages)
- Antimicrobial proteins
- Structural cells (epithelial cells)
What are nasal turbinates?
Mucous membrane-lined ridged structures that help to warm and humidify air before it reaches airways/lungs
helps filter out particles larger than ≈ 2μm
What has decreased nasal hair density/ mouth breathing been linked to ?
Asthma risk/morbidity
Shows protective effect of adaptations
What type of cell line the respiratory tract from the trachea to terminal bronchioles?
Ciliated epithelium
What does mucus colouration indicate ?
What causes the colour?
Respiratory infection
Due to presence and breakdown of granulocytes
What causes changes to mucus viscosity?
Breakdown/shedding of surrounding epithelium (presence of stiicky DNA + cell debris)
Or
Mucus dehydration/poor clearance (cystic fibrosis)
How is the level of mucus modulated?
Parasympathetic innervation
via cholinergic activation of submucosal glands
Which receptors are triggered by chemical stimuli
(causing physical reflex)
Nociceptors
Explain the process of sneezing
Stimulation of sensory receptors within nasal cavity
- deep inspiration phase
- compression phase (glottis is closed)
- expiration phase
How is coughing initiated
What does it involve
Triggered by stimulation of receptors within larynx and large airways
bronchoconstriction to further increase expulsion pressure.
What is the laryngeal reflex?
Short, forcible expiratory effort
triggered by stimulation of sensory receptors within vocal folds
What is the purpose of the laryngeal reflex ?
To prevent foreign bodies entering the airways
To expel phlegm
How is the laryngeal reflex different from coughing?
Does not have an inspiration phase
An initial inspiration before expiration (such as with coughing) is undesired in some circumstances as it could potentially lead to inspiration pneumonia.
How does the branching structure of the airways helps to filter out the particles?
inhaled air reaches an airway branching site, airflow changes from laminar to semi-turbulent flow pattern, increasing particle deposition as more particles come into contact with the mucus-lined airway wall.
What provides the last line of defence?
Resident immune cells
Describe alveolar macrophages
Resident phagocytes of lung
Develop in bone marrow
Travel to lungs
Which immune system are AMs part of?
Innate immune system
