Airway physiology Flashcards
Which 2 main muscles keep the airway open?
Genioglossus and the tensor palati
Which two nerves are involved in the pharyngeal dilator reflex?
Trigeminal nerve (afferent: pressure receptors –> brain stem) and vagus nerve (efferent: brain stem –> pharyngeal muscle contraction)
Why does snoring occur?
The brain is not active enough to keep the airway fully open so the soft pallate flaps against the pharynx
What is sleep apnoea?
The airway is not open at all for a time so trouble breathing and deep sleep is impossible. Adrenaline is released when can’t breathe which can lead to hypertension etc.
What are two treatments for sleep disordered breathing?
Weight loss and CPAP (continuous positive airway pressure)
What is required to keep the airway patent?
Continuous muscle activity
Which cells produce airway lining fluid?
Goblet cells
What three things might cause excess mucin granules (mucus) to be released?
Airway irritation, tobacco smoke, infection
What structures move the mucus through the lungs?
Cilia
What are four things that inhibit the movement of cilia?
tobacco smoke, inhaled anaesthetics, air pollution, infections
Why does smokers cough get worse at night/early morning?
Smoking paralyses the cilia, no cigarettes for a time overnight so the cilia start to recover which mobilises the mucus and causes the cough. Another cigarette in the morning paralyses them again and makes the cough better.
What are two functions of airway lining fluid?
- humidification
2. airway defence (bacteria is trapped in the mucus and escalated (muco-ciliary escalator) for expectoration)
Which protein is affected in cystic fibrosis?
CFTR (cystic fibrosis transmembrane regulator)
What are the two layers of airway lining fluid?
Periciliary and mucous
Where are inspired particles >8µm deposited and by what mechanism?
Nose and pharynx by inertial impaction
Where are inspired particles 3-8µm deposited and by what mechanism?
Large airways by inertial impaction
Where are inspired particles 0.5-3µm deposited and by what mechanism?
Bronchioles by sedimentation
Where are inspired particles >0.5µm deposited and by what mechanism?
They are fully inhaled and exhaled, diffusion
Where in the respiratory tract would you want an inhaled hayfever drug to be deposited, and so what size particle would you want?
In the pharynx and large airways, so a large particle size >5µm
Where in the respiratory tract would you want an inhaled asthma/COPD drug to be deposited, and so what size particle would you want?
In the small airways, so medium sized particle about 1-3µm
Where in the respiratory tract would you want an inhaled drug to be deposited if you want it to be absorbed into the blood? What is a potential use for this and what sized particle is needed?
Alveoli, potential for insulin inhaler for diabetics, very small particle size 0.5-1µm
What are the two types of pulmonary defence?
Non immunological and immunological
What are the 3 components of non-immunological pulmonary defence?
- Physical barrier and removal
- Chemical inactivation
- Macrophages
What are 3 possible defences in the chemical inactivation non-immunological response?
- Lysozymes
- Protease enzymes (e.g. elastase)
- Antimicrobial peptides (e.g. human beta defensins)
