Physiology of the airway Flashcards
When the mouth is open for breathing- what muscles contract and relax
- Tongue contracted
- Pharynx is relaxed
- Flops backwards when breathing
- Tonic and phasic muscle activity
What is phasic activity?
dPhasic activity that happens as phases- inspiration/ expiration
What is tonic activity?
Tonic is when it happens all the time
What is the pharyngeal dilator reflex?
Airway has pressure receptors that detect when P drops- by airway being too narrow. Pressure receptors to brain stem via afferent (trigeminal nerve). Brain to pharyngeal muscle contraction via efferent (vagus nerve).
Sleep disordered breathing- snoring
Snoring (25%)- when the reflex isn’t working well enough- Snore is soft palete flapping backwards and forwards very quickly
Sleep disordered breathing- apnoea
Sleep apnoea (10%)- lack of breathing- airway blocks and air can’t get through- number of times a person stops breathing per hour
Sleep disordered breathing- clinical features
Clinical features: • Snoring • Daytime somnolence • Associated with: -obesity- related to sleep apnoea- can diagnose with the size of the neck as more fat tissues in the neck -hypertension
Sleep disordered breathing- treatment
Treatment:
• Weight loss
• CPAP- continuous positive airway pressure- keeps air at a higher P than atm P
When are the control of the muscles often poor
During sleep or with sedative drugs
What is airway lining fluid produced by?
Epithelial and goblet cells
What do goblet cells produce?
Goblet cells- produce mucus – present in large number in the airways
Mucin protects the lungs.
Goblet cells release mucin granules.
What are mucin granules released in response to?
- airway irritation
- tobacco smoke
- infection
How many layers do cilia cells have?
What is the lower layer made of?
Movement- 2 layers- periciliary and mucous
Periciliary layers (salt layer)- water with salt
What is cilia inhibited by?
- Tobacco smoke
- Inhaled anaesthetics
- Air pollution
- Infections
How do cilia cells working?
Recovery and effective stroke of cilia cells.
Muco-ciliary escalate- pushing against gravity- towards the larynx so that you can get cough it out
Airway lining fluid- function- humidification
- Nose breathing better than mouth breathing
- Affected by breathing pattern
- Heat and moisture exchanger- when dry air passes the fluid water evaporates into the gas mixture. Cause the heat from the fluid to be lost. When air is expired the warm air heats up the lining fluid causing condensation. If this exchange didn’t occur, litres of water would be lost from expired air.
- ‘Active’ control of periciliary layer
Airway lining fluid- function- airway defence
- Muco-ciliary escalator
* Expectoration- coughing out mucus which have moved up the top of the airway
Why is nose breathing better than mouth breathing?
Nose breathing better than mouth breathing as air has further to go and there is less turbulence - more air comes into contact with mucus so better humidified
To humidify- water evaporates from the linings
What does the perciliary secrete?
Periciliary layer secretes chloride, decreasing water potential, causing water to move in via osmosis- controlling water loss- gel layer thickness controls water loss
What are the clinical features of CF?
- Autosomal recessive inheritance
- (1 in 2500 births)
- Abnormal cystic fibrosis transmembrane regulator protein
- Progressive lung infection and destruction
- Affects all systems with epithelial surfaces
How does CF occur?
CFTR protein on epithelial cells that controls the airway lining fluid
Mutation of the CFTR gene can lead to CF- some mild, some severe
Inhaled particles- very large ones
Deposited- Nose and pharynx
Mechanism- Inertial impaction
Examples- Pollen and sawdust
Inhaled particles- large ones
Deposited- Large airways
Mechanism- Inertial impaction
Examples- Fungal spores
Inhaled particles- small ones
Deposited- Bronchioles
Mechanism- Sedimentation
Examples- Particulate pollution, stone dust, asbestos