Lecture 5 - Physiology of the airway Flashcards
What nerve is afferent in pharyngeal dilator refleves
Trigeminal nerve - 5th cranial nerve
Efferent nerve in pharyngeal dilator reflexes
vagus nerve - 10th cranial nerve
What occurs during pharyngeal dilation in the upper airway
pressure receptors in the brain stem respond to afferent fibres and cause efferent fibres to cause pharyngeal muscle contraction
Sleep disordered breathing causes
snoring - 25%
sleep apnoea - 10% (pauses in breathing during sleep due to an obstruction)
Clinical features of sleep disordered breathing
snoring sleep daytime somnolence ( sleepiness)
What is sleep disordered breathing associated with
obesity and hypertension
Treatment for sleep disordered breathing
weight loss
CPAP (continuous positive airway pressure) - sleep apnoea
used during sleep to avoid obstruction
What keeps the airway open
continuous muscle activity
reflex control of the muscles
When is control of the muscles poor
during sleep or with sedative drugs
Airway lining the fluid histology
Ciliated epithelial cells and goblet cells
Nose and pharynx has
pesudostratified cells
Trachea and bronchi have
columnar cells
Bronchioles have
cuboidal cells
What is airway lining fluid produced by?
ciliated epithelial cell and goblet cells
What do the ciliated epithelial and goblet cells produce?
mucin granules
when is mucin produced
in response to airway irritation
tobacco smoke
infection
Lining of the airways
columnar cells, periciliar layer (salt and water) and mucous layer
what does the periciliar layer do
removes particles we dont want captured by the mucus up the airway away from the lungs
What motion does the cilia use to move the mucus?
periciliar layer allows them to move it.
What effects the strokes of the cilia
tobacco smoke
inhaled anaesthetics
air pollution
infections
what function does the airway lining fluid perform
humidification
- nose breathing better than mouth breathing
- affected by breathing pattern (at rest and at exercise)
- heat and moisture exchanger
active control of pericilary layer to move mucus .
low humidity - less mucus
high humidity - more mucus
how does lining help in airway defence?
Muco-ciliary escalator
mucus and cilia moving things out
expectoration - coughing
What is cystic fibrosis
Autosomal recessive inheritance
1 in 2500 births
Abnormal cystic fibrosis transmembrane regulator protein (sodium chloride channel)
Progressive lung infection and destruction
affects all systems with epithelial surfaces (GI, Genital, urinary)
What happens when very large particles are inhaled
Deposited in the nose and pharynx. has an inertial impact (resistance of any physical object)
examples pollen and sawdust
What happens to large particles
deposited in the large airways
inertial impaction
fungal spores
What happens to small particles in the airway
deposited in the bronchioles
through sedimentation
particulate pollution, stone dust, asbestos
what happens to very small particles in the airway
it is exhaled through diffusion
eg. smoke
What affects the fate of inhaled particles apart from size
humidity in the inspired gas
how do inhaler particle size relate to drug delivery system? in the future
size related to site of action in the airway
Large - hay fever
medium - ashtma, COPD
small - absorption in the blood
What are non-immunological defences
- physical barrier and removal
- chemical inactivation
-lysosome
protease enzyme eg. elastase and anti-protease
-antimicrobial peptides eg. human B defensins - Alveolar macrophages (ingest them)
What are immunological defences?
2 types: Humoral and cell mediated
How does humoral immunity work?
IgA - nose and large airways
IgG - small airways
IgE - allergic disease
Actions:
inhibits binding of pathogens to epithelial cells
complement activation
recruitement of immune cells
What is cell mediated immunity?
epithelial cells
macrophages
Pathology:
neutrophils - infection
eosinophils - allergy
