Lecture 5 - Physiology of the airway

Question 1

What nerve is afferent in pharyngeal dilator refleves

Answer 1

Trigeminal nerve - 5th cranial nerve

Question 2

Efferent nerve in pharyngeal dilator reflexes

Answer 2

vagus nerve - 10th cranial nerve

Question 3

What occurs during pharyngeal dilation in the upper airway

Answer 3

pressure receptors in the brain stem respond to afferent fibres and cause efferent fibres to cause pharyngeal muscle contraction

Question 4

Sleep disordered breathing causes

Answer 4

snoring - 25%

sleep apnoea - 10% (pauses in breathing during sleep due to an obstruction)

Question 5

Clinical features of sleep disordered breathing

Answer 5

snoring sleep 
daytime somnolence ( sleepiness)

Question 6

What is sleep disordered breathing associated with

Answer 6

obesity and hypertension

Question 7

Treatment for sleep disordered breathing

Answer 7

weight loss
CPAP (continuous positive airway pressure) - sleep apnoea
used during sleep to avoid obstruction

Question 8

What keeps the airway open

Answer 8

continuous muscle activity

reflex control of the muscles

Question 9

When is control of the muscles poor

Answer 9

during sleep or with sedative drugs

Question 10

Airway lining the fluid histology

Answer 10

Ciliated epithelial cells and goblet cells

Question 11

Nose and pharynx has

Answer 11

pesudostratified cells

Question 12

Trachea and bronchi have

Answer 12

columnar cells

Question 13

Bronchioles have

Answer 13

cuboidal cells

Question 14

What is airway lining fluid produced by?

Answer 14

ciliated epithelial cell and goblet cells

Question 15

What do the ciliated epithelial and goblet cells produce?

Answer 15

mucin granules

Question 16

when is mucin produced

Answer 16

in response to airway irritation
tobacco smoke
infection

Question 17

Lining of the airways

Answer 17

columnar cells, periciliar layer (salt and water) and mucous layer

Question 18

what does the periciliar layer do

Answer 18

removes particles we dont want captured by the mucus up the airway away from the lungs

Question 19

What motion does the cilia use to move the mucus?

Answer 19

periciliar layer allows them to move it.

Question 20

What effects the strokes of the cilia

Answer 20

tobacco smoke
inhaled anaesthetics
air pollution
infections

Question 21

what function does the airway lining fluid perform

Answer 21

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

Question 22

how does lining help in airway defence?

Answer 22

Muco-ciliary escalator
mucus and cilia moving things out
expectoration - coughing

Question 23

What is cystic fibrosis

Answer 23

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)

Question 24

What happens when very large particles are inhaled

Answer 24

Deposited in the nose and pharynx. has an inertial impact (resistance of any physical object)
examples pollen and sawdust

Question 25

What happens to large particles

Answer 25

deposited in the large airways
inertial impaction
fungal spores

Question 26

What happens to small particles in the airway

Answer 26

deposited in the bronchioles
through sedimentation
particulate pollution, stone dust, asbestos

Question 27

what happens to very small particles in the airway

Answer 27

it is exhaled through diffusion

eg. smoke

Question 28

What affects the fate of inhaled particles apart from size

Answer 28

humidity in the inspired gas

Question 29

how do inhaler particle size relate to drug delivery system? in the future

Answer 29

size related to site of action in the airway
Large - hay fever
medium - ashtma, COPD
small - absorption in the blood

Question 30

What are non-immunological defences

Answer 30

2. physical barrier and removal
3. chemical inactivation
   -lysosome
   protease enzyme eg. elastase and anti-protease
   -antimicrobial peptides eg. human B defensins
4. Alveolar macrophages (ingest them)

Question 31

What are immunological defences?

Answer 31

2 types: Humoral and cell mediated

Question 32

How does humoral immunity work?

Answer 32

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

Question 33

What is cell mediated immunity?

Answer 33

epithelial cells
macrophages

Pathology:
neutrophils - infection
eosinophils - allergy