Sensory Aspects of Respiratory Symptoms

Question 1

Describe the pathway from stimulus to evoked sensation? What are the names for the two main parts of this?

Answer 1

Stimulus - transducer - excitation of sensory nerves - integration of CNS - sensory impression
This is NEUROPHYSIOLOGY
Sensory impression - perception - evoked sensation
This is BEHAVIOURAL PSYCHOLOGY

Question 2

Describe the distribution of rapidly adapting irritant receptors within the airway epithelium.

Answer 2

They are most numerous on the posterior wall of the trachea and in the main carina.
They decrease in number as you go down the airways and they are absent in the bronchioles.
They are commonly found at the branch points of large airways.

Question 3

What are the three main types of sensory receptors in the lungs and airways?

Answer 3

C-fibre receptor
Slowly adapting stretch receptors
Rapidly adapting stretch receptors

Question 4

Which nerve do all the sensory receptors in the lungs and airways pass through?

Answer 4

Vagus nerve

Question 5

What is used as a stimulus for the C-fibres?

Answer 5

Caspaicin

Question 6

What stimulates C-fibres?

Answer 6

Chemicals

Question 7

What do the rapidly and slowly adapting stretch receptors respond to?

Answer 7

Inflation (increase in tracheal pressure)

Question 8

Describe the differences between the three types of sensory receptor.

Answer 8

C-fibres are unmyelinated whereas the other two are myelinated.
C-fibres are found in the larynx, trachea, bronchi and lungs
Rapidly adapting stretch receptors are found in the naso-pharynx, larynx, trachea and bronchi
Slowly adapting stretch receptors are located on airway smooth muscle, mainly in the trachea and main bronchi

Question 9

What are the two broad types of sensory receptor in the airways?

Answer 9

Mechanoreceptors

Nociceptors

Question 10

Other than mechanical displacement, what else activates the mechanoreceptors?

Answer 10

Citric acid

Question 11

What is the collection of neurons in the cough centre called?

Answer 11

Nucleus tractus solitarius

Question 12

What is this collection of neurons connected to?

Answer 12

Medullary cough pattern generator

Question 13

What is the role of the cerebral cortex in the complete cough pathway?

Answer 13

The cerebral cortex is needed to generate a cough and generate the urge to cough. When asleep, this component of the complete cough pathway is inhibited so a certain degree of wakefulness is needed to cough. General anaesthetic also inhibits this.

Question 14

What are the three phases of cough?

Answer 14

Inspiratory phase
Glottic closure
Expiratory phase

Question 15

What is acute cough and what is it usually caused by?

Answer 15

Cough that lasts less than 3 weeks

It is commonly caused by rhinovirus

Question 16

What are the causes of chronic cough?

Answer 16

Asthma
Gastrooesophageal reflux
Rhinosinusitis
Chronic bronchitis
Bronchiectasis

Question 17

What is another name for chronic cough? How can the sensitivity be tested?

Answer 17

Cough hypersensitivity syndrome
Giving patients increasing concentrations of caspaicin until they cough. People with cough hypersensitivity syndrome will have relatively low tolerance of caspaicin.

Question 18

What drugs can inhibit the cortical control of the cough reflex?

Answer 18

Opiates

Question 19

Sensory perception from the nose and the pharynx goes through which nerves?

Answer 19

Nose - trigeminal

Pharynx - glossopharyngeal and vagus

Question 20

Describe the anatomical pathways of touch and pain.

Answer 20

Touch and pain differ in the level at which they cross over to the other side of the spinal cord.
Touch crosses over at the level of the caudal medulla
Pain crosses over immediately

Question 21

What is the clinical significance of this?

Answer 21

Brown-Sequard Syndrome

Question 22

What’s the difference between somatic and visceral pain?

Answer 22

Somatic pain is easy to localise
Visceral pain is difficult to localise
There are fewer visceral afferents than somatic afferents

Question 23

What scale is used to grade dyspnoea?

Answer 23

Modified Borg Scale

Question 24

What are the three types of dyspnoea?

Answer 24

Air Hunger
Tightness
Work/Effort of breathing