Sensory aspects of respiratory disease

Question 1

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

Answer 1

Sensory stimulus->transduced->excitation of nerve->CNS integration->impression
That is neurophysiology-the sensory impression from activation of a pathway
Sensory impression->perception->evoked sensation –the brain interprets the information-can be different in different people

Question 2

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

Answer 2

Most are found in posterior wall of trachea, carine, and less present in distail airways-completely absent in brocnhials, only proximal aiways
Common at branching points

Question 3

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

Answer 3

Slow adapting stretch receptors, rapidally adapting stretch receptors and C-fibre receptor

Question 4

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

Answer 4

For lung and airway (not trachea)-Vagus

Question 5

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

Answer 5

C-fibers depend on CHEMICALs to be activatied-in experiments often capsaicin. These have no effects on the stretch receptors

Question 6

6. What stimulates C-fibres?

Answer 6

Chemicals (eg capsaisin)

Question 7

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

Answer 7

Increases and decreases in INFLATION. Eg: tracheal pressure-rapidelt adapting stop firing, and slow adapting are stimulated (probs most common in cough)

Question 8

8. Describe the differences between the three types of sensory receptor.

Answer 8

C-fibers are non myelinated (so slow), oteher two ARE

C fiber respondchemicals, other two are mechanoreceptors. Both respond to irritants and inflame mediators

Question 9

9. What are the two broad types of sensory receptor in the airways that lead to cough?

Answer 9

Mechanoreceptors (fast and slow) (activated by mechanical displacement and Citric acid and Nociceptors (chemical C-fibres-activated by capsaicin, dradykinin, citric acid, cinnamaldheyde)

Question 10

10. Other than mechanical displacement, what else activates the mechanoreceptors?

Answer 10

Citric Acid

Question 11

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

Answer 11

Sensory info arrives to the Nucleus tractus solitatus, connected to medullary cough pattern generator-so brainstem reflex

Question 12

12. What is this collection of neurons connected to?

Answer 12

The medullary cough pattern generator –they then generate through spinal chord a cough

Question 13

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

Answer 13

Acts of sleep, sensitising, urges to coughs

Question 14

14. What are the three phases of cough?

Answer 14

Inspiration, glottic closure (rise of pressure) and expiratory phase

Question 15

15. Describe the afferent and efferent pathways of cough

Answer 15

Afferent-sense signal goes back up using vagus nerve (or laryngeal If in treahcea and stuff)-to nTR and cortex. Both to medulla cough centor, which send signals back down to intercostals, diaphragm, glottis and stuff

Question 16

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

Answer 16

<3weeks-often caused by rhinovirus

Question 17

16. What are the causes of chronic cough?

Answer 17

> 3 weeks- asthla, GORD, Rhinosinisitis, drugs

Question 18

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

Answer 18

Also known as cough hypersensitivity syndrome –the persons receptors are more sensitive because increase of afferent nerves, increase in receptors and neurotranmotter. Can be tested using caspaicin

Question 19

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

Answer 19

Antitussives can be central (opiates like codien, dryhydrocodein), or peripheral (moguistine)
Or disease specific(eosinophil associated-corticosteroids), GORD-proton pump inhib, H2 inhbit

Question 20

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

Answer 20

Most V and IX

Question 21

20. Describe the anatomical pathways of touch and pain.

Answer 21

Touch and pain differ as
Touch mostly used alpha and beta fibers(myelinated)-and CROSSES in the spine AT the caudal medulla
Pain-C fibers, crosses at the level of where it is (crosses as it enters)

Question 22

21. What is the clinical significance of this?

Answer 22

Brown-Sequard syndrome-if you have a spine hemisection, touch fine on one side but pain on the other

Question 23

22. What’s the difference between somatic and visceral pain?

Answer 23

Visceral is from organs-difficult to localise as less afferent neuron
Somatic is skin and subcutaneous-very localised

Question 24

23. What scale is used to grade dyspnoea?

Answer 24

Clinical dysnpnea scale, or rated on a modified BORG scale

Question 25

24. List some chest pains caused by resp disorders. And some that are not

Answer 25

Resp pain- pleuritic, tracheobronchitis, rib fracture, referred pain
Non resp-CVD-MI, pericarditis, aneurysm, GI-Oesophageal rupture, GORD, Pysch-panic disorder

Question 26

24. What are the three types of dyspnoea?

Answer 26

Hunger for air, tightness, work/effort