sensory aspects of resp disease

Question 1

what is a symptom?

Answer 1

• an abnormal or worrying sensation that leads a person to seek medical attention

Question 2

what is the difference between sensory stimulation and sensory impression?

Answer 2

sensory stimulus –> transducer –> excitation of sensory nerve –> integration CNS –>sensory impression

( this is neurophysiology )

sensory impression –> perception –> evoked sensation
( this is behavioural psychology)

Question 3

what is the function of a cough?

Answer 3

• crucial defense mechanism
• protecting the lower resp tract
• inhaled foreign material
• excessive mucus production

Question 4

what does a cough come after?

Answer 4

• mucociliary clearance

Question 5

what happens in the expulsive phase of a cough?

Answer 5

• once the mucus gets to the large airways it stimulates he cough
• it generates a high-velocity airflow
• expels the mucus or foreign material
• this is facilitated by mucus secretion

Question 6

where are cough receptors normally found?

Answer 6

• they are most numerous on the posterior wall of the trachea
• they are found at the main carina
• they are less numerous in the more distal airways
• they are absent beyond the bronchioles
• normally found on the proximal airways

Question 7

what are the three types of sensory receptor in the lungs and the airways?

Answer 7

• slow adapting stretch receptors
• rapidly adapting stretch receptors
• C- fibre receptors

Question 8

what cranial nerve is the vagus nerve?

Answer 8

the 10th cranial nerve

through which all the sensory nerves from the airways pass through to the brain

Question 9

what is caspaicin?

Answer 9

• this is a stimulus to the sensory nerve

Question 10

what is the stimulus for C fibres?

Answer 10

• stimulated by chemicals

Question 11

what is the stimulus for the rapidly and slow adapting stretch receptors?

Answer 11

• inflation

- caspaicin has no effect

Question 12

what happens to the stretch receptors after an INCREASE in tracheal pressure?

Answer 12

• the rapidly adapting stretch receptors stop firing and he slows adapting stretch receptors are stimulated to fire

these receptors are involved in coughing

Question 13

what are features of C fibre receptors

Answer 13

• they have free nerve endings
• they are present in the upper airways
• they are small and unmyelinated fibres
• the conduction is slow
• releases neuropeptide, inflammatory mediators

Question 14

what are features of rapidly adapting stretch receptors?

Answer 14

• they are myelinated
• conduct very fast
• present in nasopharynx, larynx trachea and bronchi
• stimulated with hyperinflation causes a rapid response

Question 15

features of the slowly adapting stretch receptors?

Answer 15

• located in smooth muscle airway
• myelinated
• therefore also conduct very quickly
• mechanoreceptors
  they also respond to lung inflation

Question 16

what types of receptors lead to coughing?

Answer 16

• mechanoreceptors

- nociceptors

Question 17

what are the mechanoreceptors stimulated by?

Answer 17

• mechanical displacement

- citric acid

Question 18

what are nociceptors activated by?

Answer 18

• caspaicin
• bradykinin
• citric acid

Question 19

what is the complete cough pathway?

Answer 19

• sensory information goes via the vagus nerve and through the brainstem to the cough center
• this cough center consists of nucleus tractus solitarius
• the nucleus tractus solitarius is a collection of neurones that are connected to the medullary cough pattern generator
• from the medullary cough pattern generator, you can stimulation of various muscles to produce the cough
• the complete cough pathway also includes the cerebral cortex

Question 20

what are the afferent neural pathways for a cough?

Answer 20

• stimulation of the mechanical or chemical receptors leading to impulses going up the vagus nerve
• travels through the brainstem to the cough center
• some of the signals goes to the cerebral cortex

Question 21

what are the efferent neural pathways for a cough?

Answer 21

• involves the stimulation of various muscles

- which leads to the closure of the glottis and the production of the cough sound

Question 22

what are the 3 phases of a cough?

Answer 22

• inspiratory phase (opens trachea)
• glottic closure
• expiratory phase

Question 23

what happens to the intrapulmonary pressure during the act of coughing?

Answer 23

• increase in intrapulmonary pressure
• this compresses the posterior membrane of the trachea
• which pushes and narrows the trachea into a crescent shape
• this increases the flow and emphasizes the sound that is produced

Question 24

what is an acute cough?

what is it normally caused by?

Answer 24

lasts less than 3 weeks

- caused by a rhinovirus

Question 25

what is a chronic cough?

Answer 25

``` - lasts more than 3 weeks most common causes are : - asthma - gastroesophageal reflux (when protons coming up from stomach activate the cough receptors) - rhinosinusitis ```

Question 26

what happens to the mucus when there is an infection?

Answer 26

- the mucus may change color and become yellow

Question 27

what is an increased cough reflex?

Answer 27

- cough hypersensitivity syndrome - this is like a cough that is hard to control - triggers might be deep breath, laughing, talking ect. temp change, lying flat

Question 28

how to identify an increased cough reflex?

Answer 28

- giving the patient a range of doses of caspaicin - give diluted amounts and keep increasing the concentration - chronic coughers are particularly sensitive to this

Question 29

what is the mechanism of getting cough hypersensitivity?

Answer 29

- increased excitability of the afferent nerves by chemical mediators - results in an increase in the number of receptors - this also increases the neurotransmitter - there might also be an increase in inflammatory mediators

Question 30

what are current suppressants for coughing?

Answer 30

- using opiates | however they do come with side effects

Question 31

``` what are the sensory nerves coming from each of these places? nose pharynx larynx lungs chest wall ```

Answer 31

``` nose = trigeminal pharynx = glossopharyngeal + vagus larynx = vagus lungs = vagus chest wall = spinal nerves ```

Question 32

what is the difference between the anatomical pathways of touch and pain?

Answer 32

- the level at which the pathways cross over to the contralateral side - touch goes to the contralateral side at level of CAUDAL MEDULLLA - pain goes to the contralateral side at the level of the same anatomical level - direct

Question 33

what are the two types of pain?

Answer 33

- somatic pain | - visceral pain

Question 34

what is the nature of somatic pain?

Answer 34

very localised pain | - there are lots of somatic afferents

Question 35

what is the nature of visceral pain?

Answer 35

very generalized pain difficult to identify | the number of visceral afferents are fewer

Question 36

where might chest pain from respiratory disorders be coming from?

Answer 36

- pleuropulmonary disorder - tracheobronchitus - inflammation - referred pain

Question 37

where might the pain come from if not the resp system?

Answer 37

- cardiovascular disease - gastrointestinal - referred pain

Question 38

what is dyspnoea?

Answer 38

- shortness of breath | - occurs at low levels of exertion