9 Sensory Aspects of Respiratory Disease Flashcards
Q: Define symptom. 3 examples related to respiratory disease.
A: An abnormal or worrying sensation that leads the
person to seek medical attention
e.g. Cough
Chest pain
Shortness of breathQ: Define physical sign. 4 examples related to respiratory disease.
A: An observable feature on physical examination
e.g. Hyperinflation of chest wall
Dullness on percussion of chest wall
Increased respiratory rate
Reduced movement of chest wall
Q: What are the 2 parts leading to a conscious sensation? Pathway (5,3). Variation.
A: 1. sensory stimulus (e.g. pain from a cut in the skin) -> transducer (sensor) -> excitation of sensory nerve -> (afferent nerves lead to CNS) integration of CNS -> CNS creates a sensory impression = NEUROPHYSIOLOGY
- (sensory impression) -> perception (of information) -> (brain interprets the information coming from the sensory nerves and you get) evoked sensation = BEHAVIOURAL PSYCHOLOGY (eg removal of hand from hot plate)
People react differently to different sensations
Q: Why is a cough considered crucial? (2) Second to? but important when?
A: crucial defence mechanism protecting the lower respiratory tract from
i) inhaled foreign material
i) excessive mucous secretion
Usually secondary to mucociliary clearance- BUT important in lung disease when mucociliary function is impaired and mucous production is increased
Q: Name a phase of a cough and state what occurs. What facilitates this? (2)
A: Expulsive phase of cough
generates a high velocity of airflow facilitated by bronchoconstriction and mucous secretion
Q: Describe nerve profiles in airways. (3)
A: - lots of nerve terminals project out into airway from rich plexus of fibres
- well placed to sense the external environment (e.g. by mechanical stimulation of the nerve terminal by dust or right next to goblet cell)
- nerve terminal could respond by triggering a cough
Q: What are the 3 types of stretch receptors in the airways and lungs?
A: 1. C – fibre receptors (fibres particularly sensitive to chemicals)
- Rapidly adapting stretch receptors (to a stimulus)
- Slowly adapting stretch receptors
Q: What are C-fibre receptors? (2) Where are they found? (4) What do they react to? (2) What do they release? (3)
A: “free” nerve endings of small unmyelinated fibres (C)
Larynx, trachea, bronchi, lungs
- Chemical irritant stimuli
- inflammatory mediators
Release neuropeptide inflammatory mediator:
- Substance P
- Neurokinin A
- Calcitonin Gene Related peptide
Q: What are rapidly adapting stretch receptors? Where are they found? (4) What do they respond to? (3)
A: Small, myelinated nerve fibres (A delta)
- naso-pharynx
- larynx
- trachea
- bronchi
- Mechanical= mainly to inflammation (increased tracheal pressure)
- chemical irritant stimuli
- inflammatory mediators
Q: What are slowly adapting stretch receptors? Where are they found? (2) act as? What do they respond to?
A: Myelinated nerve fibres
Located in airways smooth muscle- Predominantly in trachea and main bronchi
Mechanoreceptors -> Respond to lung inflation/inflammation (increased tracheal pressure)
Q: Recording from airway vagal afferent nerves in an experiment using anaesthetised rats.
Why vagal afferent nerves?
What is given as a stimulus?
How do C-fibres respond to the stimulus?
How do rapidly acting and slow adapting stretch receptors react to the stimulus?
What is the next stimulus? why?
How do rapidly acting and slow adapting stretch receptors react to the stimulus?
The vagus is the 10th Cranial Nerve through which ALL sensory nerves from the airways pass through to the brain
Caspaicin has been given which is a stimulus to the sensory nerves
C: stimulated when the caspaicin is injected intravenously
no effect on them
tracheal pressure (MAIN STIMULUS for the rapidly and slow adapting stretch receptors is INFLATION)
rapidly adapting stretch receptors STOP firing + slow adapting stretch receptors are STIMULATED to fire
Q: What are the 2 main receptors to the cough reflex? What’s the difference? What do they each respond to? (2,4)
A: Mechanorsensors (only myelinated stretch receptors) and Nociceptors (stretch or C fibre)
M have cell bodies in nodose ganglion
N have cell bodies in jugular ganglion
MECHANOSENSORS are activated by:
- Mechanical Displacement
- CITRIC ACID
NOCICEPTORS are activated by:
- CASPAICIN
- Bradykinin
- Citric Acid
- Cinnamaldehyde
Q: Name 3 things that are present on nociceptors? Shape of mechanosensors?
A: TRPV1, TRPA1 and B2
bit like a tree
Q: Describe the afferent pathway for a cough. (5)
A: 1. Mechanical
(e.g. dust, mucous, food/drink)
Chemical
(e.g. noxious, intrinsic inflammatory agents)
- stimulation of irritant receptors (RARs)/cough receptor which are mechanical or chemical
- go via vagus nerve (or superior laryngeal nerve if from pharynx/larynx) up brainstem
- to ‘cough centre’ in medulla
- to cerebral cortex
Q: Describe the efferent pathway for a cough. (3)
A: 1. cerebral cortex of brain has analysed info coming in
- to ‘cough centre’ in medulla
- stimulation of various muscles leading to the and the production of sound
i) closure of the glottis
ii) expiratory muscles of abdomen
iii) diaphragm
Q: What are the 3 phases of a cough? Draw a graph. What’s brain activity like when you feel like you need to cough? Sound?
A: 1. Inspiratory Phase = opens up the trachea
- Glottic Closure (main sound starts at end of this)
- Expiratory Phase
REFER- subglottic pressure (below larynx) and flow rate lines
brain is really active when you feel the need to cough eg premotor cortex
