- Mediated through the brainstem
- Axon reflexes may occur through sensory nerves alone
AXON REFLEXES:
- Substance P , vasodilator , transmit this reflex
- Initiated by mechanical irritaion or via histamine from mast cells
- Substance P releases histamine from mast cells and thus amplifies the response
REFLEXES FROM NASAL STIMULI:
- Stimulus: chemical irritation, temperature changes, physical stimuli.
- Response depends from sneezing to cardiovascular and respiratory responses.
- Sneezing is associated with:
- facial movements
- lacrimation
- nasal secretions
- vascular engorgement
- change in respiratory rate
- closure of larynx
- variable CVS responses
NASOPULMONARY REFLEXES:
- Increase airflow through one side of nose is associated with increased ventilation of homolateral lung due to relaxation of bronchiole muscle on the same side.
REFLEXES ACTING ON THE NOSE:
- exercise, emotion and stress causes vasoconstriction
- hypoxia cases same effect
- hperventilation causes nasal congestion
CUTANEOUS STIMULATION:
- cooling of feet, arm and neck skin causes vasoconstriction of nose
- pressure to axilaa or lying on the dependent side will cause congestion
CENRAL CONTROL:
- stimulation of hypothalamus( emption, exercise, flight and fight) cause vasoconstriction
- vagal overactivity causes prolonged congestion and nasal obstruction
- migraine may result in nasal symptoms, usually congestion and clear rhinorrhoea
