Eric, about swallowing, I agree, but note #6 below, perhaps the tachycardia reflex from occasional swallowing is not significant:
Reflex bradycardia occurring in response to diving, nasopharyngeal
stimulation and ocular pressure, and its modification by respiration
and swallowing.
Gandevia SC, McCloskey DI, Potter EK.
1. Digital pressure applied to the eyes evokes reflex bradycardia in
human subjects and anaesthetized dogs. The bradycardia is most
pronounced when breathing stops. 3. Oculo-cardiac reflex bradycardia
in the dog is reduced by central neural inspiratory activity and by
the excitation of pulmonary afferents by inflation of the lungs. In
human subjects it is reduced when inspiratory efforts are made against
a closed glottis. 4. Nasopharyngeal stimulation with water evokes
reflex bradycardia in the anaesthetized dog. This bradycardia is
reduced by central neural inspiratory activity and by the excitation
of pulmonary afferents by inflation of the lungs. 5. Bradycardia
occurs in normal human subjects during immersion of the face in water
('diving'). This bradycardia is reduced when inspiratory efforts are
made against a closed glottis. 6. SWALLOWING evokes transient
tachycardia in human subjects. During diving or the application of
ocular pressure, swallowing reduces the reflex bradycardia which these
evoke.
DDeden