Can be considered as two separate stages:
Pre-Ejection Phase
- Symptoms of nausea occur
- Sympathetic stimulation:
- Tachycardia, tachypnoea, sweating
- Parasympathetic stimulation:
- Salivation
- Upper and lower oesophageal sphincters relax
- Retrograde peristalsis to the stomach
Ejection Phase
- Protection of the airway occurs:
- Respiration temporarily ceases mid-inspiration
- Hyoid and larynx rise to open crico-oesophageal sphincter
- Glottis closes and soft palate elevates to close posterior nasal space
- Soft palate elevates to close off the nasopharynx
- Ejection of gastric contents follows:
- Contraction of the abdominal muscles results in raised intra-abdominal pressure
- Gastro-oesophageal sphincter opens