Swallowing/Gag Reflex Flashcards
What is swallowing initiated by?
When pressure receptors are stimulated by food or drink, forced into the rear of the mouth by the tongue
Where are pressure receptor for swallowing found?
Walls of the pharynx
What is the pharynx?
3 continuous segments shared between the GI and respiratory tracts
What nerve does the nasopharynx innervate?
Maxillary nerve (V2 (second branch of trigeminal nerve (V))
What nerve does the oropharynx innervate?
Glossopharyngeal nerve (IX)
What nerve does the laryngopharynx innervate?
Vagus nerve (X)
What are the 3 stages of swallowing?
- Voluntary (mouth)
- Involuntary (pharynx)
- Involuntary (oesophagus)
What happens in the voluntary (mouth) stage?
Food chewed & pushed to oropharyx
What happens in the involuntary (pharynx) phase?
Nasopharynx closed
Hyoid elevated
Epiglottis closed, stop food going down windpipe
Pharynx becomes shorter and wider (longitudinal muscles)
What happens in the involuntary (oesophagus) stage?
Pharynx sequential contraction (circular muscles) up to upper oesophageal sphincter
Peristaltic waves along oesophagus to lower o sphincter
Hyoid depressed
Epiglottis & nasopharynx open
How long does oesphaogeal peristaltic wave take to reach the stomach?
9 seconds
What anatomical feature that prevents oesophageal reflux of acid?
Lower oesophageal sphincter at cardiac notch
What is acid reflux caused by?
Pressure caused by pregnancy/big meds
What does continuous reflux into the oesophagus cause?
GORD - gastro oesophageal reflux disease
What can GORD cause?
Metaplasia - when epithelium changes from stratified squamous non-keratinising to simple columnar of GI
Can’t perform function properly
