Swallowing + Saliva Flashcards
Which receptors are stimulated by food or drink?
Pressure receptors in the walls of the pharynx
Name the pharyngeal constrictor muscles.
Superior constrictor
Middle constrictor
Inferior constrictor
Which nerve supplies the pharyngeal constrictor muscles?
Pharyngeal branch of vagus nerve
Which nerve supplies the nasopharynx?
Maxillary nerve (V2 of trigeminal nerve)
Which nerve supplies the oropharynx?
Glossopharyngeal nerve
Which nerve supplies the laryngopharynx?
Vagus nerve
How many stages are there to swallowing? Which ones are voluntary and involuntary?
Stage 1: Voluntary
Stage 2: Involuntary
Stage 3: Involuntary
Describe stage 1 of swallowing.
- Food is compresses against roof of mouth and pushed towards oropharynx by tongue
- Buccinator and supra hyoid muscles allow chewing of food
Describe stage 2 of swallowing.
- Nasopharynx is closed off by soft palate - helps to form bolus of food
- Swallowing centre inhibits respiration, raises larynx and closes the glottis - prevents food from entering trachea. Epiglottis covers glottis.
- Pharynx is shortened and widened by elevation of the hyoid bone
What type of muscle surrounds the upper 1/3 of the oesophagus?
Skeletal
What type of muscle surrounds the lower 2/3 of the oesophagus?
Smooth
Describe stage 3 of swallowing.
- Pharyngeal constrictor muscles contract to drive the bolus of food down the oesophagus
- Upper oesophageal sphincter relaxes to let in food. Once food has passed, sphincter closes, glottis opens and breathing resumes
- Peristaltic waves move food down the oesophagus into the stomach - each wave takes 9 seconds to move food to stomach
- Lower oesophageal sphincter remains open and relaxed throughout swallowing
What is the gag reflex?
The reflex elevation of the pharynx. Caused by irritation of oropharynx. Reflex arc between glossopharyngeal and vagus nerves.
Give 3 functions of saliva.
- Lubricant for mastication
- Maintains oral PH at 7.4
- Releases digestive enzymes (alpha amylase) for starch digestion
What is released in the serous secretion of saliva?
Alpha amylase