2. Swallowing Flashcards
What are the functions of mastication?
Lubricates food
Mixes food with salivary amylase
Mechanically breaks up food
Which three glands are important for salivation?
Sublingual
Submandibular
Parotid
What type of fluid does the parotid gland secrete?
Serous, watery
Contains amylase
What type of fluid does the sublingual gland secrete?
Mucous
What type of fluid does the submandibular gland secrete?
Mixed serous and mucous
Contains mucins
How much saliva do we secrete per day?
1 litre
What is the composition of saliva?
Mucins (glycoproteins)
Alpha-amylase, lingual lipase
Immunoglobulins, lysozyme
Na+, K+, Ca++, Mg++, Cl-, HCO3-, PO4—
What are the functions of saliva?
- Facilitates swallowing and speech
- Solubilizes food for tasting
- Digestion of starch
- Oral hygiene
- Buffering
What are the symptoms of xerostomia?
Dental carries
Mouth infection
Difficulty with speech, taste, swallowing
How does the stimulation of parasympathetics affect secretion of saliva?
Increases secretion of amylase and mucus, blood flow, growth
Which cranial nerves are involved in the secretion of saliva?
7, 9
How does the stimulation of sympathetics affect secretion of saliva?
Increases secretion of amylase and mucus
Decreases blood flow
Why does stress cause xerostomia?
Stimulation of sympathetics cuts off blood supply due to vasoconstriction
Not enough water or oxygen
What is the more technical name for swallowing?
Deglutition
What are the 3 phases of swallowing?
Oral
Pharyngeal
Esophageal
What are the layers of the gut tube from inside out?
Mucosa (epithelium, lamina propia) Muscularis mucosae Submucosa Muscularis externa (circular and longitudal) Serosa
Explain the intrinsic control of the gut
- Contents of the tube present the gut with stimuli into chemo, osmo and mechanoreceptors near epithelium
- Info fed into Auerbach’s plexus
- Autonomic motor nerves control endocrine and exocrine glands (local reflex)
- Info gets carried back to the CNS
Which afferents relay to the swallowing centre that food is present in the oesophagus?
5,9,10
Where is the swallowing centre located?
Pons and medulla
Which efferent cranial nerves control the pharyngeal stage of swallowing?
5,7,9,10,12
Describe the mechanism of the pharyngeal phase
- Soft palate raises
- Larynx shuts off and raises
- Epiglottis swings back
- UES relaxes
- Superior pharyngeal constrictor causes a peristaltic wave
Why does the soft palate raise when we swallow?
Prevents food going into the nasopharynx
Why is breathing inhibited when we swallow?
Stops us getting air in the oesophagus or food in the trachea
Describe the mechanism of the esophageal phase
- UES contracts and a primary wave of peristalsis moves to the LES
- Secondary waves are triggered if any food remains: allows oesophagus to collapse when not eating
