The Mouth Flashcards
How does saliva protect the oral environment?
Keeps mucosa moist
Washes teeth
Maintains alkaline environment to neutralise acid produced by bacteria
High calcium concentration to prevent teeth from dissolving
Functions of saliva
Lubricates and wets food to help form a bolus
Begins digestion of carbohydrates with amylase
Prevents degradation of teeth with high calcium and being slightly alkaline
What are the names of the three paired salivary glands?
Parotid
Submaxillary
Sublingual
Type of secretion from the parotid gland? What proportion of total saliva?
Watery secretion rich in enzymes, little mucus
25%
Type of secretion of submaxillary gland? What proportion of total saliva?
Serous and mucous
70%
Type of secretion from sublingual? Proportion?
Viscous with no enzymes - lots of mucus
5% of total saliva
Structure of salivary glands?
Blind-ended tubes lined with acinar cells
Connected to a system of ducts lined with duct cells
Lead to a single outlet
Is saliva hyper or hypotonic?
Hypotonic
How is saliva produced?
Isotonic fluid (primary secretion) secreted by acinar cells which contains enzymes
Duct cells remove Na and Cl, add HCO3-
Duct cells are impermeable to water so it cannot follow resulting gradient
Under what conditions is saliva more hypotonic and why?
In low flow rates, most Na is removed because it is in contact with the duct cells for a longer time
Aldosterone also increases ductal recovery of Na
When does saliva become more alkaline? Why?
At high flow rates
Duct cells are stimulated to release more HCO3- so it becomes more alkaline
What controls saliva secretion?
Sympathetic - superior cervical ganglion
Parasympathetic - glossopharyngeal nerve and octic ganglion
How does the parasympathetic nervous system control saliva secretion?
From the otic ganglion.
Ach is released which acts in acinar cells
Stimulated to produce primary secretion
Duct cells stimulated ago add extra HCO3-
What drug can block the muscarinic receptors in the salivary glands?
Atropine
How does the sympathetic nervous system control saliva secretion?
Reduces blood flow to salivary glands, limiting salivary flow.
(Produces typical ‘dry mouth’ anxiety)
Where is autonomic outflow coordinated in regard to affecting saliva?
Centres in the medulla
What is saliva produced in response to?
Smell and taste of food
Conditioned reflexes
How much saliva is produced each day?
1.5L
Condition where there is no saliva production?
Zerostomia
What happens if there is reduced saliva production?
Difficult to eat food, needs to be moist or had with a drink
Teeth and mucosa degrade within weeks
What does saliva contain?
Na, Cl (lower concs than plasma)
Ca, K, I (higher concs than plasma)
HCO3, bacteriostats, mucus, enzymes
Main enzyme in saliva?
Amylase
Spinal levels of oesophagus?
From C6-T11
Three phases of swallowing?
Voluntary phase
Pharyngeal phase
Oesophageal phase
