Mouth, pharynx and oesophagus Flashcards
What are the functions of saliva?
Lubricates food for swallowing
Aids taste
Begins digestion
Protects oral environment
What enzymes are in saliva that aid digestion?
Alpha amylase (digestion of starch) Linguinal lipase (digestion of lipids)
What is the composition of saliva?
Hypotonic
Lower osmolarity than plasma
Contains water, mucus, digestive enzymes, antibacterial agents, high concentrations of potassium, bicarbonate and calcium, low concentrations of sodium and chloride
What is the pH of saliva?
6.2-8.0 (dependent on whether it is stimulated or not)
How much saliva is produced per day?
800-1500ml
What are the salivary glands?
- Parotid (serous saliva)
- Sublingual (mucus saliva)
- Submandibular (mixed saliva)
[Nb. Also buccal glands and Von Ebner’s glands on tongue]
What do Von Ebner’s glands produce?
Lingual Lipase
What is the structure of salivary glands?
Appearance like bunch of grapes
Acini (lined by acinar cells) produce initial secretion
Duct cells modify secretions
Myoepithelial cells contract to eject saliva
What happens during saliva production?
Isotonic ultrafiltrate from blood plasma is diffused through acinar cells where it is mixed with enzymes - saliva then drains into ducts
What happens during ductal modification?
Overall net absorption of solute but not water (ductal cells impermeable to water) leaving a hypotonic solution
Why does the composition of saliva differ when stimulated compared to resting?
At rest, saliva flow rate is lower allowing more time for ductal modification
What is Xerostomia?
Dry mouth
What are the key signs and symptoms of Xerostomia?
Burning sensation in mouth Dry throat/ tongue/ lips Difficulty swallowing and speaking Altered taste Halitosis
What are potential causes of Xerostomia?
Medication side effects Dehydration Anxiety Sjogren's Syndrome Radiation therapy
What are the 5 taste classifications?
Sweet Sour Bitter Salty Umami
Where are taste buds found?
Tongue (papillae)
Palate
Larynx
Pharynx
What cells do taste buds contain?
Taste receptor cells
Supporting cells
Basal cells (replace cells sloughed off the tongue)
What type of receptors are taste receptor cells?
Chemoreceptors
What is mastication?
Chewing - breaking up food to increase surface area for enzyme action - creates bolus for swallowing