Flashcards in Physiology of Mouth, pharynx and oesophagus Deck (22)
What are the functions of saliva?
Lubricates food for swallowing
Helps with taste
Digestion (starch and lipids)
Protects oral cavity (destroy bacteria, alkaline environment)
How much saliva is produced each day?
800 - 1500ml each day
What is the pH range for saliva?
pH 6.2 - 8.0
Is saliva hypotonic or hypertonic?
If a solution has high osmolarity/osmolality, does it have high or low concentration?
What ions is saliva composed of?
High [K+], [HCO3-] and [Ca2+] (relative to plasma)
Low [Na+] and [Cl-] (relative to plasma)
thiocynate ions (antibacterial)
What enzymes is saliva composed of?
Digestive enzymes – salivary α-amylase, lingual lipase
Antibacterial agents – thiocynate ions, proteolytic enzymes (e.g. lysozyme), antibodies
What is the difference between serous and mucous saliva?
Serous - has enzymes
Mucous - no enzymes
Describe the structure of salivary glands.
Bunch of grapes appearance
Initial secretion by acini (lined by acinar cells). Ducts (lined by duct cells) modify this secretion. Myoepithelial cells contract to eject saliva
What modifications happen at the ducts for saliva production?
Absorption of Na and Cl from saliva
Secretion of K and HCO3 into saliva
Ductal cells impermeable to water, so saliva is hypotonic
What occurs in primary secretion of saliva production?
Isotonic ultrafiltrate from plasma diffuses through acinar cells.
Mixes with enzymes or mucins and drains into ducts
What type of saliva is highly modified (resting or stimulated)?
Resting - very hypotonic and neutral pH. Slaiva flow rate is lower and so more time for ductal modification
Which ion is selectively stimulated when saliva production is stimulated?
HCO3 - (increases with increasing flow rate)
What is xerostomia?
What are some causes of xerostomia?
dehydration, side effects, radiation therapy, Sjögren’s syndrome (autoimmune destruction of salivary and lacrimal glands)
What are the 5 taste classifications?
Sweet, sour, bitter, salty and umami
What kind of receptors are taste receptor cells?
What is the lower oesophageal sphincter? and its function?
Physiological sphincter at the gastro-oesophageal junction
Prevents reflux of gastric contents into the oesophagus
Higher resting basal tone
What 4 components form the 'physological sphincter' (Lower oesophageal sphincter)
Right crus of diaphragm
Acute angle of oesophagus entering stomach
Mucosal folds at the junction
+ve intra-abdominal pressure
What are the three phases of swallowing?
Oral, pharyngeal and oesophageal
What happens in the pharyngeal phase of swallowing?
Soft palate elevates – blocks of nasopharynx
Epiglottis tilts to cover opening of larynx