Flashcards in GI 3 - Salivation + Swallowing Deck (30):
What are the functions of saliva?
- Protects oral cavity (keeps mucosa wet and neutralises bacterial acid)
- Moistens and lubricates food
- Begins digestion (enzymes)
- Solvent for taste molecules
- Can be involved in the transfer of disease
- Allows structures to pass over each other smoothly, for phonation
Approx. how much saliva do we produce per day?
What percentage of total saliva production is produced by each gland?
~ 70% Submandibular gland
~ 25% Parotid gland
~ 5% Sublingual gland
Name the 3 salivary glands:
1) Submandibular gland
2) Sublingual gland
3) Parotid gland
Do the salivary glands secrete serous or mucous fluids?
Parotid = serous
Submandibular = seous + mucous
Sublingual = mucous
List the constituents of saliva:
- Lingual lipase
- Immune proteins (IgA, Lyzozyme, Lactoferrin)
Name the 2 cell types responsible for saliva production:
- Acinar cells
- Ductal cells
When saliva leaves the acinus into the duct of the gland, is it hypotonic, isotonic, or hypertonic to plasma?
When saliva leaves the duct of the salivary gland, is it hypotonic, isotonic or hypertonic to plasma? Why?
- Ductal cells remove Na+ and Cl- from saliva
- Tight junctions between ductal cells prevent movement of water
= Less ions = hypotonic
Saliva contains Kallikrein. How does this protease increase the blood flow to the salivary glands?
It produces bradykinin, which causes vasodilation allowing an increase in blood flow
How does saliva change at high flow rates (when stimulated by parasympathetic fibres)?
- Becomes more isotonic
- More alkaline
- Higher enzyme content
The parasympathetic fibres to the salivary glands hitch-hike on cranial nerves to reach their destination. Which cranial nerves are involved?
Submandibular + Sublingual = CN VII (Chorda Tympani)
Parotid = CN IX Glossopharyngeal
Are the salivary glands stimulated by parasympathetic or sympathetic fibres?
How can otitis media lead to a dry mouth?
- Otitis media may damage Chorda tympani nerve which runs through the middle ear.
- Chorda tympani contains the parasympathetic nerve fibres which stimulate the submandibular and sublingual salivary glands
What is xerostomia? What can it be caused by?
- Medications - antidepressants, antihistamines
- Chemo- + Radiotherapy
- Sjogrens autoimmune disease
What are the complications of xerostomia?
- Increased plaque and tooth decay
- Gum disease
- Mouth sores
- Fungal infections
- Inflamed tongue
- Difficulty eating
- Poor taste
- No seal for false teeth
What are some causes of parotiditis?
- Viral infection (mumps, AIDs)
- Bacterial infection (s.aureus)
Why is parotiditis painful?
Parotid gland is enclosed in tight sheath, so when inflamed it pushes against this sheath
Where are the 4 main narrowings of the oesophagus? Why is it important to know these?
1) Junction of pharynx and oseophagus
2) Where crossed by arch of aorta
3) Where compressed by left main bronchus
4) Oesophageal hiatus
- Help predict where foreign bodies have lodged
Name the 3 phases of swallowing:
Do the vocal cords abduct or adduct during swallowing?
Adduct, to protect the airways
How long is the oesophageal phase of swallowing?
~ 9 seconds
How do babies breathe and swallow at the same time?
- Larynx elevates, epiglottis enters nasopharynx like a 'boulder in a stream'
- Milk goes around epiglottis into oesophagus
- Babies breathe through their nose at same time
Which cranial nerves are involved in the gag reflex?
CN IX Glossopharyngeal = afferent
CN X Vagus = efferent
Name the afferent nerve of the gag reflex:
CN IX glossopharyngeal
Name the efferent nerve of the gag reflex:
CN X vagus
What is GORD?
Gastro-Oesophageal Reflux Disease
- Stomach contents regurgitate up oesophagus due to incompetent lower oesophageal sphincter
- Results in heartburn, cough, sore throat, dysphagia
What are the risk factors for GORD?
- Hiatus hernia
What are the common complications of GORD?
- Oesophageal stricture
- Oesophageal ulcer
- Barrett's oesophagus