Saliva And Swallowing Flashcards
What are 3 functions of saliva?
- Lubrication
- Protection
- Digestion
How does saliva act as lubricant?
Due to mucus content, makes swallowing easier as well as speech (prevents a dry mouth)
How does saliva protect us?
- Has a cooling effect (drinking hot coffee)
- Warning sign of vomiting
- Buffers acid
- Washes away debris stuck in teeth
- Bacteria fighting substances (Lysosomes, lactoferrin- reduces iron availability to bacteria)
How does saliva aid digestion?
- Contains amylase to break down carbs (salivary glands)
- Lingual lipase breaks down fats, works in stomach and proximal small intestine (lingual glands)
Name the 3 salivary glands
- Parotid (most serous)
- Submandibular
- Sublingual (most mucous)
What proportion of saliva is made by parotid gland?
Describe its secretions
25%
Serous saliva with lots of enzymes
Where are the Sublingual glands?
Describe their secretion
What proportion of salvia is made here
- Underneath tongue
- Mucus- like saliva with less enzymes than Parotid Gland
- 5%
Are the salivary glands endocrine or exocrine
Exocrine, as they open into mouth through ducts
Describe the structure of the salivary glands
- Group of Acinar cells, lining Acinus
- Acinus connected to Ductus system, lined with Ductal cells (relatively impermeability to water)
Describe the process by which Saliva is made?
- Initial saliva is made in Acinus and is Isotonic
- Moved into ductal system by Myoepithelial cells of Acinus
- Ductal cells remove Na+ and Cl- from solution, whilst secreting K+ and HCO3- into solution (Ductal Modififcation)
- Overall, saliva is a Hypotonic at the end of the process
How does flow rate of saliva through the ductal system affect the amount of ductal modification that takes place?
What is the exception?
- At rest/ low flow rates, more modification occurs so saliva is most hypotonic (more contact time)
- When eating/ at high flow rates, less modification occurs so saliva is least hypotonic
E: Most HCO3- is secreted into saliva when eating/ at high flow rates
Describe the nervous control of the salivary glands
- Mainly parasympathetic (increases production)
- Sympathetic secretes smaller amounts of less watery saliva (more mucus)
List the innervations of the salivary glands
- Parotid: Glossopharyngeal nerve
- Submandibular: Branches of facial nerve
- Sublingual: Branches of facial nerve
What is Xerostomia?
What are the causes?
- A condition where not enough saliva is made
- Anything that causes glands to stop working properly (Medications/ autoimmune/ dementia/ dehydration/ radiation)
Lack of saliva can lead to infections- bacterial or viral.
State 1 possible viral infection
Mumps
What is Sjogrens Syndrome?
What can you get if it infects the salivary glands?
An autoimmune condition affecting many organs
- Dry mouth
- Swollen/ painful salivary glands
What are Sialoliths?
In which Gland are they most common?
Name the duct that connects this gland to the mouth
- Calcified stones within salivary glands, or more likely within the ducts
- Submandibular gland
- Wharton’s duct
How does a Sialolith present?
- Swelling and pain when eating/ thinking about eating
Name the 3 phases of swallowing
- Oral
- Pharyngeal
- Oesophageal
Describe the Oral phase of Swallowing
- Voluntary, uses a lot of tongue movements
- Involves preparing Bolus and moving it to Oropharynx
- Oral phase ends when bolus touches pharyngeal wall
Describe the Pharyngeal phase of Swallowing
- Involuntary, takes place in less than a second
- Soft palate seals off Nasopharynx
- Pharyngeal constrictor muscles push bolus downwards
- Larynx elevates, closing epiglottis
- Vocal cords adduct and breathing temporarily stops
- Upper Oesophageal Sphincter opens
Describe the Oesophageal phase of Swallowing
- Involuntary
- Upper oesophageal sphincter closes
- Peristaltic wave caries bolus downwards into esophagus
What is Dysphagia?
Difficulty swallowing
What are 3 things that could happen if we have problems coordinating swallowing?
- Ineffective swallow-> Dribbling out of mouth
- Material entering respiratory tract-> Choking + Coughing
Compare Dysphagia caused by neurological problems and physical obstructions
Neurological causes;
- Fluids are harder to swallow, as more difficult to coordinate movement down oesophagus as a single unit
- Can enter respiratory tract more easily than solids
Physical obstructions;
- Solids are harder to swallow, as they can’t get past the obstruction
Suggest 3 causes of Neurological Problems leading to Dysphagia
- Stroke
- Parkinson’s
- MS
Suggest 3 causes of Physical Obstructions leading to Dysphagia
- Fibrous rings within oesophagus (possibly due to scarring such as from repeated reflux)
- Oesophageal cancer
- Achalasia (Rare, failure of Lower OS to relax)
Describe how Dysphagia presents in someone with Oesophageal cancer
Progressive Dysphagia, as tumour is growing (lumen gets more obstructed)
For example,
- Initial Dysphagia to large blouses
- Progression to small blouses
- Progression to fluids
What presentation of patient would warrant investigating the possibility of oesophageal cancer
- Dysphagia above the age of 55, especially with other cancerous signs or progressive Dysphagia
Describe the secretion of the Submandibular glands
What proportion of saliva is made here?
- Mixed saliva with both Serous and Mucous components
- 70%
