Session 4 - Salivation And Swallowing Flashcards
What is in the composition of saliva?
Mostly water Rich in potassium and bicarbonate Mucins - help with lubrication Amylase - secreted by salivary glands Lipase - secreted by lingual glands Immune proteins - e.g. IgA, lysozyme, lactoferrin
What glands are responsible for salivation?
Parotid (mainly serous secretion)
Submandibular (serous and mucus secretion)
Sublingual (serous and mucus secretion)
Buccal (only mucus secretion)
What are the functions of saliva?
Lubricate the mouth Lubricate food Oral hygiene Enzymes for digestion - amylase,lipase Solvent for carrying taste molecules to taste buds Defence against microorganisms- lysozyme
Explain the role of saliva in oral hygiene.
- The flow of saliva helps wash away pathogenic bacteria, as well as food particles that provide their metabolic support.
- Saliva contains proteolytic enzymes (e.g. lysozyme) that destroy bacteria.
- Saliva contains antibodies that can destroy bacteria.
Is saliva production stimulated by sympathetic or parasympathetic nervous signals?
Parasympathetic is the main driver of saliva production.
Sympathetic stimulates secretion of small amounts of saliva, but also causes vasoconstriction which then reduces saliva production.
What is xerostomia?
Xerostomia is the feeling of oral dryness , which is often associated with hypofunction of the salivary glands.
What problems can result from xerostomia?
Difficulty swallowing Difficulty speaking Dental cavities Mouth ulcers Reduced taste sensation Increased susceptibility to oral candidiasis
Which drugs may cause xerostomia as a side effect?
Antimuscarinic - they decrease saliva secretion
Which cranial nerve supplies the parotid gland?
Glossopharyngeal (CN IX)
What cranial nerve supplies the submandibular and sublingual glands?
Facial nerve (CN VII)
Mumps causes swelling of what gland? Why is swelling of this gland particularly painful?
Mumps causes swelling of the parotid gland. The parotid glands have a tough fibrous capsule surrounding them which doesn’t stretch. This causes pain due to the build up of pressure.
What is a sialogram?
A test used to diagnose blockage of a salivary gland or duct in your mouth. It involves injecting contrast through the parotid duct into the parotid gland and then using X-rays to look for any blockage.
What are the three stages of swallowing? Which of these stages are under voluntary control?
Oral preparatory phase - voluntary
Pharyngeal phase - involuntary
Oesophageal phase - involuntary
What happens in the oral preparatory phase of swallowing?
Bolus is pushed back towards the pharynx.
Once the bolus touches the pharyngeal wall, the pharyngeal phase begins.
What happens in the pharyngeal phase of swallowing?
The soft palate seals off the nasopharynx.
Pharyngeal constrictors push the bolus downwards.
The larynx elevates, closing the epiglottis.
The vocal cords adduct (protecting the airway) and breathing temporarily ceases.
The upper oesophageal sphincter opens.
What happens in the oesophageal phase of swallowing?
The upper oesophageal sphincter closes.
Peristaltic wave carries the bolus down into the oesophagus.
Swallowing closes the airway and inhibits breathing, except for in babies. Why is it that babies are able to feed and breathe at the same time?
In babies the epiglottis projects up into the nasopharynx. The epiglottis directs milk laterally down into the oesophagus away from the airway.
As babies grow, their neck elongates and the epiglottis is pulled down.
At what points does the oesophagus narrow?
1) Junction of the oesophagus with the pharynx
2) Where the oesophagus is crossed by the arch of the aorta
3) Where the oesophagus is compressed by the left main bronchus
4) At the oesophageal hiatus
What sphincter prevents gastro-oesophageal reflux?
Lower oesophageal sphincter
