3b.) Salivation & Swallowing Flashcards
State some functions of saliva
- Hydrate food- so you can make it into a food bolus
- Keep teeth healthy- by preventing too much acidity
- Immune defence
- Taste- acts as solvent to digest flavour molecules
- Start of digestion- enzymes
- Transmit infections
- Speech- moistens mouth
What is xerostomia?
State some possible causes
State some possible symptoms
- Reduced flow of saliva in oral cavity
- Drug side effects (e.g. antidepressants), mouth breathing, post-salivary gland surgery, radiotherapy to head, dehydration, anxiety
- Ulcers, bad breath, infection, pain upon eating
State the 3 salivary glands and describe their anatomical positions
- Parotid: in parotid region
- Submandibular: in submandibular triangle
- Sublingual: sublingual fossa (shallow groove on medial surface of mandible. Lie on floor of oral cavity proper)
Where does the parotid gland open into oral cavity?
Flap of mucosa lateral to 2nd top molar
Is salivation under hormonal or neural control?
Why?
Primarily neural (autonomic); hormones would be too slow
Describe the effects of the parasympathetic and sympathetic autonomic nervous system on salivation
- Parasympathetic: main driver- increases production
- Sympathetic: also stimulates secretions of small amounts but also causes vasoconstricion
Suggest possible consequences of reduced parasympathetic innervation
Dry mouth as salivation is primarily under parasympathetic control
What is mumps?
State signs & symptoms
- Contagious viral infection which causes swelling of the parotid gland
- Headaches, joint pain, fever, swelling of testes and ovaries
State the nerve that innervates all glands above level of oral fissure
State the nerve that innervates all glands below level of oral fissure
Explain mumps causes pain in parotid gland
Parotid glands swell but they are surrounded by tight capsule which is resistant to stretch hence this causes pain. Parotid gland innervated by trigeminal nerve.
What is parotid sialography?
Injecting die into parotid duct to visualise parotid gland
State the 3 phases to swallowing
- Oral
- Pharyngeal
- Oesophageal
Describe the oral phase of swallowing
- Voluntary
- Pushes bolus towards pharynx
- ~7.4 seconds
Describe pharyngeal phase of swallowing, include:
- Voluntary/involuntary
- When starts
- Soft palate role
- Pharyngeal constrictors role
- Larynx role
- Vocal cords role
- Upper oesophageal sphincter role
- Involuntary (0.2seconds)
- Begins when bolus touches pharyngeal wall
- Soft palate seals off nasopharynx
- Pharyngeal constrictors push bolus downwards
- Larynx elevates epiglottis
- Vocal cords adduct and breathing temporarily ceases
- Opening of upper oesophageal sphincter
Describe the oesophageal phase of swallowing, include:
- Voluntary or involuntary
- Oesphageal sphincter
- How bolus moves down oesophagus
- Involuntary
- Closure of upper oesophageal sphincter
- Peristaltic wave carries bolus down rapidly down oesophagus
Describe the movement of the food bolus in each of the three stages of swallowing
- Oral: pushed back onto pharyngeal wall
- Pharyngeal: oral cavity to beginning of oesophagus
- Oesophageal: oesophagus to stomach
State which nerve is responsible for each of the following:
- Sensory component of swallow reflex
- Motor function to muscles involved in swallow reflex
- Sensory: glossopharyngeal nerve (CNIX)
- Motor: vagus nerve (CNX)
Describe the reflex arc of swallowing and gag reflex
- Mechanoreceptors in pharyngeal wall detect food bolus
- Send signal via glossopharyngeal nerve to medulla
- Vagus nerve then creates motor response…
- e.g. contraction of pharyngeal constrictors
State the 4 points at which the oesophagus narrows
Describe how the type of muscle, in all muscles involved in swallowing, changes as you move from mouth to oesophagus
Voluntary to involunatary reflected by type of muscle
Describe how anatomy helps to prevent oesophageal reflux
- Functional sphincter formed from smooth muscle at distal oesophagus
- Mucosal rosette at cardia of stomach
- Oesophagus enters stomach at acute angle/oblique entry (creates flap valve)
- Intrabdominal oesophagus compressed when intrabdominal pressure increases
- Diaphragm acts as sphincter
Given that the salivary glands are compound tubuoalveolar glands, describe the roles of the different cell types in salivay gland
- Acinar cells: produces intial saliva
- Ductal cells: modify initial saliva- makes saliva hypotonic in comparison to plasma whereas it was isotonic
- Myoepithelial cells: contract to move saliva from gland into mouth
Describe how the duct cells modify initial saliva produced by acinar cells
- Duct cell has 3 transporters on lumenal side
- Duct cell has 2 transports on basolateral side
- Reduction in Na+ and Cl- greater than gain in HCO3- and K+ so net effect is to create hypotonic solution
Describe how modification to initial saliva changes as flow rate changes
- Greatest modification to saliva happens when flow is slower- increase time for modification
- Faster flow rate- less modification- saliva more like plasma
- HOWEVER, at higher flow rates, bicarbonate secreted at higher flow rates- EXCEPTION!
