6. Salivation and Swallowing Flashcards
What is the composition of saliva?
99% water and 1% various salts and solids
What is the ionic composition of saliva and why?
Hypotonic, tonicity depends on flow rate, Saliva produced at rapid rate so not enough time to chnage ionic composition
What 2 chemical compounds are rich in saliva?
Potassium and bicarbonate
What enzymes are found in saliva and what produces them?
Amylase (from salivary glands) and lipase (from lingual glands)
What different immune proteins are present in the saliva?
IgA, Lysozyme, lactoferrin
What is the function of the lactoferrin in saliva?
Sequesters iron, preventing it from being used by bacteria to prevent infections
What is the function of mucins in saliva?
lubrication
What are the different functions of saliva?
- lubrication
- protection
- digestion
what does lubrication due to saliva help with?
swallowing
speach
how does saliva act as protection?
- buffers acid
- washes away debris stuck in teeth
- antibacterial - lysozymes and lactoferrin
What in saliva helps to keep teeth healthy?
pH buffering of bicarbonates and immunological proteins
What is xerostomia?
Reduced flow of saliva in the oral cavity producing a dry mouth
What could possibly cause xerostomia?
Drugs, radiation treatment, salivary gland diseases (e.g. mumps)/removal, mouth breathing, autoimmune, dementia, dehydration
What drugs can cause xerostomia?
Antidepressants
What are the 3 different salivary glands?
parotid, submandibular, sublingual
Where is the parotid gland located?
Anterior to ear and SCM, between the zygomatic arch and inferior border of mandible
Where are the subamndibular and sublingual glands located?
In the floor of the mouth
What muscle separates the submandibular gland into its superficial and deep parts?
Mylohyoid muscle
how much saliva does each gland secrete?
parotid = 25%, serous, + enzymes submandibular = 70%, mixed sublingual = 5%, mucous, - enzymes
what is the nerve supply to salivary secretion?
autonomic
What is the main neural control of the salivary glands?
Parasympathetic innervation (increases salivation)
What parasympathetic nerve innervates the parotid gland?
Glossopharyngeal nerve (CNIX)
What parasympathetic nerve innervates the submandibular and sublingual gland?
facial nerve
How does sympathetic innervation affect salivation?
Small sympathetic innervation causes small amounts of salivation, increases sympathetic innervation causes vasoconstriction and cessation of salivation
describe how Saliva is hypotonic
• Initial saliva is isotonic and secreted by acinus
• Moved out of acinus into ducts by myoepithelial cells contraction
• Ductal cells are relatively impermeable to water
o However removes Na+ and Cl (water cannot follow)
o Secrete K+ and HCO3- ions
More Na+ and Cl removed than K+ and HCO3- ions secreted
Saliva ends up hypotonic
describe effect of flow rate on saliva tonicty
• At low flow rates, increased contact time with ductal cells, most hypotonic
• At higher flow rates, less contact time with ductal cells, least modification
o Except for HCO3- ions which are selectively secreted at higher flow rates
what can xerostamia lead to?
infections
tooth decay
halitosis
What is mumps?
Viral infection of the salivary glands causing inflammation
Why does mumps cause a lot of pain?
Parotid gland is enclosed in a tough fibrous capsule. This limits swelling of the gland, producing pain
What nerve innervates the capsule of the parotid gland?
Trigeminal
What do parotid stones in the duct cause?
Cause swelling of the parotid gland
How might a parotid gland stone resolve itself?
Swelling of the parotid gland causes increase in pressure which may force the stone out of the duct into the mouth
what is sjogrens syndrome?
Autoimmune disease —> dry mouth, swollen/painful salivary glands.
What are SIALOLITHS? Hint : think of gallbladder
Salivary stones
–> calcified –> pain when salivating –> associated with eating
what is the most common location of sialoliths?
WHARTONS DUCT
What is the importance of WHARTONS DUCT?
It’s the duct connnecting glands to mouth esp the SUBMANDIBULAR gland.
Which palate protects the oropharynx and nasopharynx respectively?
Hard palate protects OROPHARYNX
Soft palate protects NASOPHARYNX
What are the 3 phases of swallowing?
Oral preparatory phase, Pharyngeal, Oesophageal
Which of the swallowing phases are voluntary?
Oral phase
What occurs the oral phase?
preparing bolus
Pushes bolus towards the oropharynx.
When does the pharyngeal phase begin?
Once bolus touches the pharyngeal wall
What occurs in the pharyngeal phase?
- Soft palate elevates and seals off nasopharynx
- Pharyngeal constrictors push bolus downwards
- Larynx elevates, closing epiglottis
- Vocal cords adduct (protecting airway) and breathing temporarily ceases
- Opening of the upper oesophageal sphincter by relaxing
What causes the larynx to elevate and what does this cause?
Elevates due to action of the suprahyoid muscles, which causes closing of the epiglottis.
What happens in the oesophageal phase?
- Closure of the upper oesophageal sphincter
* Peristaltic wave carries bolus downwards into oesophagus
Where does the epiglottis sit in a baby?
Epiglottis sits higher up, causes liquids to flow laterally around it and into the oesophagus while still allowing the larynx to remain open.
Which nerve has sensory fibres to the pharyngeal wall?
Glossopharyngeal nerve CNIX
Which nerve has motor fibres to the pharngeal constrictor muscles?
Vagus nerve
Describe the swallowing/gag reflex?
Mechanoreceptors in pharyngeal wall → glossopharyngeal nerve → medulla → vagus nerve → pharyngeal constrictors
Define dysphagia.
Difficulty swallowing
What are the 4 narrowings of the oesophagus?
- junction of oesophagus with pharynx
- where oesophagus is crossed by aortic arch
- where oesophagus is crossed by left main bronchus
- at the oesophageal hiatus (in diaphragm)
What are the two different types of dysphagia?
Liquid - problems coordinating swallowing
Solid - blockage problems
How would liquid dysphagia present?
ineffective swallowing - Dribbling
material entering resp tract - Coughing + Choking when attempt to swallow
If caused by neurological problems, what is more difficult to swallow?
• Usually harder to swallow fluids (than solids) as these are more difficult to coordinate and
move as a unit into the GI tract
• Can more easily get into respiratory tract than solids
If caused by physical obstruction to lumen, what is more difficult to swallow?
• Solids typically harder to swallow than fluids
Causes of coordination problems w swallowing?
cerebrovascular accident
Parkinson’s disease
multiple sclerosis
What causes blockages to swallowing/solid dysphagia?
- Fibrous rings
- Tumours
- Achalasia-failure of LOS to relax
Describe a suitable investigation for Dysphagia to solid foods
Barium swallow
OGD (oesophageal/gastro/duodenoscopy)
CXR to check for external compression of oesophagus
What are some red flag signs for oesophageal cancer?
+55 years old
Cancer-like weight loss
Progressive dysphagia
Why is dysphagia progressive in oesophageal cancer?
Tumour slowly grows bigger, blocking off more of the oesphagus so whereas small foods and liquids can get past, eventually they’ll be a complete blockage
