The anatomy of salivation and swallowing Flashcards
What is saliva composed of?
- Mostly water
- Rich in K+ and bicarbonate (keeps pH slightly alkaline so we don’t dissolve our teeth)
- Mucins help with lubrication
- Amylase
- Lingual lipase
- Immune proteins e.g. IgA, lysozyme, lactoferrin
What are the functions of saliva?
- Lubricates mouth + contributes to phonation
- Mastication
- Maintenance of oral health
- Immunity
- Solvent for taste molecules
- Beginning process of digestion
- Way of transmitting
What is the clinical term for a dry mouth?
- Xerostomia
What are our 3 pairs of salivary glands called?
- Parotid
- Sublingual
- Submandibular
How is salivary secretion regulated?
- Primarily autonomic
- Parasympathetic increases production via facial nerve (VII) and glossopharyngeal nerve (IX)
- Sympathetic causes vasoconstriction of blood vessels feeding salivary glands
What is parotiditis?
- Mumps
- Very painful because parotid gland is enclosed in a tough sheath, so can’t swell
- Causes inflammation of testes and ovaries, leading to infertility
What is parotid sialography used to diagnose?
- Stones forming in parotid gland
- Pain and swelling on anticipation of food
- Or feeling gritty little stones inside the mouth
What are the different phases of swallowing?
- Oral preparatory phase
- Pharyngeal phase
- Oesophageal phase
Outline the oral preparatory phase of swallowing
- Lasts 7.4 seconds
- Voluntary
- Pushes bolus towards pharynx
- Once bolus touches pharyngeal wall, pharyngeal phase begins
Outline the pharyngeal phase of swallowing
- Lasts 0.2 seconds
- Involuntary
- Soft palate rises and seals of nasopharynx
- Pharyngeal constrictors push bolus downwards
- Larynx elevates, closing epiglottis, preventing food from entering airway
- Vocal cords adduct (protecting airway)
- Breathing temporarily ceases
- Upper oesophageal sphincter opens
Outline the oesophageal phase of swallowing
- Involuntary
- Closure of the upper oesophageal sphincter
- Peristaltic wave carries bolus downwards into oesophagus
What causes aspiration pneumonia?
- When food is aspirated (inhaled into the lungs)
- Lungs are sterile but food is not
- Causes pneumonia
How can babies continue breathing while they feed?
- They don’t close their vocal cords when they swallow
Outline the neural control of swallowing and the gag reflex
- Mechanoreceptors detect something touching the back of the throat
- Glossopharyngeal nerve
- Medulla
- Vagus nerve
- Pharyngeal constrictors
How can a stroke affect someone’s ability to swallow?
- Muscles involved in swallowing may have been affected
- Pt needs to be assessed by a speech and language therapist
- Nil by mouth until assessment
Describe the anatomical position of the oesophagus
- Sat relatively far back in the chest
- Travels behind trachea
- Crossed over by left main bronchus - this squashes the oesophagus
Describe the muscle composition of the oesophagus
- Skeletal muscle
- Changes to smooth muscle
At which parts of the oesophagus is food likely to get stuck?
- Junction of oesophagus with pharynx
- Where oesophagus is crossed by arch of aorta
- Where oesophagus is compressed by left main bronchus
- At oesophageal hiatus
What prevents the gastro-oesophageal reflux?
- Functional sphincter formed from smooth muscle of distal oesophagus
- Diaphragm squeezes oesophagus to prevent acid from moving up
- Intra-abdominal oesophagus gets compressed when intra-abdominal pressure rises
- Mucosal rosette at cardia
- Acute angle of entry of oesophagus
Why do we need to prevent gastro-oesophageal reflux?
- Reflux disease can pre-dispose to oesophageal cancer
