CASE 1 Flashcards
what is barrett’s oesophagus?
change of epithelium from stratified squamous to gastric glandular columnar epithelium in the lower part of the oesophagus
what layer of the oesophagus in barrett’s undergoes metaplasia, and then occasionally dysplasia?
mucosal layer
what is barrett’s a consequence of?
GORD - repeated damage from gastric reflux
barrett’s oesophagus is a major risk factor in what?
oesophageal adenocarcinoma
what is the sequence in barrett’s to cancer?
metaplasia-dysplasia-adenocarcinoma sequence
what are risk factors for barrett’s?
• GORD
• acid-bile reflux
• increasing age
• obesity
• white ethnicity
• male
• smoking (but not alcohol)
clinical features of barrett’s
the change from normal to premalignant cells is asymptomatic, however patients may have symptoms of acid reflux:
• heartburn
• regurgitation
• dysphagia
• haematemesis (vomiting blood)
• unintentional weight loss
• less common : chest pain, laryngitis, cough, dyspnoea,
wheezing
what is the main investigation in barrett’s?
upper GI endoscopy with biopsy
how does the oesophagus in barrett’s visually change?
paler squamous epithelium is replaced with ‘salmon-coloured’ columnar epithelium above the gastro-oesophageal junction (GOJ)
what is oral mucosa like?
thick stratified squamous epithelium which is resistant to abrasion, produces defensins to inhibit bacterial growth
what are the muscles of mastication and what are they innervated by?
innervated by CNV3 = masseter, temporalis, medial and lateral pterygoid
what does saliva contain?
water (99%), lipases and alpha-amylase, mucoproteins (lubricant), lysozyme, immunoglobulins (esp IgA), electrolytes, calcium and phosphate (dental repair)
superior vs inferior salivatory nucleus
• superior salivatory nucleus = CN VII = sublingual and
submandibular glands
• inferior salivatory nucleus = CN IX = parotid
where is Meissner’s plexus and what does it mainly control?
- submucosa
- controls mainly GI secretion and local blood flow
where is the myenteric plexus and what does it control?
- between longitudinal and circular muscle layers
- controls motility
- also secretes vasoactive intestinal polypeptide - the resulting inhibitory signals are especially useful for inhibiting some of the intestinal sphincter muscles that impede movement of food
what is the usual stimulus for peristalsis?
distention of the gut
peristalsis requires an active what?
myenteric plexus
what are the 4 swallowing stages?
- cephalic
- oral (voluntary)
- pharyngeal (involuntary)
- oesophageal (involuntary)
what is the cephalic stage?
thinking ab having a meal
The cephalic phase of digestion is the stage in which the stomach responds to the mere sight, smell, taste, or thought of food. About 20% of total acid secretion occurs before food enters the stomach.
what type of muscle is used in the oral and pharyngeal stages of swallowing?
striated
how does the neural control differ for the different 3 main stages of swallowing?
- oral = cortex/medulla
- pharyngeal = medulla
- oesophageal = medulla/ENS (mainly vagal nerve and ENS)
top part of oesophagus and pharynx controlled by __________ and bottom part by __________
top part of oesophagus and pharynx controlled by nucleus ambiguous and bottom part by dorsal motor nucleus of vagus
describe the chewing reflex
- the presence of bolus of food in the mouth initiates reflex inhibition of the muscles of mastication, which allows the lower jaw to drop
- the drop in turn initiates a stretch reflex of the jaw muscles that leads to rebound contraction
- this causes raising of the jaw to cause closure of the teeth, but it also compresses the bolus again against the linings of the mouth, which inhibits the jaw muscles once again, allowing the jaw to drop and rebound another time
- this leads to the physical breakdown of food, which is important for the digestion of many carbs
the rate of digestion is absolutely dependent on what?
the total SA exposed to the digestive secretions
upper oesophageal sphincter innervation?
CN X
for the UOS to open, what must relax?
cricopharyngeus
in swallowing, what happens after the tongue thrusts up and back?
- tongue thrusts up and back
- nasopharynx closed
- larynx elevated
- airway closed
- upper oesophageal sphincter open
- pharynx contracts
1 + 2 = bolus in mouth
3-6 = bolus moves through pharynx and UOS
what sphincter fails in GORD?
LOS
why is intraoesophageal pressure -ve?
lungs and pleura pull against oesophagus
taste nuclei?
nucleus solitarius : rostral (taste anterior 2/3 = CN VII), caudal (taste posterior 1/3 = CN IX)