oesophagus and its disorders Flashcards
brief phsyiology of oesophagus
fibromuscular 25cm tube of striated squamous epithelium
where is the oesophagus
posterior to the trachea
begins at end of laryngopharynx and joins stomach a few cm from diaphragm at the cardiac orifice
what does the oesophagus do
transports food to the stomach and secretes mucus
how is muscle type distributed in the oesophagus
skeletal muscles surround the upper third - smooth muscle in the lower 2/3
action of the upper oesophageal sphincter
striated muscle - constricts to stop air entering oesophagus
action of the lower oesophageal sphincter
smooth muscle - intra abdominal segment - acts as flap valve. it’s an area of high pressure, with intrinsic and extrinsic components
what can malfunction of the intrinsic and extrinsic components of the LOS do
lead to GORD
intrinsic components of the LOS
thick oesophageal smooth muscle
clasp-like semicircular smooth muscle fibres
myogenic activity - some resting tone, but less ACh-responsive
extrinsic components of the LOS
crural diaphragm encircles LOS - forms channels where oes. enters abdomen.
what makes up the extrinsic sphincter
fibres of the crural portion of the diaphragm which possess and pinchcock-like action - has myogenic tone
in neural control of oes. sphincters, what happens when ach is released
contraction of intrinsic sphincters
what cause relaxation of intrinsic sphincters
nitric oxide and vasoactive intestinal peptide release
how is the upper part of the oes innervated
supplied by somatic motor neurons of the vagus nerve, w/o interruption
how is the lower part of the oes innervated
visceral motor neruons of vagus nerve w/ interruptions - synapses w/ postganglionic neurons - cell bodies in oesophagus and splanchnic plexus
what encircles the lower oes.
nerves of the oesophageal plexus
functions of the oesophagus
swallowing - conveys food, fluid from the pharynx to the stomach
what triggers swallowing
afferent impulses in the trigeminal, glossopharyngeal and vagus nerves
what is swallowing coordinated with
opening and closing of the upper and lower oes. sphincters
how is swallowing initiated
- voluntary action - material on tongue collected, pushed back into pharynx
- waves of INvol contractions push the material into the oesophagus
what does #MOLO stand for
Mouth
Oropharynx
Laryngopharynx
Oesophagus
how does inhibition of respiration occur
nasopharynx closed off
closure of glottis by epiglottis
prevents food entering trachea
what is secondary peristalsis
peristalsis of oes. after stimulation of receptors on distension of the lumen by food.
what prevents reflux of the gastric contents
LOS closes after material has passed
abd pressure acts on oes.
pinchcock effect of diaphragm of LO
how do mucosal folds help prevent reflux of gastric contents
plug-like action of mucosal fold occludes the lumen of the gastro-oesophageal junction
what is achalasia
loss of coordinated peristalsis/spasm of LOS - food fails to reach the stomach
symptoms of achalasia
long period of sporadic dysphagia
food regurgitation
spasm disorders - chest pain, not of cardiac origin
achalasia aetiology
damage to innervation of oesophagus
degenerative lesions to vagus nerve and loss of ganglionic cells in the oesophagus
methods of diagnosis for achalasia
radiography - Ba swallow
oesophageal manometry
what is oesoohageal manometry
test if oes if relaxing and contracting properly - diagnoses swallowing problems
what are normal manometry results
normal LOS pressure
normal muscle contractions upon swallowing
what does low LOS pressure suggest
GORD, although this can occur in individual with normal LOS pressure
procedure for manomentry
local catheter: nostril > stomach deep inhale, swallow water measure strength and coord of muscle contractions, and LOS function slowly remove catheter
methods of achalasia treatment
endoscopic balloon dilatation of LOS/surgery to weaken sphincter
inhibtion of Ach release by injecting botox into LoS
what causes GORD symptoms
irritation caused by gastric contents
benefit of reflux stimulating salivation
saliva is an antacid - enhances, dilutes, neutralises refluxed gastric contents
what are the consequences in GORD of a low salivation rate
lack of ability to swallow own saliva - prolonged contact of refluxed material with oesophagus > oesophageal irritation/damage
cause of reflux in GORD patients
Transient spontaneous relaxation of LOS aka TSR
what causes TSR
resting LOS pressure too weak to resist pressure within the stomach - sudden relaxation of LOS, not induced by swallowing
what factors contribute to the severity of GORD
weak/uncoordinated oesophageal contractions - length of time in contact with gastric contents
amount of pressure placed on the anti reflux barrier
when does reflux occur
after eating, lying down, and when there is delayed gastric emptying - impaired gastric emptying alone can cause severe GORD
use of secondary peristalsis in GORD
causes salivation - neutralises acid in oesophagus
what causes GORD
reflux of gastric contents through the LOS - chronic oesophagitis
RFs through GORD
pregnancy, obesity
fat, chocolate, coffee, alcohol ingestion
large meals, esp if high acid content - onions, tomatoes
cigarettes
drugs
GORD complications
reflux causes desquamation of oesophageal cells - causing ulceration and basal cell hyperplasia
barrett’s oes. may form
clinical features of GORD
low/absent resting LOS tone
LOS tone fails to increase when lying flat
poor oesophageal peristalsis - dec acid clearance
delayed gastric emptying
GORD symptoms
heartburn, acid regurgitation
wake up at night due to laryngeal irritation by reflux
dysphagia
why does GORD occur in pregnancy
increased abdominal pressure from foetus - gastric contents forced into oesophagus
what causes heartburn in the absence of pregnancy
large meals - less efficient LOS
potential long term effects of GORD
oesophagitis, oesophageal strictures
squamous cell carcinoma
barrett’s syndrome
ulcer
if a patient has heartburn/nausea after eating (GORD) or problems swallowing / achalasia what will get ordered
MANOMETRY
how is GORD treated through lifestyle change
raise head of bed, dec intake of food that precipitates attacks, take antacids, lose weight
what surgery treats GORD
anti - reflux surgery: fundoplication - wrap fundus around LOS
what drugs can treat GORD
H2 receptor antagonists, Proton pump inhibitors
Metclopramide - may enhance peristalsis and aid acid clearance
how do antacids work
neutralise gastric acif - inc pH of gastric lumen
inhibit peptic activity
stop acid secretion
complication of using Mg salt antacid
can cause diarrhoea
complication of Aluminium salts as antacid
constipation
how does combination of alginic acid & saliva help protect from GORD
forms raft which floats on content of gastric lumen and protects oesophageal mucosa from reflux
what is essential to stop ulcers returning
removal of H. pylori
