Oesophageal Function Flashcards
What happens if accurate swallowing isn’t achieved?
Choking
Aspiration (wrong hole)
What are the 3 phases of swallowing? Their sensory components are?
1) Oral (voluntary/striated muscle)
2) Pharyngeal (involuntary/stirated muscle)
3) Oesophageal (involuntary/ striated and smooth)
Swallowing centre
region in brainstem that receives sensory input from receptors in back of mouth and upper pharynx.
Also innervates swallowing muscles via cranial nerves
What is swallowing controlled by? What does that mean for stroke sufferers?
Cortex and brainstem. People who have had strokes in these areas can develop swallowing disorders
What are the phases of Oral Phase?
Preparatory phase ( formation of bolus) Transfer Phase (bolus propelled into the pharynx)
Describe Preparation phase (oral phase)
Saliva= Lubrication and dissolving Mastication = breaks down solids into smaller size, shape and consistency suitable for transport. Teeth grind, and tongue and cheeks position this to happen.
Describe Transfer phase (oral phase)
tip of tongue comes into contact with the hard palate.
close off anterior oral cavity
Bolus pushed to back off mouth
The Pharyngeal Phase #2
lasts
What are the 3 passages required to be closed in the pharyngeal phase?
1) mouth
2) upper airway/nasopharynx
3) Lower airway (to protect trachea from aspiration)
what is the UOS
upper oesophageal sphincter.
Acts as a barrier between the pharynx and oesophagus and is usually closed.
A complex of muscles often in a state of tonic contraction, that relaxes intermittently
What does UOS prevent?
air distending the stomach
reflux of contents into pharynx and larynx during oesophageal peristalsis
What muscles do UOS consist of?
Cricopharyngeus
Inferior Pharyngeal constrictor
cervical oesophagus
How is it that UOS opens how for how long?
- Cricopharyngeus relaxes
- suprahyoid and thyrohoid muscles contract
- pressure of descending bolus distendeds UOS
Opens for 0.5 s
Oesophagus Function and structure?
from UOS to LOS ~20-25cm long mucosa= stratified squamous epithelium upper 1/3 striated (voluntary) lower 2/3 smooth (involuntary)
Oesophageal Phase?
UOS relaxes, bolus enters and is propelled down oesophagus via peristalsis
Primary: initiated by swallowing, cont of pharyngeal contraction wave but slower, 3-5cm/s
Secondary: initiated by distention, activated stretch receptors initiate local reflex response > peristalsis
lasts 5-6s
How does oesophageal peristalsis occur
ANS (para/sympathetic) and the Enteric NS
What are the nerve plexus of the GI tract
submucosal plexus myenteric plexus (between circular longitudinal muscles)
Why is ES interesting?can operate independent/autonomously
can operate independent/ autonomously. Can also communicate with PS and S
The oesophagus is mostly covered in…
Adventitia
the circular layer contracts…
above and relaxes below bolus
the longitudinal layer
shortens during peristalsis
what is the LOS
a specialised segment of smooth muscle that is tonically contracted, close to the squamocolumnar junction (20-35 mmHg)
What causes LOS to relax
Swallowing: 1-2s after swallow, lasts 5-10s, followed by hypercontraction
Physiologically: intermittently relaxes to release air from stomach, only happens in an upright position, mediated via vagus nerve
Investigation of the Oesophagus
Gastroscopy: flexible telescope
Barium Swallow: xray test, asses function/motility
pH Study: may have reflux but unsure. involves cathater above gastro-oesophageal junction to test pH
Manometry: Like pH to test pressure/propagation of wave.
Structural diseases of the oesophagus
- inflammation
- ischemia/necrosis
- ulceration
- bleeding
- narrowing
- masses
- diverticulum
Dysmotility diseases of the oesophagus
abnormal contraction of the oesophageal muscles
Functional diseases of the oesophagus
disorders of motility, sensation and brain-gut dysfunction.
Gastro-oesophageal reflux disease
gastric contents into oesophagus. Occurs during transient LOS relaxation without the protective columnar epithelium, acidic contents damage.
When does Transient LOS relaxation become pathological?
When too much gastric juice refluxes into the oesophagus causing symptoms/disease
Causes of G-O reflux
Hypotensive LOS (caffiene, alcohol, fats or certain meds eg) beta-blockers, nitrates)
Hiatus Hernia
Impaired oesophageal peristalsis (less clearance)
Hiatus Hernia
Hiatus = diaphragm opening
diaphragm = additional support to the sphincter
stomach passes through hiatus into the chest, due to a diaphragmatic weakening, now you have an area that can freely reflux
pH of oesphagus and stomach
oesophagus= 6-7 stomach= 1-2
Symptoms of acid reflux
Heartburn
regurgitation
sour/bitter taste in mouth (worse after eating/lying down)
Why to the symptoms of gastric acids occur?
The gastric acid (pH 1-2) comes into contact with the oesophageal mucosa (pH6-7) which is sensitive to it, and nerve fibres give the sensation of burning. Chronic acid causes damage
Structural complication of GORD
Reflux oesophagitis (inflammation, ulceration and bleeding)
Peptic Stricture (narrowing from prolonged inflammation leading to fibrosis and scarring)
Barretts oesophagus
cancer
Whats Barrett’s oesophagus
Oesophageal epithelium (squamous) transforms to become like gastric (columnar + goblet) in an attempt to adapt to damage. "intestinal metaplasia" loss of z line
Evolution of Barrets oesophagus to cancer?
Squamous oesophagus > chronic inflammation > Barrets metaplasia > Low-grade dysplasia > High-grade dysplasia > cancer (adenocarcinoma)
2 types of oesophageal cancer the the risk factors
Adenocarcinoma (adenoCa): GORD, Barret’s
more in distal oesp/GO junction
Squamous cell carcinoma (SqCC): smoking, alcohol, diet
SqCC usually higher up
Ring/web
found distally, thin mucosal memmbrane, associated with hiatus hernia. Can obstruct passage of food, difficulty swallowing (dysphasia)
Zenker’s Diverticulum
Excessive pressure cause weakest part of pharynx to balloon out
Leads to poor swallowing and impair relaxation of cricopharyngeus, more common in eldery
Stricture
Peptic: reflux related
Caustic: custic injury
post-radiotherapy/surgical
malignant
Narrowing of oesophagus
Reflux oesophagitis
inflammation due to GORD. Bleeding, ulceration, perforation
1) bleeding - haematemesis (vomiting blood)
2) Dysphagia
can lead to peptic strictures
Oesophageal Candidiasis
Thrush, with white plaques coating oesophagus
Ulceration
Herpes simple virus. Pill induced (doxycycline)
or bisphosphates
Eosinophilic oesophagitis
Eosinophils infiltrate the epithelium of oesophagus = circular appearance
-allergy mediated
Motility Disorders of the oesophagus
Dysphasia present (difficult swallowing). Likely intermittent/variable symptoms. Liquids just as affected
Achlasia (motility disorder)
neuro-degenration of oesophageal nerves
- myenteric plexus and LOS inhibitory nerves
- loss of peristalsis and failure of LOS to relax, birds beak of dilation occurs
Diffuse oesophageal spasm
“corkscrew oesophagus”
non-peristaltic onset of contraction
-dysphasia and chest pain
Nutcracker Oesophagus
Normal but extremely strong peristaltic contractions
Sclerodema
CT disease, hardening (fibrosis) of skin and CT
Damage occurs to submucosa (nerves/BV) =rubbery hose-pipe
No peristalsis, weak contraction, LOS has no tone
-dysphagia and reflux
What can you use to diagnose motility disorders
manometry
Four landmarks that indent the oesophagus
cricoid
Aortic arch
left main bronchus
diaphragm
Sup border of mouth
hard & soft palate
Ant/Lat border of the mouth
Cheeks, lips, tongue body
Inferior border of the mouth
glenohyoid and thyrahyoid
Posterior border of the mouth
ulva (soft palate)
Palantine tounsils
root of tongue
Linguinal tonsil
