Oesophagus and its disorders Flashcards
Describe the anatomy of oesophagus?
Fibromuscular tube of striated squamous epithelium
Lies posterior to trachea
Begins at end of laryngopharynx + joins stomach a few cm from diaphragm
Beneath structure called cricoid cartilage
What promotes transport of ingested food into stomach?
Highly coordinated muscular process; involves contraction + relaxation of oesophagus which transports food through GIT
Initiated by presence of food in pharynx + as food travels you have successive relaxation + contraction mediated vagus nerve. Sphincters innervates oesophagus
Relaxation of sphincters (UOS + LOS)
What is function of upper oesophageal sphincter?
it will relax to allow food to go through + it will close immediately as food passes to prevent air entering into oesophagus
What is function of lower oesophageal sphincter?
It will remain open for as long as swallowing is occurring + as soon food passes, it will close to prevent reflux of gastric contents from stomach into oesophagus as it will cause cells lining oesophagus to come off which is damaging
Describe the muscle structure of oesophagus?
Skeletal muscles surround the oesophagus below the pharynx (upper third)
Smooth muscles surround lower two thirds
What type of muscle is upper oesophageal sphincter?
Striated muscle
What type of muscle is lower oesophageal sphincter?
Smooth muscle
What are intrinsic components of LOS?
oesophageal muscles:
- thick circular smooth muscle layers + longitudinal muscles
- Clasp-like semi-circular smooth muscle fibres on right side
- Sling like oblique gastric (Angle of His) muscle fibres on left side
What are extrinsic components of LOS?
Diaphragm muscles:
- crural diaphragm encircles LOS + forms channel through oesophagus enters abdomen
- fibres of crural portion of diaphragm possess a pinchcock like action (extrinsic sphincter; diaphragmatic sphincter)
Malfunction of intrinsic + extrinsic component of LOS leads to what disease?
Gastric oesophageal reflux disease (GORD
Describe the innervation of oesophagus?
involvement of cholinergic ( i.e. via Ach) and non- cholinergic, NANC (e.g. both NO + VIP) innervation in control of tone of LOS
Neural control of oesophageal sphincter : ACh + substance P: contraction of intrinsic sphincters, NO + VIP: relax intrinsic sphincters
What innervates upper part of oesophagus?
Vagus nerve
Splanchnic nerves
What innervates lower part of oesophagus?
innervated by visceral motor neurons of vagus nerve with interruptions
Describe oesophageal motor innervation?
Upper part is striated -> much of that is contracted providing no swallowing is occurring. Ach is important in this
Lower part is smooth muscle-> we have contraction + relaxation occurring dependent on context. VIP, NO + Ach is involved
What is function of oesophagus?
Swallowing (deglutition)
conveys food+ fluids from pharynx to stomach
What is swallowing triggered by?
afferent impulses in trigeminal (5th cranial nerve), glossopharygneal (important in taste) + vagus nerves
How is swallowing initiated?
- Voluntary action - collect material on tongue +push it backwards into pharynx
- Waves of involuntary contractions push material into oesophagus
Describe the passage in which food moves in body?
Mouth -> oropharynx -> laryngopharynx -> oesophagus + stomach
What are reflex responses of swallowing?
Inhibition of respiration (breathing) - nasopharynx is closed off
Closure of glottis (around vocal cords by epiglottis -> prevents food entering trachea
Ring of peristaltic waves behind material move it towards stomach
Second wave of peristalsis moves any food remnants along -> called secondary peristalsis
Swallowing is coordinated …
coordinated opening + closing of UOS + LOS
What prevents reflux of gastric contents?
- LOS- closes after material has passed
- Pinchcock effect of diaphragmatic sphincter on lower oesophagus
- Plug like action of mucosal folds in cardia - occludes lumen of gastro-oesophageal junction
What are types of oesophageal disorders?
Achalasia Regurgitation Aphagia oesophageal spasm Diffuse oesophageal spasm
What is aetiology of achalasia?
- disorders of motility or peristalsis of oesophagus
- damage to innervation of oesophagus
- degenerative lesions to vagus nerve + loss of myenteric plexus ganglionic cells in oesophagus
What are symptoms of achalasia?
dysphgia -> difficult or painful swallowing
vomitting
Heartburn
What is diagnosis of achalasia?
evaluate any swallowing disorders: patient history examination
Patient’s self report may suggest type of disorder responsible for complaints which may trigger tests required to determine or verify specific cause of compliant
What are the reasons why oesophageal monometry?
To determine cause of non-cardiac chest pain
To evaluate cause of reflux (regurgitation) of stomach acid and other contents back up into oesophagus (GORD?)
To determine cause of difficulty with swallowing food (does UOS/LOS contract and relax properly?)
What is reflux?
is retro-grade movement of gastric content into oesophagus due to relaxation of LOS?
- in normal individuals, reflux is often brief, relatively infrequent
What are causes of reflux in those with GORD?
Transient spontaneuous LOS relaxation
Resting LOS pressure is too weak to resist pressure within stomach
Sudden relaxation of LOS that is not induced by swallowing
What are factors that contribute to severity of GORD?
Weak or uncoordinated oesophageal contractions
Length of time oesophagus is exposed to gastric acid
Amount of pressure placed on anti-reflux barrier
What is factors associated with GORD?
Pregnancy or obesity
Fat, chocolate, coffee or alcohol ingestion
large meals ,tomatoes, orange juice, onions
cigarette
Drugs
