The Oesophagus and its Disorders

Question 1

What does the oesophagus do?

Answer 1

Transports food to stomach (eating gullet)
Secretes mucus
What promotes the transport of ingested food into the stomach?
This is highly coordinated muscular process; involves contraction and relaxation of the oesophagus which transports the food through the GIT
Relaxation of the sphincters (UOS and LOS)

Question 2

What is the oesophagus?

Answer 2

Fibromuscular tube (25cm) of striated squamous epithelium
Lies posterior to the trachea
Begins at end of laryngopharynx and joins stomach a few cm from diaphragm (at the cardiac orifice of the stomach)

Question 3

How is the oesophagus structured?

Answer 3

Skeletal muscles surround the oesophagus below the pharynx (the upper third)
Smooth muscles surround the lower two thirds
Oesophagus has 2 sphincters
Upper oesophageal sphincter (UOS); striated muscle;
Musculo-cartilaginous structure
Constricted to avoid air entering the oesophagus
Lower oesophageal sphincter (LOS); smooth muscle; acts as a flap valve
LOS- area of high pressure zone
LOS has intrinsic and extrinsic components
Intrinsic component- oesophageal muscles- under neurohormonal influence
Extrinsic component- diaphragm muscle (adjunctive external sphincter)
Malfunction of intrinsic and extrinsic components of LOS -> GORD

Question 4

What are the intrinsic components of the lower oesophageal sphincter (LOS)?

Answer 4

LOS has intrinsic and extrinsic components
Intrinsic components of LOS:
1. Thick circular smooth muscle layers and longitudinal muscles
2. Clasp-like semi-circular smooth muscle fibres on the right side:
Myogenic activity (some resting tone initiated by cells within), but less Ach-responsive
3. Sling-like oblique gastric (angle of His) muscle fibres on the left side
Work in concert with the clasp like-semi-circular smooth muscle fibres, help to prevent regurgitation- responsive to cholinergic innervation
Angle of His is poorly developed in infants as it makes a vertical junction with stomach, hence why reflux is common in infants

Question 5

What are the extrinsic components of the LOS?

Answer 5

Extrinsic components of LOS:
Crural diaphragm encircles the LOS
Forms channel through which oesophagus enters the abdomen
Fibres of the crural portion of the diaphragm posses a “pinchcock-like” action (extrinsic sphincter; diaphragmatic sphincter)- myogenic tone

Question 6

How is the oesophagus innervated?

Answer 6

Involvement of cholinergic (i.e. via Ach) and non-cholinergic, NANC innervation in the control of tone of the lower oesophageal sphincter
Neural control of the oesophageal sphincters:
Acetylcholine, SP- contraction of intrinsic sphincters
NO and VIP- relax the intrinsic sphincters
Extrinsic sphincters work in concert to push the food into the stomach

Question 7

How does innervation of the oesophagus differ with each part?

Answer 7

Upper part- striated muscle- supplied by somatic motor neurons of vagus nerve without interruption:
Vagus nerve
Splanchnic nerves (thoracic sympathetic trunks)- nerves that innervate internal organs
Lower part- smooth muscles-
Innervated by visceral motor neurons of vagus nerve with interruptions (synapse with postganglionic neurons; cell bodies in oesophagus and splanchnic plexus)
Oesophagus is also encircled by nerves of the oesophageal plexus
DVN- dorso vagal nucleus
NA- nucleus ambiguus
NTS- nucleus tractus solitarius

Question 8

How are innervation signals integrated during the swallowing reflex?*

Answer 8

do not know booboo

Question 9

What are the functions of the esophagus?

Answer 9

Swallowing (deglutition)
Conveys food and fluids from pharynx to stomach
Swallowing is triggered by afferent impulses in the trigeminal glossopharyngeal and vagus nerves
Efferent impulses pass tot eh pharyngeal musculature and the tongue
Trigeminal, facial and hypoglossal nerves (tongue muscles)
Integration of impulses in the nucleus of tractus solitarius (NTS), nucleus ambiguus (NA) and dorsal vagal nucleus
Recap- swallowing is coordinated opening and closing of the upper and lower oesophageal sphincters

Question 10

How is swallowing initiated and what happens after that?

Answer 10

1. Voluntary action- collect material on tongue and push it backwards into pharynx (skeletal muscle, mucus membrane)
   
   2. Waves of involuntary contractions push the material into oesophagus
      Food moves from Mouth -> Oropharynx -> Laryngopharynx -> Oesophagus and stomach
      Reflex responses
      Inhibition of respiration (breathing); nasopharynx is closed off
      Closure of glottis (around the vocal cords) by epiglottis; prevents food from entering the trachea
      Ring of peristaltic waves (4cm/sec) behind the material moves it towards the stomach
      A second wave of peristalsis moves any food remnants along

Question 11

How do muscles carry out swallowing?

Answer 11

Progressive muscular contractions and relaxations move the move the food towards the stomach and along the GIT
Swallowing difficulty (oropharyngeal dysphagia) is caused by the inability of the UOS to open or discoordination of the timing between the opening of the UOS and the pharyngeal push behind the ingested bolus

Question 12

What is secondary peristalsis?

Answer 12

Upon the relaxation of upper oesophageal sphincter (UOS), food passes
UOS closes as soon as food passes
Glottis opens
Breathing resumes
Lower oesophageal sphincter opens and stays open throughout swallowing
LOS closes after material has passed
A large food material does not reach the stomach after the first peristaltic wave
Stimulation of receptors upon distension of the lumen of the oesophagus by the food -> repeated waves of peristalsis (secondary peristalsis)
Is secondary peristalsis of any benefit?
Ensures that ingested food reaches the stomach

Question 13

What prevents the reflux of gastric contents?

Answer 13

1. LOS- closes after material has passed
   
   2. “Pinchcock” effect of the diaphragmatic sphincter on the lower oesophagus (side-to-side compression between “2 pillars” of the crus)
   3. Plug-like action of the mucosal folds in the cardia- occludes the lumen of the gastro-oesophageal junction:
      Abdominal pressure acting on the intra-abdominal parts of the oesophagus
      Valve-like effect of oblique entry of oesophagus into stomach- in adults only
      Sphincter muscles of UOS and LOS are strong circular muscles; act as valves to control the movement of food mass aborally (forward direction); prevent reflux by forming an opening when relaxed and closing completely when contracted
      Overall, there is an anti-reflex barrier in the region of gastro-oesophageal junction

Question 14

What are the types of oesophageal disorders?

Answer 14

Disorders of motility or peristalsis of oesophagus (assess the motor function of the UOS, LOS and oesophageal body) ( this is called achalasia)
Assess cause of regurgitation (e.g. reflux of stomach acids into oesophagus); weak LOS (called GORD)
Aphagia (determine cause of swallowing difficulty)
Abnormal oesophageal contractions and food is not effectively reaching the stomach (oesophageal spasm)
Diffuse oesophageal spasm- chest pain coming from the oesophagus (-angina)

Question 15

What is the pathophysiology of achalasia?

Answer 15

1/100,000; presents at any age
Findings may vary:
Impaired LOS relaxation (spasms)
Can be accompanied by impaired peristalsis (sphincter spasms)
Food and liquids fail to reach the stomach- delayed opening of LOS
Results in dilation of oesophageal body with distal narrowing (bird’s beak appearance) of the barium-filled oesophagus on esophagram
Long period of sporadic dysphagia (difficulty swallowing)
Regurgitation of food

Question 16

What is the aetiology of achalasia?

Answer 16

1. Disorders of motility or peristalsis of oesophagus (assess the motor function of the UOS, LOS and oesophageal body)
   
   2. Damage to the innervation of oesophagus
   3. Degenerative lesions to the vagus nerve and loss of myenteric plexus ganglionic cells in the oesophagus
      Initiating factor unknown, but thought to be autoimmune or triggered by infection

Question 17

Symptoms of achalasia?

Answer 17

1. Dysphagia- difficult or painful swallowing
   
   2. Vomiting
   3. Heart burn:
      Retrosternal burning sensation due to oesophageal dysmotility
      Retention of ingested (acidic) food
      Generation of lactic acid in the process of decomposition of retained food
      Also heart burn could be caused by the retention of small quantities of acid refluxed in the oesophagus due to poor emptying and incomplete relaxation of LOS

Question 18

How does one diagnose achalasia?

Answer 18

Evaluate any swallowing disorders; patient history examinations
The patient’s self-report may suggest the type of disorder responsible for the complaint which may trigger test required to determine, or verify the specific cause of the complain
The elderly- some abnormalities of swallowing may be frequent in the elderly
1. Barium radiography (barium swallow)- dilatation of oesophagus with beak deformity at lower end
Evaluates the entire swallowing channel (mouth, pharynx and oesophagus)
2. Oesophageal manometry- absent peristalsis

Question 19

What is oesophageal manometry performed and normal results?

Answer 19

Oesophageal manometry is performed for the following reasons:
1. To determine the cause of non-cardiac chest pain
2. To evaluate the cause of reflux (regurgitation) of stomach acid and other contents back up into the oesophagus (GORD?)
3. To determine the cause of difficulty with swallowing food (does UOS/LOS contract and relax properly?)
Allows evaluation of strength of coordination of muscle contractions
Relaxation function of LOS
Over the test evaluate if the oesophagus is contracting and relaxing properly
Normal results:
Normal LOS pressure and normal muscle contractions upon swallowing
Low LOS pressure suggests GORD, but GORD can occur in individuals with normal LOS pressure
What does high LOS pressure suggest?
Pressure of LOS <26 mm Hg is normal; >100mm Hg is considered achalasia; > 100mm Hg is nut cracker achalasia

Question 20

What do the results of oesophageal manometry mean?

Answer 20

Normal results of oesophageal manometry would show:
The pressure of the muscle contractions that move food down the oesophagus is normal
The muscle contractions follow a normal pattern down the oesophagus
Normal pressure of the LOS is about 15mmHg but:
-When the LOS relaxes to let food pass into the stomach, the pressure is less than 10mmHg
-If in the absence of letting food through, the LOS pressure is less than 10mmHg, GORD I suspected- do not confuse these 2
Abnormal results show/are characterised by:
Presence of muscle spasms in the oesophageal body
Presence of weak contractions along the length of the oesophagus
Achalasia is characterised by high LOS pressure which fails to relax after swallowing
Lack of a coordinated LOS relaxation in response to swallowing

Question 21

How does reflux work in normal people?

Answer 21

Is the retro-grade movement of gastric content into oesophagus, due to relaxation of the LOS
Reflux is often brief, relatively infrequent
Often occurs after meals in normal individuals (transient spontaneous LOS relaxation, tsr)
Reflux usually stimulates salvation
Saliva is an effective natural antacid- dilutes and neutralises refluxed gastric contents
Low rate of salivation; lack of ability to swallow own saliva -> prolongation of contact of refluxed material with oesophagus -> ??
Gastro-oesophageal reflux disease due to oesophageal irritation and oesophageal damage

Question 22

What is gastro-oesophageal reflux disease (GORD)?

Answer 22

Is the retro-grade movement of gastric content into oesophagus due to relaxation of the LOS?
Causes a burning sensation in chest after meals- angina-like pain?
GORD is when reflux is more frequent and troublesome
Low rate of salivation; lack of ability to swallow own saliva-> prolongation of contact of refluxed material with oesophagus-> oesophageal irritation and oesophageal damage

Question 23

Causes of reflux in those with GORD?

Answer 23

Causes of reflux in those with GORD:
1. Transient spontaneous LOS relaxation (tsr)
Some 98% of reflux events in normal individuals is associated with transient spontaneous relaxation (tsr) of LOS
But tsr accounts for only about 60% of reflux events in patients with reflux, so what accounts for the rest?
Other answers:
2. Resting LOS pressure is too weak to resist the pressure within the stomach
3. Sudden relaxation of the LOS that is not induced by swallowing
Recap- malfunction of extrinsic and intrinsic components of LOS-> GORD

Question 24

What are the factors that contribute to the severity of GORD?

Answer 24

1. Weak or uncoordinated oesophageal contractions (oesophageal irritation from reflux disease itself?)
   Prolonged duration of contact of refluxed digestive contents with oesophagus
   
   2. Length of time the oesophagus is exposed to gastric acid
      ↑ gastric acid secretion coupled with presence of bile in gastric contents -> severe oesophageal damage
   3. Amount of pressure placed on the anti-reflux barrier
      Reflux occurs after eating, lying down (supine) and when there is delayed gastric emptying
      Impaired gastric emptying alone can cause severe GORD

Question 25

What are the clinical features of GORD?

Answer 25

Resting LOS tone is low and absent
LOS tone fails to increase when lying flat or during pregnancy
Poor oesophageal peristalsis →↓clearance of acid
A hiatus hernia (impairs the functioning of LOS and diaphragm closing mechanisms)
Delayed gastric emptying
Symptoms:
Heartburn and acid regurgitation
Wake up at night- reflux irritates the larynx
Dysphagia

Question 26

How do you investigate GORD?

Answer 26

Low dose proton pump inhibitor (PPI) challenge is 1st line
Upper GI endoscopy
Manometry
24-hr ambulatory pH monitoring
Findings from continuous pH monitoring:
24 hr hour pH monitoring shows that most normal
individuals (non-refluxers) reflux on a daily basis
Therefore, GORD implies not just the presence of
reflux, but reflux in excess of that experienced by
non-refluxers

Question 27

How does pregnancy affect GORD?

Answer 27

Foetus increases pressure on abdominal contents
Pushes terminal segments of oesophagus into thoracic cavity
Last trimester of pregnancy is associated with increased abdominal pressure and this forces gastric contents into oesophagus
Heartburn subsides in the last months of pregnancy as uterus descends into pelvis

Question 28

What are the potential long term effects of GORD?

Answer 28

Oesophagitis, oesophageal strictures
Squamous cell carcinoma
Barrett’s syndrome - this may predispose someone to oesophageal adenocarcinoma
Oesophageal ulcer
Manometry will be ordered if you have symptoms of:
Heartburn or nausea after eating (GORD)
Problems swallowing [feeling that food is stuck behind the breast bone (achalasia)]

Question 29

How can you manage GORD?

Answer 29

Life-style changes - raise head of bed at night, weight loss, modify food
↓ Intake of foods and drink which cause symptoms
Anti-reflux surgery (fundoplication – wrap fundus around LOS)
Take antacids
H2 receptor antagonists and proton pump inhibitors
Metoclopramide/domperidone – may enhance peristalsis and help gastric acid clearance
Fundoplication can cause dysphagia as it reduces the distensibility of LOS

Question 30

What lifestyle changes help GORD?

Answer 30

Some people need to avoid large meals
Lose weight (if overweight)
Avoid foods that increase gastric acidity
Avoid foods that slow gastric emptying
Avoid lying down after meals - elevate the head of the bed
Avoid some drugs and smoking
Decease fat intake
Basically, if you know what aggravates the symptoms, you can try to implement life-style changes that may help alleviate the onset

Question 31

How do antacids help GORD?

Answer 31

Neutralise gastric acid; ↑ pH of gastric lumen
Inhibit peptic activity and stop acid secretion
But
Magnesium salts→ diarrhoea
Aluminium salts→ constipation
Use a mixture of 2 to ensure bowel function
Combine alginates (e.g. Gaviscon) with antacids for oesophageal reflux
Alginic acid + saliva form a raft which floats on content of gastric lumen and protects the oesophageal mucosa from reflux
All of the above agents ↓ acid secretion and help heal the ulcer, but removal of H. pylori is essential to stop ulcer returning.

Question 32

Why study oesophageal disorder?

Answer 32

Complications of GORD
Oesophagus has squamous mucosa
Acid reflux → desquamation of oesophageal cells (injury of squamous mucosa)
↑ cell loss → basal cell hyperplasia
Excessive desquamation → ulceration
Ulcers may haemorrhage, perforate or heal by fibrosis with strictures
This leads to Barrett’s oesophagus and oesophageal cancer