Oesophagus and its disorders Flashcards
What is the oesophagus?
→ Fibromuscular tube of striated squamous epithelium
Where is the oesophagus?
→ Posterior to the trachea
→ Beneath the cricoid cartilage
What does the oesophagus connect?
→ Begins at the end of the laryngopharynx and joins the stomach a few cm from the diaphragm
What is the oesophagus wall made from?
→ Striated muscle in the upper part
→ Smooth muscle in the lower part
→ Mixture of the two in the middle
What is the angle between the cardiac orifice and the fundus called?
→ Angle of His
What is the function of the angle of His?
→ Prevents the reflux of the contents of the stomach into the oesophagus
What is the function of the oesophagus?
→ Transports food to the stomach
→ Secretes mucus
What promotes the ingestion of food into the stomach?
→ Relaxation of UOS and LOS sphincters
→ Involves contraction and relaxation of the oesophagus
→ highly coordinated muscular process
What is the UOS for?
→ Relaxes to allow food through and closes to prevents air entering the oesophagus
What is the LOS for?
→ Remains open as long as swallowing is occurring
→ Close to prevent reflux of the stomach contents into the oesophagus
What kind of structure and muscle does the UOS have?
→ Musculo-cartilaginous structure
→ Striated muscle
What are the intrinsic and extrinsic components of the LOS?
INTRINSIC
→ Oesophageal muscles which are under neurohormonal influence
EXTRINSIC
→ Diaphragm muscles
What are the intrinsic components of the LOS?
→ Thick circular smooth muscle layers
→ Clasp like semi circular smooth muscle
→ Sling like oblique gastric
What activity do the clasp like muscles have?
→ Myogenic but less ACh responsive
How do the sling-like oblique gastric muscles prevent regurgitation?
→ Works in concert with semicircular smooth muscle
→ Response to cholinergic innervation
Why is reflux common in infants?
→ The angle of His is poorly developed
→ Forms a vertical junction with the stomach
What does the crural diaphragm form?
→ encircles the LOS
→ forms a channel through which the oesophagus enters the abdomen
→ Forms the oesophageal hiatus
What kind of action does the crural diaphragm possess?
→ Pinchcock like
What controls the tone of the LOS?
→ Involvement of cholinergic
→ NANC
What causes the intrinsic sphincters to contract?
→ Acetylcholine
→ SP
What causes the intrinsic sphincters to relax?
→ NO and VIP
What is the upper part of the oesophagus supplied by?
→ Somatic motor neurons of vagus nerves without interruption
→Splanchnic nerves
What is the lower part of the oesophagus innervated by?
→ Visceral motor neurons of vagus nerves with interruptions
How is sensory information integrated?
→ Sensory information is sent to the NTS
→ Integration occurs between NTS, nucleus ambiguus and vaso vagal nucleus
→ Food makes its way down
→ UOS relaxes
→ mediated by NO and VIP
→ Information gets sent to LOS via vagus nerve
→ ACh allows contraction to occur
What are the functions of the oesophagus?
→ Swallowing
→ Conveys food from the pharynx to the stomach
→ Efferent impulses pass to the pharyngeal musculature and the tongue
→ Integration of impulses in the NTS, nucleus ambiguus and DVN
By what impulses is swallowing triggered by?
→ trigeminal
→ glossopharyngeal
→ Vagus
How is swallowing initiated?
1) voluntary
→collect material on tongue and push it backwards into the pharynx
2) Waves of involuntary contraction push material into oesophagus
Where does food move?
→ Mouth
→ Oropharynx
→ Laryngopharynx
→ Oesophagus
What are the reflex responses initiated during swallowing?
→Inhibition of respiration
→ nasopharynx is closed off
→ Closure of the glottis by the epiglottis
→Ring of peristaltic waves behind the material move it towards the stomach
→ Second wave of peristalsis moves the food along
What is swallowing difficulty caused by?
→ Inability of the UOS to open
→Discoordination of the timing between opening of UOS and pharyngeal push of the ingested bolus
What causes repeated waves of peristalsis?
→ Stimulation of receptors upon distension of the lumen of the oesophagus by food
What prevents the reflux of gastric contents?
→ The LOS closes after the material has passed
→ Pinchcock effect of the diaphragmatic sphincter on the lower oesophagus
→ Plug like action of the mucosal folds in the cardia
What do circular muscles act as and why?
→ Act as valves to control the movement of the food mass aborally
→ Prevents reflux by forming an opening when relaxed and closing completely when contracted
What is achalasia?
→ Disorders of motility or peristalsis
What is a diffuse oesophageal spasm?
→ Chest pain coming from the oesophagus
What is oesophageal spasm?
→ Abnormal oesophageal contractions
→ Food is not effectively reaching the stomach
What causes Achalasia?
→ Impaired LOS relaxation
→ Accompanied by impaired peristalsis
What happens as a result of achalasia?
→ Food and liquids fail to reach the stomach - delayed opening of LOS
→ Dilatation of the oesophageal body with distal narrowing
→ birds beak appearance
→ Sporadic dysphagia
→ Regurgitation of food
What are 3 symptoms of achalasia?
→ Heartburn
→ Vomiting
→ Dysphagia
What are the two ways to diagnose achalasia?
→Barium radiography : dilatation of oesophagus with beak deformity at the lower end
→Oesophageal manometry : absent peristalsis
What is normal LOS pressure?
< 26 mmHg is normal
What is achalasia LOS pressure?
> 100 mmHg
What is nutcracker achalasia LOS pressure?
> 200 mmHg
What are abnormal results of oesophageal manometry?
→Presence of muscle spasms in the oesophageal body
→Presence of weak contractions along the length of the oesophagus
→LOS pressure is less than 10 mmHg
What is reflux?
→retrograde movement of gastric content into the oesophagus due to the relaxation of the LOS
When does reflux occur in normal individuals?
→after meals
What does reflux stimulate?
→ Salivation
What does saliva do to gastric acid?
→dilutes and neutralizes refluxed gastric contents
What kind of a sensation does GORD cause and when?
→burning sensation in the chest after meals - angina like pain
What are factors that contribute to the severity of GORD?
→Weak or uncoordinated oesophageal contractions
Prolonged duration of contact of refluxed digestive contents with oesophagus
→Length of time that the oesophagus is exposed to gastric acid
Increase in gastric acid secretion coupled with the presence of bile in gastric contents → severe oesophageal damage
→Amount of pressure placed on the antireflux barrier
Reflux occurs after eating, lying down and when there is delayed gastric emptying
Impaired gastric emptying alone can cause severe GORD
What are factors associated with GORD?
→Pregnancy or obesity
→Fat, chocolate, coffee or alcohol ingestion
→Large meals, tomatoes, orange juice, onions
→Smoking
→Drugs
What is LOS tone like in GORD?
→Resting LOS tone is low or absent
What happens as a result of poor oesophageal peristalsis?
→Decreased clearance of acid
What are symptoms of GORD?
→heartburn and acid regurgitation
→ waking up at night
→ dysphagia
How do you investigate GORD?
→Low dose proton pump inhibitor
→Upper GI endoscopy
→Manometry
→24hr ambulatory pH monitoring
What does the presence of a fetus do to abdominal contents?
→increases pressure on abdominal contents
→Pushes terminal segments of oesophagus into thoracic cavity
What is the last trimester of pregnancy associated with?
→increased abdominal pressure and this forces gastric contents into the oesophagus
Why does heartburn subside in the last months of pregnancy?
→ uterus descends into pelvis
Why do you get heartburn in the absence of pregnancy?
→May occur in some individuals upon eating large meals
→Less efficient LOS
What happens to gastric contents during heartburn?
→episodically refluxed into the oesophagus
What can happen as a result of heartburn?
→Ulcer
→ scarring
→obstruction or perforation of the lower oesophagus
What are some long term effects of GORD?
→Oesophagitis, oesophageal strictures
→Squamous cell carcinoma
→Barrett’s syndrome - this may predispose someone to →oesophageal adenocarcinoma
→Oesophageal ulcer
When is manometry ordered?
→Heartburn or nausea after eating GORD
→Problems swallowing
How do you manage GORD?
→Lifestyle changes - raise head of bed at night, weight loss, modify food
→Decreased intake of foods and drink which cause symptoms
→Anti reflux surgery ( fundoplication - wrap fundus around LOS)
→Take antacids
What do Metoclopramide/domperidone do?
→enhance peristalsis and help gastric clearance
What can fundoplication cause?
→dysphagia as it reduces the distensibility of LOS
What do antacids do to gastric acid and pH?
→Neutralise gastric acid ↑ pH of gastric lumen
What do antacids do to peptic activity and acid secretion?
→Inhibit peptic activity and stop acid secretion
What do magnesium salts cause?
→diarrhoea
What do aluminum salts cause?
→ Constipation
What do you combine with alginates for reflux?
→ Combine alginates (e.g. gaviscon) with antacids for oesophageal reflux
What do alginic acid and saliva form?
→Alginic acid + saliva form a raft which floats on content of gastric lumen and protects the oesophageal mucosa from reflux
What is essential to stop the ulcer returning?
→ removal of H. pylori
