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SGUL - Physiology 1 > Oesophagus and its Disorders > Flashcards

Oesophagus and its Disorders Flashcards

1
Q

Describe the anatomy of the oesophagus.

A
  • fibromuscular tube of striated squamous epithelium
  • posterior to the trachea/beneath cricoid cartilage
  • begins at the end of the laryngopharynx and joins the stomach a few centimetres from the diaphragm (at the cardiac orifice)
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2
Q

What promotes the transport of ingested food into the stomach?

A
  • Relaxation of the sphincters (UOS and LOS).
  • Contraction and relaxation of the oesophagus
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3
Q

Describe the two sphincters of the oesophagus.

A
  • UOS (upper oesophageal sphincter)
  • LOS (lower oesophageal sphincter)
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4
Q

Describe the UOS.

A
  • Striated muscle
  • Musculo-cartilaginous structure
  • Constricted to avoid air entering the oesophagus.
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5
Q

Describe the LOS.

A
  • Smooth muscle
  • High-pressure area.
  • Has extrinsic and intrinsic components
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6
Q

What are the intrinsic components of the LOS?

A

Oesophageal muscles, under neurohormonal influence

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7
Q

What are the extrinsic components of the LOS?

A

Diaphragm muscle

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8
Q

Describe the intrinsic components of the LOS. PART 1

A
  • Thick, circular smooth muscle layers.
  • Clasp-like, semicircular smooth muscle fibres (on the right-hand side) giving myogenic activity but less ACh-responsive
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9
Q

Describe the intrinsic components of the LOS. PART 2

A

Sling-like, oblique gastric (angle of His) muscle fibres on the left-hand side
- works with clasp-like smooth muscle fibres to help prevent regurgitation - responsive to cholinergic innervation

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10
Q

Why is reflux common in infants?

A

Poorly developed Angle of His

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11
Q

Describe the extrinsic components of the LOS. PART 1

A
  • Crural diaphragm encircles the LOS
  • Diaphragm forms channel through which the oesophagus enters the abdomen.
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12
Q

Describe the extrinsic components of the LOS. PART 2

A
  • Fibres of the crural portion of the diaphragm posses a ‘pinchcock-like’ action
  • Stops reflux of acidic chyme into the oesophagus
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13
Q

Describe the neural innervation of the oesophageal sphincters.

A
  • acetylcholine: contraction of intrinsic sphincters
  • NO, VIP: relax the intrinsic sphincters
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14
Q

Describe the neural innervation of the upper part of the oesophagus.

A
  • Made up of striated muscle
  • Supplied by somatic motor neurons of the vagus nerve without interruptions (i.e vagus and splanchnic nerve)
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15
Q

Describe the neural innervation of the lower part of the oesophagus.

A
  • Made up of smooth muscle
  • Innervated by visceral motor neurons of the vagus nerve with interruptions
  • Synapse with postganglionic neurons; cell bodies in the oesophagus and splanchnic plexus
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16
Q

Describe upper oesophageal motor innervation.

A
  • Innervated directly by the somatic efferent cholinergic fibres of the vagus nerve
  • Originate from the nucleus ambiguus (releasing stimulatory ACh).
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17
Q

Describe distal oesophageal motor innervation.

A
  • Preganglionic vagus nerve fibres from the dorsal motor nucleus.
  • ACh affects post-ganglionic neurons in the myenteric plexus
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18
Q

What are the two types of post-ganglionic neurons in the myenteric plexus affected by ACh?

A

Excitatory cholinergic neurons and inhibitory nitrinergic neurons

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19
Q

List some functions of the oesophagus.

A
  • swallowing (deglutition)
  • conveys food and fluids from the pharynx to the stomach
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20
Q

Describe the coordination of swallowing. PART 1

A

Triggered by afferent impulses in the trigeminal, glossopharyngeal and vagus nerves.

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21
Q

Describe the coordination of swallowing. PART 2

A
  • Efferent impulses pass to the pharyngeal musculature and the tongue
  • Trigeminal, facial and vagus nerves supply the tongue muscles
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22
Q

Describe the coordination of swallowing. PART 3

A
  • Integration of these impulses occurs in the NTS, the nucleus ambiguus (NA) and the dorsal vagal nucleus (DVN).
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23
Q

How is swallowing initiated?

A
  • VOLUNTARY actions, where material collected on tongue and push it backwards into the pharynx
  • waves of INVOLUNTARY contractions push the material into the oesophagus
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24
Q

What supplementary events occur during swallowing? PART 1

A
  • inhibition of respiration, so the nasopharynx is closed off
  • closure of the glottis (around the vocal cords) by the epiglottis
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25
Q

What supplementary events occur during swallowing? PART 2

A
  • ring of peristaltic waves behind the material move it towards the stomach
  • second wave of peristalsis
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26
Q

Why is secondary peristalsis necessary?

A

A lot of food material does not reach the stomach after the first peristaltic wave.

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27
Q

What causes secondary peristalsis?

A
  • Stimulation of receptors upon distention of the lumen of the oesophagus by the food
  • Causes repeated waves of peristalsis
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28
Q

What prevents the reflux of gastric contents?

A
  • LOS (closes after material passes)
  • ‘pinchcock’ effect of the diaphragmatic sphincter on the lower oesophagus
  • plug-like action of the mucosal folds in the cardia
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29
Q

Expand on the pathophysiology of achalasia. PART 1

A
  • impaired LOS relaxation
  • can be accompanied by impaired peristalsis (sphincter spasms)
  • foods and liquids fail to reach the stomach (delayed emptying of LOS)
30
Q

Expand on the pathophysiology of achalasia. PART 2

A
  • dilation of the oesophageal body with distal narrowing
  • long periods of sporadic dysphagia (difficulty swallowing)
  • regurgitation of food
31
Q

List some causes of achalasia. PART 1

A
  • disorders of peristalsis in oesophagus
  • damage to the innervation of the oesophagus
32
Q

List some causes of achalasia. PART 2

A
  • degenerative lesions of the vagus nerve, and loss of the myenteric plexus ganglionic cells in the oesophagus
33
Q

List some symptoms of achalasia.

A
  • dysphagia
  • vomiting
  • heartburn
34
Q

What are two tests used in the diagnosis of achalasia?

A
  • BARIUM RADIOGRAPHY: allows for the evaluation of the mouth, pharynx and oesophagus
  • OESOPHAGEAL MANOMETRY: checks to see if the oesophagus is contracting/relaxing properly
35
Q

What does low LOS pressure suggest?

A

GORD

36
Q

What do high LOS pressures suggest?

A

<26 mmHg = normal
>100 mmHg = achalasia

37
Q

What would normal results of oesophageal manometry show?

A
  • pressure of the muscle contractions that move food down the oesophagus is normal
  • muscle contractions follow a normal pattern down the oesophagus
38
Q

What would abnormal results of oesophageal manometry show?

A
  • presence of muscle spasms in the oesophageal body
  • presence of weak contractions along the length of the oesophagus
39
Q

Describe reflux in normal individuals.

A
  • Brief, and relatively infrequent.
  • Often occurs after meals in normal individuals (due to transient spontaneous LOS relaxation).
  • Usually stimulates salivation.
40
Q

What is the effect of saliva?

A

Natural antacid - dilutes and neutralises the refluxed gastric contents.

41
Q

What is GORD?

A

Gastro-Oesophageal Reflux Disease.
- Reflux is more frequent and troublesome.
- Low rate of salivation.

42
Q

What is the effect of a low rate of saliva in GORD?

A
  • Lack of ability to swallow own saliva
  • Prolongation of contact of the refluxed material with the oesophagus.
  • Results in oesophageal irritation and damage.
43
Q

List some causes of reflux in those with GORD.

A
  • transient spontaneous LOS relaxation (TSR)
  • resting LOS tone is too weak to resist the pressure within the stomach
  • sudden relaxation of the LOS that isn’t induced by swallowing
44
Q

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

A
  • weak or uncoordinated oesophageal contractions
  • length of time the oesophagus is exposed to gastric acid
  • amount of pressure placed on the anti-reflux barrier
45
Q

What are some factors associated with GORD?

A
  • pregnancy/obesity
  • fat, chocolate, coffee or alcohol ingestion
  • cigarettes
  • drugs (eg. anticholinergic agents, calcium channel clockers and nitrate drugs)
46
Q

What are some symptoms of GORD?

A
  • heartburn and acid regurgitation/decreased acid clearance
  • waking up at night (due to larynx irritation)
  • dysphagia (difficulty swallowing)
47
Q

How would you investigate GORD?

A
  • low dose proton pump inhibitor (PPI)
  • upper GI endoscopy
  • manometry
  • 24-hour ambulatory pH monitoring
48
Q

How does pregnancy affect GORD? PART 1

A
  • Foetus increases the pressure on the abdominal contents.
  • Pushes the terminal segments of the oesophagus into the thoracic cavity.
49
Q

How does pregnancy affect GORD? PART 2

A
  • Last trimester of pregnancy is associated with increased abdominal pressure
  • Forces gastric contents into the oesophagus.
  • Heartburn subsides in the last months as the uterus descends into the pelvis.
50
Q

What are some potential long-term effects of GORD?

A
  • oesophagitis (inflammation)
  • Barrett’s Syndrome - this may predispose someone to oesophageal adenocarcinoma
  • oesophageal ulcer
51
Q

Describe the management and drug treatment of GORD. PART 1

A
  • Lifestyle changes e.g losing weight, avoiding food that increases gastric acidity, that slow gastric emptying, avoiding drugs and smoking, etc.
52
Q

Describe the management and drug treatment of GORD. PART 2

A
  • Anti-reflux surgery (fundoplication, where you wrap the fundus around the LOS).
  • Taking antacids, H2-receptor antagonists and proton pump inhibitors.
53
Q

Describe a possible problem with the use of antacids in the treatment of GORD.

A
  • Neutralise gastric acid, increasing the pH of the gastric lumen.
  • Inhibit peptic activity and stop acid secretion.
  • Contain magnesium salts cause diarrhoea while aluminium salts cause constipation.
54
Q

What happens if GORD becomes more serious? PART 1

A
  • Oesophagus naturally has squamous mucosa
  • Acid reflux could lead to the desquamation of oesophageal cells.
  • Increased cell loss causes basal cell hyperplasia.
55
Q

What happens if GORD becomes more serious? PART 2

A
  • Excessive desquamation causes ulceration.
  • Ulcers may haemorrhage, perforate or heal by fibrosis with strictures.
  • Leads to Barrett’s oesophagus and oesophageal cancer.
56
Q

What is the angle between the cardiac orifice and the fundus called?

A

→ Angle of His

57
Q

What is the LOS for?

A

→ Remains open as long as swallowing is occurring
→ Close to prevent reflux of the stomach contents into the oesophagus

58
Q

What is swallowing difficulty caused by?

A

→ Inability of the UOS to open
→ Discoordination of the timing between opening of UOS and pharyngeal push of the ingested bolus

59
Q

What do circular muscles act as and why?

A

→ 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

60
Q

What is a diffuse oesophageal spasm?

A

→ Chest pain coming from the oesophagus

61
Q

What is oesophageal spasm?

A

→ Abnormal oesophageal contractions
→ Food is not effectively reaching the stomach

62
Q

What is reflux?

A

→ retrograde movement of gastric content into the oesophagus due to the relaxation of the LOS

63
Q

Why do you get heartburn in the absence of pregnancy?

A

→May occur in some individuals upon eating large meals
→Less efficient LOS

64
Q

What happens to gastric contents during heartburn?

A

→episodically refluxed into the oesophagus

65
Q

What can happen as a result of heartburn?

A

→Ulcer
→ scarring
→obstruction or perforation of the lower oesophagus

66
Q

When is manometry ordered?

A

→Heartburn or nausea after eating GORD
→Problems swallowing

67
Q

What do Metoclopramide/domperidone do?

A

→enhance peristalsis and help gastric clearance

68
Q

What do you combine with alginates for reflux?

A

→ Combine alginates (e.g. gaviscon) with antacids for oesophageal reflux

69
Q

What do alginic acid and saliva form?

A

→Alginic acid + saliva form a ‘raft’ which floats on content of gastric lumen and protects the oesophageal mucosa from reflux

70
Q

What is essential to stop the ulcer returning?

A

Removal of H Pylori

SGUL - Physiology 1 (68 decks)

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