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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
What supplementary events occur during swallowing? PART 2
- ring of peristaltic waves behind the material move it towards the stomach - second wave of peristalsis
26
Why is secondary peristalsis necessary?
A lot of food material does not reach the stomach after the first peristaltic wave.
27
What causes secondary peristalsis?
- Stimulation of receptors upon distention of the lumen of the oesophagus by the food - Causes repeated waves of peristalsis
28
What prevents the reflux of gastric contents?
- 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
29
Expand on the pathophysiology of achalasia. PART 1
- impaired LOS relaxation - can be accompanied by impaired peristalsis (sphincter spasms) - foods and liquids fail to reach the stomach (delayed emptying of LOS)
30
Expand on the pathophysiology of achalasia. PART 2
- dilation of the oesophageal body with distal narrowing - long periods of sporadic dysphagia (difficulty swallowing) - regurgitation of food
31
List some causes of achalasia. PART 1
- disorders of peristalsis in oesophagus - damage to the innervation of the oesophagus
32
List some causes of achalasia. PART 2
- degenerative lesions of the vagus nerve, and loss of the myenteric plexus ganglionic cells in the oesophagus
33
List some symptoms of achalasia.
- dysphagia - vomiting - heartburn
34
What are two tests used in the diagnosis of achalasia?
- 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
What does low LOS pressure suggest?
GORD
36
What do high LOS pressures suggest?
<26 mmHg = normal >100 mmHg = achalasia
37
What would normal results of oesophageal manometry show?
- pressure of the muscle contractions that move food down the oesophagus is normal - muscle contractions follow a normal pattern down the oesophagus
38
What would abnormal results of oesophageal manometry show?
- presence of muscle spasms in the oesophageal body - presence of weak contractions along the length of the oesophagus
39
Describe reflux in normal individuals.
- Brief, and relatively infrequent. - Often occurs after meals in normal individuals (due to transient spontaneous LOS relaxation). - Usually stimulates salivation.
40
What is the effect of saliva?
Natural antacid - dilutes and neutralises the refluxed gastric contents.
41
What is GORD?
Gastro-Oesophageal Reflux Disease. - Reflux is more frequent and troublesome. - Low rate of salivation.
42
What is the effect of a low rate of saliva in GORD?
- Lack of ability to swallow own saliva - Prolongation of contact of the refluxed material with the oesophagus. - Results in oesophageal irritation and damage.
43
List some causes of reflux in those with GORD.
- 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
What are some factors that could contribute to the severity of GORD?
- 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
What are some factors associated with GORD?
- pregnancy/obesity - fat, chocolate, coffee or alcohol ingestion - cigarettes - drugs (eg. anticholinergic agents, calcium channel clockers and nitrate drugs)
46
What are some symptoms of GORD?
- heartburn and acid regurgitation/decreased acid clearance - waking up at night (due to larynx irritation) - dysphagia (difficulty swallowing)
47
How would you investigate GORD?
- low dose proton pump inhibitor (PPI) - upper GI endoscopy - manometry - 24-hour ambulatory pH monitoring
48
How does pregnancy affect GORD? PART 1
- Foetus increases the pressure on the abdominal contents. - Pushes the terminal segments of the oesophagus into the thoracic cavity.
49
How does pregnancy affect GORD? PART 2
- 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
What are some potential long-term effects of GORD?
- oesophagitis (inflammation) - Barrett’s Syndrome - this may predispose someone to oesophageal adenocarcinoma - oesophageal ulcer
51
Describe the management and drug treatment of GORD. PART 1
- Lifestyle changes e.g losing weight, avoiding food that increases gastric acidity, that slow gastric emptying, avoiding drugs and smoking, etc.
52
Describe the management and drug treatment of GORD. PART 2
- Anti-reflux surgery (fundoplication, where you wrap the fundus around the LOS). - Taking antacids, H2-receptor antagonists and proton pump inhibitors.
53
Describe a possible problem with the use of antacids in the treatment of GORD.
- 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
What happens if GORD becomes more serious? PART 1
- Oesophagus naturally has squamous mucosa - Acid reflux could lead to the desquamation of oesophageal cells. - Increased cell loss causes basal cell hyperplasia.
55
What happens if GORD becomes more serious? PART 2
- Excessive desquamation causes ulceration. - Ulcers may haemorrhage, perforate or heal by fibrosis with strictures. - Leads to Barrett’s oesophagus and oesophageal cancer.
56
What is the angle between the cardiac orifice and the fundus called?
→ Angle of His
57
What is the LOS for?
→ Remains open as long as swallowing is occurring → Close to prevent reflux of the stomach contents into the oesophagus
58
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
59
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
60
What is a diffuse oesophageal spasm?
→ Chest pain coming from the oesophagus
61
What is oesophageal spasm?
→ Abnormal oesophageal contractions → Food is not effectively reaching the stomach
62
What is reflux?
→ retrograde movement of gastric content into the oesophagus due to the relaxation of the LOS
63
Why do you get heartburn in the absence of pregnancy?
→May occur in some individuals upon eating large meals →Less efficient LOS
64
What happens to gastric contents during heartburn?
→episodically refluxed into the oesophagus
65
What can happen as a result of heartburn?
→Ulcer → scarring →obstruction or perforation of the lower oesophagus
66
When is manometry ordered?
→Heartburn or nausea after eating GORD →Problems swallowing
67
What do Metoclopramide/domperidone do?
→enhance peristalsis and help gastric clearance
68
What do you combine with alginates for reflux?
→ Combine alginates (e.g. gaviscon) with antacids for oesophageal reflux
69
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
70
What is essential to stop the ulcer returning?
Removal of H Pylori

SGUL - Physiology 1 (68 decks)

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