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Digestive MBChB 2 > Lecture 6; Oesophageal function > Flashcards

Lecture 6; Oesophageal function Flashcards

1
Q

Describe the oesophagus;

A

Pharynx, upper oesophogeal sphincter (UOS), upper 1/3 of oesophagus - striated muscle. Lower 2/3 of oesophagus, lower oesophageal spincter (LOS) - Smoother muscle

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2
Q

Are sphincters generally closed or open etc?

A

A sphincter is generally closed at rest in a state of tonic contraction, relaxing intermittently as required by normal physiological function

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3
Q

Describe the process of swallowing the upper oesophagus;

A
  • <1s - Skeletal muscle contract 30-40cm/s - Co-ordinated by medulla - UOS closure can raise pressure to 30-200mmHg - UOS relaxation occurs for <1s allowing, swallowing, belching and vomiting.
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4
Q

What does UOS do?

A
  • Decrease entry of air into oesophagus and insufflating (distending the stomach) - Reflux of contents in pharynx and larynx during oesophageal paristalsis - Gastric reflux
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5
Q

Describe the muscle of the oesophagus;

A

Upper 1/3 striated Skeletal muscle. Lower 2/3 Smooth muscle only

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6
Q

What is primary and secondary peristalsis?

A

Contraction above and below the bolus caused by swallowing (Primary). Secondary caused by stimulation of sensory receptors in the oesophagus by retained bolus or gastric acid (Not swollowing related)

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7
Q

Describe peristalsis and the muscle layers;

A

Circular muscle layer; Contraction above and relaxation below bolus Longitudinal muscle layer; Shortens oesophagus during peristalsis

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8
Q

Describe the innervation of the oesophagus;

A
  • Receives ENS input. - Submucosal plexus - Myenteric plexus (between muscle layers) Can function autonomously i.e reflexes Communicates with parasymp and symp branches of ANS.
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9
Q

Describe the characteristics of the LOS function;

A
  • Smooth muscle 2-4cm - 20-35mmHg when closed - LOS relaxes 1-2s after swallowing and lasts 5-10s before hypercontracting - Close anatomical relationship to squamo-columnar junction
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10
Q

When else does LOS relax?

A
  • LOS also relaxes transiently; - Release stomach air - Lying down (night time gastric reflux) Occurs regularly when upright mediated by vagus nerve
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11
Q

What are the phases of swallowing?

A

Oral Phase - Striated muscle (Voluntary) Pharyngeal phase - Striated muscle (Involuntary) Oesophogeal phase - Striated and smooth muscle (Involuntary)

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12
Q

What is the oral phase of swallowing?

A

Preparatory phase to form food bolus - Mastication - Enzymes - lubrication AND transfers food to pharynx Teeth and tongue work hard,

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13
Q

What is the pharyngeal phase of swallowing?

A
  • <1s - Bolus moves through pharynx at 30-40cm/s - UOS relaxes
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14
Q

What passages must be closed to achieve the pharyngeal phase of swallowing?

A
  • Mouth - Upper airway (nose) - Lower airway (trachea)
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15
Q

Describe how the passages are closed off during the pharyngeal phase;

A
  • Tongue pushes against palate closing oropharynx - Soft palate elevates, proximal pharyngeal wall moves medially closes off upper airway (nasopharynx) - Epiglottis swings down, vocal cords and arytenoids adduct, seals off lower airway
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16
Q

What is the oesophageal phase?

A
  • UOS relaxes - Bolus enters oesophagus - Oesophageal peristalsis initiated
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17
Q

Where is swallowing controlled?

A
  • Cortex and brainstem
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18
Q

How is the brainstem involved in swallowing?

A

Brainstem receives sensory input from receptors in posterior mouth and upper pharynx and also innervates swallowing muscles via cranial nerves.

19
Q

When do most gastro-oesophogeal episodes occur?

A

During transient relaxation of the LOS. This is physiological but becomes pathological when too much gastric juice also refluxes into oesophagus causing symptoms / disease

20
Q

What can cause acid in the oesophagus i.e heart burn?

A

Disordered gastric motility - More acid in fundus of stomach

Hiatus hernia - Can result in reservoir of acid close to LOS or impair LOS function Impaired oesophageal peristalsis

Hypotensive LOS i.e not contracting tight enough - Caused by caffeine, alcohol, chocolate, fats.

Certain meds; Beta-blockers, nitrates, Ca chan blockers

21
Q

What is a hiatus hernia?

A

Hiatus = Opening in diaphragm (Diaphragm aids GO constriction.) Hiatus hernia is when stomach protrudes through hiatus.

22
Q

Why does heartburn occur?

A

Empty stomach pH can be 1-2, squamous epithelium not designed to handle this. Sensitivity highly variable

23
Q

Whats the name of the disorder for gastric reflux?

A

GORD Gastric oesophageal reflux disorder

24
Q

What are some complications of GORD?

A

Reflux oesophagitis Oesophageal stricture Barretts oesophagus

25
Q

What can reflux oesophagitis lead to? other causes?

A
  • Can develop ulceration (most common cause of oesophageal ulceration) Other causes of reflux oesophagitis; Radiation, alkali ingestion, infection i.e candida or herpes.
26
Q

What is oesophageal stricture?

A
  • Scarring from repeated acid exposure and ulceration - Can lead to difficulty swallowing (dysphagia) Oesophagus normally stretches to 2-2.5cm, dysphagia occurs with fibrous stricture (<2.5cm)
27
Q

What is barretts oesophagus?

A

Changes from squamous epithelium to columnar lines oesophageal epithelium (Intestinal metaplasia) Increases risk of cancer (adenocarcinoma) Present on endoscopy but needs biopsy confirmation

28
Q

What are the two types of oesophageal cancer?

A

Adeoncarcinoma (GORDS, Barretts are risk) SqCC

29
Q

What causes motility disorders of the oesophagus?

A
  • Issues with smooth muscle innervation or direct smooth muscle damage.
30
Q

What are 4 ways the oesophagus can be examined?

A

Gastroscopy Barium swallow 24hr pH study Manometry (pressure)

31
Q
A

Squamocolumnar junction a.k.a Z line

32
Q

What are we looking at? symptoms?

A

Severe reflux oesophigitis

33
Q

What are we looking at?

A

Peptic stricture

34
Q

What are we looking at?

A

Barrett’s oesophagus

35
Q

What are we looking at?

A

Oesophageal candidiasis

White plaques

36
Q

What are we looking at and what causes it?

A

Eosinophilic oesophagitis

Allergy mediated, patient might have history of atopy; asthma, hayfever, eczma

37
Q

What are we looking at and what are potential causes?

A

Ulceration

Herpes simplex virus

Cytomegalovirus

Pill-induced; Doxycycline, bisphosphonates

38
Q

What are we looking at?

A

Ring/web

Schatzki ring - distally, typically associated with hiatus hernia, aetiology uncertain

39
Q

What are we looking at?

A

Stricture

40
Q

What are we looking at?

A

Oesophageal cancer

41
Q

Whats this? what causes this?

A

Zenkers diverticulum, failure of UOS to relax may be mechanism.

Excessive pressure causes the weakest portion of the pharynx to balloon out.

More common in elderly.

42
Q

What have we got here? and whats it eitiology?

A

Diffuse oesophageal spasm

  • Non-peristaltic or simultaneous onset of contractions in the oesophagus
43
Q

What is this and its causes?

A

Achalasia

  • Degeneration of nerves in the oesophagus

(Ganglionic cells in myenteric plexus)

  • Loss of inhibitory neurons in LOS that switch off tonic contraction
44
Q

What is this?

A

Scleroderma

  • CT disease
  • Fibrosis of submucosa and muscle
  • Affects SM and Nerves, turning oesophagus into rubbery hose-pipie
  • Absent peristalsis, loss of LOS tone

= Dysphagia and severe reflux

Digestive MBChB 2 (31 decks)

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