Lecture 6; Oesophageal function

Question 1

Describe the oesophagus;

Answer 1

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

Question 2

Are sphincters generally closed or open etc?

Answer 2

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

Question 3

Describe the process of swallowing the upper oesophagus;

Answer 3

• <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.

Question 4

What does UOS do?

Answer 4

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

Question 5

Describe the muscle of the oesophagus;

Answer 5

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

Question 6

What is primary and secondary peristalsis?

Answer 6

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)

Question 7

Describe peristalsis and the muscle layers;

Answer 7

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

Question 8

Describe the innervation of the oesophagus;

Answer 8

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

Question 9

Describe the characteristics of the LOS function;

Answer 9

• 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

Question 10

When else does LOS relax?

Answer 10

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

Question 11

What are the phases of swallowing?

Answer 11

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

Question 12

What is the oral phase of swallowing?

Answer 12

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

Question 13

What is the pharyngeal phase of swallowing?

Answer 13

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

Question 14

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

Answer 14

• Mouth - Upper airway (nose) - Lower airway (trachea)

Question 15

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

Answer 15

• 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

Question 16

What is the oesophageal phase?

Answer 16

• UOS relaxes - Bolus enters oesophagus - Oesophageal peristalsis initiated

Question 17

Where is swallowing controlled?

Answer 17

• Cortex and brainstem

Question 18

How is the brainstem involved in swallowing?

Answer 18

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

Question 19

When do most gastro-oesophogeal episodes occur?

Answer 19

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

Question 20

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

Answer 20

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

Question 21

What is a hiatus hernia?

Answer 21

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

Question 22

Why does heartburn occur?

Answer 22

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

Question 23

Whats the name of the disorder for gastric reflux?

Answer 23

GORD Gastric oesophageal reflux disorder

Question 24

What are some complications of GORD?

Answer 24

Reflux oesophagitis Oesophageal stricture Barretts oesophagus

Question 25

What can reflux oesophagitis lead to? other causes?

Answer 25

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

Question 26

What is oesophageal stricture?

Answer 26

- 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)

Question 27

What is barretts oesophagus?

Answer 27

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

Question 28

What are the two types of oesophageal cancer?

Answer 28

Adeoncarcinoma (GORDS, Barretts are risk) SqCC

Question 29

What causes motility disorders of the oesophagus?

Answer 29

- Issues with smooth muscle innervation or direct smooth muscle damage.

Question 30

What are 4 ways the oesophagus can be examined?

Answer 30

Gastroscopy Barium swallow 24hr pH study Manometry (pressure)

Question 31

Answer 31

Squamocolumnar junction a.k.a Z line

Question 32

What are we looking at? symptoms?

Answer 32

Severe reflux oesophigitis

Question 33

What are we looking at?

Answer 33

Peptic stricture

Question 34

What are we looking at?

Answer 34

Barrett's oesophagus

Question 35

What are we looking at?

Answer 35

Oesophageal candidiasis White plaques

Question 36

What are we looking at and what causes it?

Answer 36

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

Question 37

What are we looking at and what are potential causes?

Answer 37

Ulceration Herpes simplex virus Cytomegalovirus Pill-induced; Doxycycline, bisphosphonates

Question 38

What are we looking at?

Answer 38

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

Question 39

What are we looking at?

Answer 39

Stricture

Question 40

What are we looking at?

Answer 40

Oesophageal cancer

Question 41

Whats this? what causes this?

Answer 41

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.

Question 42

What have we got here? and whats it eitiology?

Answer 42

Diffuse oesophageal spasm - Non-peristaltic or simultaneous onset of contractions in the oesophagus

Question 43

What is this and its causes?

Answer 43

Achalasia - Degeneration of nerves in the oesophagus (Ganglionic cells in myenteric plexus) - Loss of inhibitory neurons in LOS that switch off tonic contraction

Question 44

What is this?

Answer 44

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