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Digestive > 8 - Oesophageal Function > Flashcards

8 - Oesophageal Function Flashcards

1
Q

Describe the order of the structures food passes through

A

Oral cavity > pharynx/throat > upper oesophageal sphincter > oesophagus > lower oesophageal sphincter > stomach

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2
Q

What does the oesophagus do?

A

Long muscular tube that connects the mouth and pharynx to the stomach. It is for food bolus transport

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3
Q

Swallowing is a highly complex … that needs to be …. or else …. and ….

A

swallowing is a highly complex REFLEX that needs to be PRECISE or else it can lead to CHOCKING or ASPIRATION

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4
Q

What are the 3 phases of swallowing?

A
  1. Oral phase
  2. Pharyngeal phase
  3. Oesophageal phase
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5
Q

What swallowing phases are voluntary and which are involuntary?

A

Only the first oral phase is voluntary i.e. when you eat and open and close your mouth. Once it is in your mouth, swallowing is involuntary i.e. when there is saliva in your mouth when you sleep or are in a come, you swallow.

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6
Q

What kind of muscle is involved in each of the swallowing phases?

A

Oral - striated
Pharyngeal - striated
Oesophageal - striated and smooth

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7
Q

What is the neural control of swallowing?

A

Swallowing is controlled by both the brain cortex (invol) and the brainstem (vol)
> the swallowing centre in the brainstem receives sensory input form receptors in the posterior mouth and upper pharynx and innervates swallowing muscles via CRANIAL nerves

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8
Q

What are the 2 phases of the oral phase?

A

The preparatory phase and transfer phase

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9
Q

Preparatory phase?

A

Chewing and formation of the bolus
> mastication where solids are broken down into size, shape and consistency suitable for transport.
> teeth used for grinding
> tongue and cheeks used to position solids over the grinding surfaces
> saliva is used for lubrication and dissolving

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10
Q

Oral transfer phase?

A

Adequately prepared bolus is propelled by tongue to the back of the mouth and pharynx
> the tip of the tongue moves into contact with the HARD palate to close off the anterior oral cavity
> bolus is then pushed to the back of the mouth

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11
Q

What are the 3 parts of the pharynx/throat?

A

Nasopharynx - inferior to nasal cavity > soft palate
Oropharynx - soft palate > inferior oral cavity (right behind mouth)
Hypopharynx - inferior to oral cavity
(larynx is in trachea)

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12
Q

How long is the pharyngeal phase?

A

Less than 1 second (30-40cm/s)

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13
Q

What passages have to be closed during the pharyngeal phase?

A

The mouth, upper air way and lower airway (don’t want food in lungs/aspirate)

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14
Q

Describe the pharyngeal phase

A

The bolus enters the pharynx from the back of the mouth and exits as the upper oesophageal sphincter into the oesophagus

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15
Q

How does the pharyngeal phase occur?

A
  • the tongue pushes against the palate to seal the back of the mouth and oropharynx
  • the soft palate elevates and the proximal pharyngeal wall moves medially to seal off the upper airway and nasopharynx
  • the epiglottis swings down and the vocal cords and arytenoids adduct to seal off the lower airway/larynx/lower airway
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16
Q

What 3 structures work to protect the lower airway?

A
  • epiglottis (swings down)
  • vocal cords (adduct)
  • arytenoids (adduct)
    > means you can’t talk or breathe when you swallow, can masticate and talk
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17
Q

Is a sphincter usually closed or open?

A

A sphincter is usually in a state of tonic contraction causing it to close, relaxing intermittently as required by normal physiological function

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18
Q

What is the upper oesophageal sphincter?

A

The UOS is composed of a group of muscles. It acts as a barrier between the PHARYNX and OESOPHAGUS

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19
Q

What pressure is the UOS normally and why is this significant?

A

Normal pressure is 30-200mH, meaning the upper oesophageal sphincter is usually contracted and closed most of the time

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20
Q

What does the UOS prevent?

A
  • air distending the stomach (look pregnant)

- reflux on contents from the oesophagus into the pharynx and larynx during OESOPHAGEAL PERISTALSIS

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21
Q

When does the UOS sphincter relax?

A

Relaxes and opens when we swallow, belch or vomit (opens for only 0.5s)

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22
Q

What 3 muscles does the UOS consist of?

A
  1. Cricopharngeus
  2. Inferior pharyngeal constrictor
  3. Cervical oesophagus
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23
Q

How and why does the UOS open?

A
  1. Cricopharngeus relaxes
  2. Suprahyoid and thyrohoid muscles contract
  3. Pressure of descending bolus distending UOS
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24
Q

How long is the oesophagus?

A

Is 20-25cm from the UOS to the LOS

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25
Q

What are 3 unique things about its 4 tunic layers?

A

Mucosa contains stratified squamous sacrificial layers for physical protection
The upper 1/3 contains skeletal muscle
The lower 2/3 is only smooth muscle

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26
Q

Describe the oesophageal phase

A
  • begins as the UOS relaxes and the bolus enters the oesophagus and peristalsis is initiated
  • primary peristalsis
  • secondary peristalsis
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27
Q

What is primary peristalsis?

A

Primary peristalsis is initiated by swallowing. It is a continuation of the pharyngeal contraction wave, but is SLOW than the pharyngeal peristalsis at 3-5cm/s (not 30-40cm/s)

28
Q

What is secondary peristalsis?

A

Secondary peristalsis is initiated by distention of the oesophagus (when food is stuck or there is gastric acid in the oesophagus)
Stretch receptors are then stimulated which initiates LOCAL REFLEX response, triggering peristalsis
> i.e. it is INVOLUNTARY

29
Q

How is oesophageal peristalsis controlled?

A
  • ANS
  • enteric nervous system (plexi of nerves embedded in the wall of the GI tract i.e. myenteric and submucosal plexi
    > the enteric nervous system can work by itself/autonomously (co-ordination of reflexes) and communicates with the ANS
30
Q

Where is the myenteric nerve plexus?

A

IC plexus OL

31
Q

Difference between serosa and adventitia?

A
  • serosa (visceral peritoneum) is a smooth membrane that secretes serous solution for lubrication on a bed of CT
  • adventitia is a layer of CT that BINDS structures
32
Q

How does the IC and OL create peristalsis in the oesophagus?

A

IC - contracts above and relaxes below the bolus

OL - contracts in front of the bolus and shortens

33
Q

What is the junction called where the oesophagus ends?

A

Squamocolumnar junction / Z Line

  • it is the transition between stratified squamous and cuboidal/columnar epithelium
  • colour change and epithelium change
34
Q

What is the LOS?

A

Is just inferior the the squamocolumnar juntion/Z line. It is a specialised segment of SMOOTH muscle

35
Q

How does the pressure of the LOS compare to the UOS?

A

Is much lower at 20-35 compared to 30-200. Is contracted most of the time.

36
Q

How does relaxation and opening of the LOS occur?

A
  • it can be related OR unrelated to swallowing
  • the LOS starts to relax 1-2 seconds after swallowing, lasts 5-10 seconds, and then HYPERcontracts
  • ALSO relaxes transiently when NOT swallowing and may be physiological i.e. occurs at regular intervals ONLY when in an upright position, this is mediated by the vagus nerve and releases air from the stomach
37
Q

What are 4 ways to do an investigation on the oesophagus?

A
  1. Gastroscopy (examine lining)
  2. Barium Swallow (radio-contrast material and take x rays while swallowing)
  3. 24 hour pH study (catheter in oesophagus at LOS)
  4. Manometry (similar tp pH study but not for 24 hours, thin catheter with pressure sensor sits in the oesophagus)
38
Q

What are 3 categories of diseases in the oesophagus?

A

Structural
> visible changes, inflam, iscaemia/necrosis, ulceration, bleeding, narrowing, masses, diverticulum
Motility (abnormal contraction of the oesophageal muscles)
Functional
> disorder of motility, sensation and brain-gut dysfunction

39
Q

What is the pathophysiology of gastro-oesophageal Reflux Disease (GORD)

A

It is the movement of gastric contents into the oesophagus which contains acid and so erodes the oesophagus. The reflux occurs during normal transient relaxation of the LOS when air is let out of the stomach - this normal process becomes pathological when too much gastric acid refluxes and causes symptoms

40
Q

What are 3 other contributing mechanisms of GORD?

A
  1. HYPOtensive LOS (not contracting tight enough)
  2. hiatus hernia (not all)
  3. Impaired oesophageal peristalsis (results in reduced clearance)
41
Q

What can cause a hypotensive LOS?

A

Caffeine, alcohol, chocolate, fats, certain medications (beta blockers, nitrates, calcium channel blockers)

42
Q

What structure helps close the LOS?

A

The diaphragm - sits just above the LOS and adds additional support to constrict around the gastro-oesophageal junction

43
Q

Does GORD cause pain?

A

People ma or may NOT feel the reflux

44
Q

What is a hiatus hernia?

A
  • the hiatus is an opening in the diaphragm for the oesophagus to pass through and join the stomach
  • hernia = part of an organ protrudes through an opening in muscle/tissue that is meant to hold it in place
  • hiatus hernia = STOMACH passes through hiatus into chest as the GO junction has lost support from the diaphragm
45
Q

What causes the symptoms of gastro-oesophageal reflux disease?

A
  • the normal pH of the oesophageal mucosa is 6-7 so is sensitive to the gastric contents pH 1-2 (unless buffered by food)
  • the nerve fibres are sensitive to the low pH and give the sensation of BURNING
  • there are eventual complications of chronic acid exposure
46
Q

What are the symptoms of acid reflux?

A
  • heartburn/chest discomfort over the chest
  • regurgitation of food or liquid coming back up into the mouth
  • sour or bitter taste in mouth that may be worse soon after eating or lying down
  • can also be NO symptoms
47
Q

What are some complications of GORD?

A
  • GORD is a disease due to abnormal MOTILITY of the oesophagus (& stomach) but causes structural complications
    1. Reflux oesophagitis
    2. Peptic Stricture
    3. Barrett’s Oesophagus
    4. Cancer
48
Q

What is Reflux Oesophagitis?

A

Damage to the oesophageal mucosa by reflux of gastric contents leading to inflammation, ulceration and bleeding (haematemesis) and dysphagia (difficulty swallowing)
> can become severe and lead to scarring

49
Q

What is peptic stricture?

A

Prolonged inflammation of the oesophageal mucosa by longterm reflux leading to FIBROSIS and SCARRING

  • causes narrowing of the oesophagus (stricture)
  • which causes dysphagia
  • scarring often causes no symptoms/pain
50
Q

What causes and what is Barrett’s oesophagus?

A
  • Intestinal Metaplasia: stratified squamous transforms to cuboidal/columnar (gastric like) epithelium with goblet cells due to damage to oesophageal epithelium from chronic acid exposure in GORD
  • have an increased risk of oesophageal adenocarcinoma
51
Q

Who is Barrett’s common in?

A

Males over 50, increased BMI, smoker with chronic GORD

Common in NZ

52
Q

Besides GORD what else affects risk of Barretts?

A

Genetics, gender, race - an accumulation of genetic factors can also increase risk of adenocarcinoma from Barretts

53
Q

What is the evolution from Barrett’s to cancer?

A

squamous > chronic inflam > barretts metaplasia > low/high grade dysplasia > invasive adenocarcinoma

54
Q

What are the 2 types of oesophageal cancer?

A
  1. Adenocarcinoma (often consequence of Barrets and GORD, more distal at GO junction)
  2. Squamous cell carcinoma (alcohol, diet, smoking, higher in oes)
55
Q

Oesophageal Ring/Web?

A
  • structural disease
  • is a thin protuding mucosal membrane
  • schatzki ring is found distally and is commonly associated with hiatus hernia
  • can cause lumen to narrow and act like peptic stricture to cause problems swallowing
56
Q

Zenker’s Diverticulum (pharyngeal pouch)?

A
  • structural disease
  • excessive pressure causes the weakest portion of the pharynx to balloon out
  • common symptom is someone will cough something out they ate 5 days ago (was in pouch)
  • most common in the elderly
57
Q

What are the 2 types of strictures and what causes them?

A

peptic - reflux related
caustic - i.e. drink cleaning products
Can occur post-radiotherapy, post surgically, malignant
Causes swallowing problems

58
Q

Reflux oesophagitis?

A
  • structural disease

- results from GORD

59
Q

Oesophageal candidiasis?

A
  • structural disease
  • results in white plaques coating the oesophagus
  • common in people who use inhalers, elderly and the immune compromised
60
Q

Ulceration?

A
  • can be caused by herpes simplex virus, cytomegalovirus

- can be pill induced i.e. bisphosphonates

61
Q

Eosinophilic Oesophagitis?

A
  • characterised by RINGED appearance
  • where eosinophils invade the epithelium of the oesophagus and so is allergy mediated
  • often occurs in the YOUNG especially those with asthma, hay fever, eczema
62
Q

Oesophageal cancer?

A
  • common in people with history of chronic reflux/GORD or barretts (adenocarcinoma)
  • squamous cell carcinoma (smoking, diet, alcohol)
63
Q

What are motility disorders of the oesophagus?

A
  • they present with difficulty swallowing (dysphagia)
  • are more likely to have intermittent and variable symptoms
  • unlike structural may affect liquids as much as solids
  • often problem with the innervation to smooth muscle resulting in the loss of function/co-ordination or direct muscle damage
64
Q

Achalasia?

A
  • motility disorder
  • due to the DEGENERATION of nerves in the oesophagus (myenteric plexus and LOS inhibitory nerves - relax LOS so contracts strongly)
  • uncertain cause
  • results in the loss of peristalsis in the distal oesophagus and failure of LOS to relax
    > BIRDS BEAK
  • can inject botox into muscle to relieve symptoms
65
Q

Diffuse oesophageal spasm?

A
  • motility disorder
  • cork-screw oesophagus
  • is non-peristaltic or simultaneous onset of contractions
  • causes dysphagia and CHEST PAIN
66
Q

Nutcracker oesophagus?

A

STRONG contractions in peristalsis

67
Q

Scleroderma?

A
  • CT disease and motility disorder
  • hardening/fibrosis of the CT and skin of oesophagus
  • results in damage to submucosa, muscle, nerves
  • peristalsis is ABSENT with contractions weak and LOS has NO tone
  • causes inability to swallow and SEVERE reflux as oes has NO tone
  • dilated ‘hose pipe’

Digestive (24 decks)

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