Lecture 7 Flashcards
1
Q
List the structures involved with swallowing
A
Oral cavity Pharynx Upper oesophageal sphincter Oesophagus Lower oesophageal sphincter
2
Q
Why does swallowing need to be precise?
A
Choking
Aspiration
3
Q
What does aspiration mean?
A
When things for the wrong way, e.g. into the lungs.
4
Q
What is the risk of aspiration?
A
Pneumonia, which can be severe in people who have silent or recurrent aspiration
5
Q
What are the 3 phases of swallowing?
A
Oral
Pharyngeal
Oesophageal
6
Q
Describe the type of contraction and the type of muscle involved in each of the oral, pharyngeal, and oesophageal phases
A
Oral - voluntary, striated muscle
Pharyngeal - involuntary, striated muscle
Oesophageal - involuntary, striated and smooth muscle
7
Q
What is swallowing controlled by? What does this mean for people who have had strokes there?
A
Both cortex and brainstem. People who have had strokes in the cortex or brainstem can develop swallowing disorders.
8
Q
What structure does the oral phase of swallowing involve?
A
Oral cavity
9
Q
What is the superior, anterior, lateral, posterior, and inferior boundary of the oral cavity?
A
Superior: palate made up of hard and soft palate
Anterior and lateral: lips, cheek, body of tongue
Posterior: uvula (hangs down from soft palate), palatine tonsil, root of tongue, lingual tonsil
Inferior: hyoid muscles which support base of the tongue
10
Q
What are the two parts of the oral phase?
A
Preparatory phase: formation of bolus
Transfer phase: bolus propelled into pharynx
11
Q
What happens in the preparatory phase of the oral phase of swallowing?
A
Mastication
- Breaks down solids into size, shape and consistency suitable for transport
- Teeth grind the food
- Tongue and cheeks coordinate the movement so that solids are distributed evenly over the mouth and surfaces of teeth
- Saliva for lubrication and dissolving solids
12
Q
What happens in the transfer phase of the oral phase of swallowing?
A
Once bolus is adequately prepared, the tip of the tongue moves into contact with the hard palate, which closes off the anterior cavity. Bolus is pushed into the back of the mouth.
13
Q
What are the three parts that the pharynx is divided up into?
A
Nasopharynx: part of pharynx in contact with nasal cavity
Oropharynx: part of pharynx immediately behind the mouth
Hypopharynx: inferior to oral pharynx and leads into oes. Very close to larynx, which leads into the trachea.
14
Q
For how long does the pharyngeal phase last? Why?
A
Slightly less than 1s to ensure food doesn’t go the wrong way.
15
Q
What passages have to be closed during the pharyngeal phase of swallowing?
A
Mouth, upper airway, lower airway
16
Q
What are the events that occur during the pharyngeal phase of swallowing?
A
- Tongue pushes against palate to seal the back of the mouth (oropharynx) so that food doesn’t enter the nasal cavity
- Soft palate elevates and proximal pharyngeal wall moves medially to seal off the upper airway (nasopharynx)
- Epiglottis swings down and vocal cords and arytenoids adduct to seal off the lower airway
- Bolus descends through the pharynx by peristalsis at 30-40 cm/s
- UOS opens just before bolus reaches it
- Bolus leaves pharynx and enters oes
17
Q
What is the normal state of a sphincter? What does it do?
A
A sphincter is normally in a state of tonic contraction, relaxing intermittently as required by normal physiological functioning
18
Q
What is the UOS composed of?
A
Cricopharyngeus, inferior pharyngeal constrictor, cervical oes
19
Q
What is the state of the UOS most of the time? What is the normal pressure?
A
Closed
30-200 mmHg
20
Q
What does the UOS prevent?
A
Air insufflating (distending) the stomach while speaking Reflux of contents into pharynx and larynx during oesophageal peristalsis
21
Q
When does the UOS relax?
A
When swallowing, belching, or vomiting
22
Q
What factors open the UOS?
A
Cricopharyngeus relaxes
Suprahyoid and thyrohyoid muscles contract when swallowing to relax the sphincter
Pressure of descending bolus distends the UOS
23
Q
Where does the oes extend from and to?
A
UOS to LOS
24
Q
How long is the oes?
A
20-25 cm
25
What type of tissue is the mucosa of the oes?
Stratified squamous epithelium
26
What type of muscle is the upper third of the oes made up of? What about lower 2/3?
Upper 1/3: striated
| Lower 2/3: smooth
27
Which structures sit very close to the oes?
Cricoid
Aortic arch
Left main bronchus
Diaphragm
28
Describe the pathway of the aorta as it passes over the left main bronchus.
Aorta moves front to back over the left main bronchus and sits behind the oes
29
Where is cricopharyngeal muscle located?
At cricoid
30
Where does the oes leave the chest? What is this often seen as?
Oes leaves the chest through diaphragm. This is often seen as narrowing of the oes.
31
What are the events that occur during the oesophageal phase?
- UOS relaxes, bolus enters oes, oesophageal peristalsis initiated
- Primary peristalsis
- Secondary peristalsis
32
Describe primary peristalsis
- Initiated by swallowing
- Continuation of pharyngeal contraction wave
- Slower than pharyngeal peristalsis 3-5 cm/s
33
Describe secondary peristalsis
- Initiated by distension (e.g. food stuck or gastric acid)
- Stretch receptors stimulated, initiates local reflex response, triggering peristalsis
- Intent is to clear the oes of food or gastric acid
34
What is oesophageal peristalsis controlled by?
- Autonomic nervous system
| - Enteric nervous system
35
Describe the enteric nervous system of the oes
```
Plexus of nerves embedded in the wall of the GI tract
- Submucosal plexus
- Myenteric plexus
Can autonomously
Coordination of reflexes
Also communicates with ANS
```
36
What is the oes mostly covered by?
Adventitia.
37
What are intraperitoneal and retroperitoneal covered by?
Intra: Serosa
Retro: Adventitia
38
Describe the normal peristaltic wave?
Contraction occurs in a synchronous fashion from top to bottom.
39
What muscles is peristalsis of the oes controlled by?
Controlled by the circular muscles which contract above and relax below bolus in a cross-sectional manner and the longitudinal muscles then shorten the oes.
40
Where the LOS sit?
At the gastro-oesophageal junction
41
What is the LOS visualised by endoscopy as?
The squamo-columnar junction due to change in epithelium. Transition from stratified squamous (oes) to columnar (gastric). Also known as Z line.
42
Describe the LOS
Specialised segment of smooth muscle
43
What is the state of the LOs most of the time?
Contracted
| Normal pressure: 20-35 mmHg
44
When does the LOS relax?
- LOS begins to relax 1-2 s after swallowing, lasts 5-10 s followed by hypercontraction
- LOS also relaxes transiently when not swallowing at regular intervals and only in upright position to release air from the stomach, which leads to belching
45
What controls the intermittent relaxation of the LOS?
Vagus nerve
46
What are the 4 methods of investigation of the oes?
Gastroscopy
Barium swallow
24 hour pH study
Manometry
47
What happens in gastroscopy? What is it useful for?
Flexible telescope inserted into the mouth, oes, and into stomach
More useful for structural investigations
48
What is a barium swallow? What does it allow us to assess?
X-ray test, which allows us to examine the oes in motion as a person swallows. Allows us to assess the function and motility of the oes.
49
What occurs in a 24 hour pH study? What is it useful for?
Thin catheter is inserted into oes for 24 hours. Catheter sits just above the gastro-oesophageal junction. Any reflux activity is detected as a drop in pH of the distal oes. Tells us if there is excessive amount of reflux.
Useful for people whom you think may have reflux but either have unusual symptoms or can't be confident of the diagnosis.
50
What happens in manometry? What is it used to detect?
Patient performs swallow with water. Thin catheter with pressure sensors sits in oes between UOS and LOS. As the person swallows, the contraction is measured as a wave and you can determine whether the propagation is normal.
51
What are the different types of diseases of the oes?
Structural, dysmotility, functional
52
What are structural diseases? Give 8 examples of symptoms that can occur in structural diseases
```
Diseases that cause visible change
Inflammation
Ischaemia/necrosis
Ulceration
Bleeding
Narrowing
Masses
Diverticulum
```
53
What are dysmotility diseases?
Abnormal contraction of oesophageal muscles
54
What are functional diseases? Give an example
Disorder of motility, sensation, and brain-gut dysfunction
| Irritable bowel syndrome
55
What is gastro-oesophageal reflux?
Movement of the gastric contents into the oes
56
How does GORD develop?
Gastric contents contain acid, which is erosive to the oes. Reflux occurs during transient relaxation of LOS, which becomes pathological when too much gastric juice refluxes into oes causing symptoms or disease.
57
Why is the oes not structured to deal with gastric acid?
Does not have columnar epithelium
58
What are other contributing factors to GORD?
- Hypotensive LOS that is not contracting tight enough.
- Hiatus hernia
- Impaired oesophageal peristalsis
59
What are the causes for hypotensive LOS?
Can be born with this but is made worse by caffeine, alcohol, chocolate, certain medications (beta-blockers, nitrates, calcium channel blockers)
60
Normally, how does the diaphragm help support the LOS?
Normally after a meal, the stomach is filled with acid. The more food is consumes, the more the stomach will distend. The more it distends, the more pressure it places on the sphincter. Sphincter normally sits above the diaphragm and the diaphragm supports the sphincter to help it to remain shut. When the sphincter relaxes, you can have gastric acid refluxing into distal oes. The diaphragm acts as additional support, like a sphincter constricting around the GO junction.
61
What happens in hiatus hernia?
The stomach herniates through a weak point in the diaphragm and a part of it sits above the diaphragm. A section of the stomach acts as a chamber, and since it sits above the diaphragm, acid is able to reflux freely to the distal oes. Some gastric acid stays in the hiatus hernia. In addition, the LOS has lost its support from the diaphragm, which also weakens the sphincter.
62
What is a hiatus?
The hiatus is an opening in the diaphragm, where the oesophagus passes through to join the stomach.
63
What is a hernia?
A hernia is when part of an organ protrudes through an opening in the muscle/tissue that is meant to hold it in place.
64
What causes impaired oesophageal peristalsis?
Reduced clearance of acid by secondary peristalsis
65
What do the symptoms of GORD occur due to?
Gastric acid coming in contact with oes
- Oesophageal mucosa sensitive to acidic pH
- Normal pH in oes 6-7
- pH of gastric contents 1-2 (unless buffered by food)
- Nerve fibres in oes are sensitive to acidic pH, give sensation of “burning”
66
What are the symptoms of acid reflux?
- Heartburn/chest discomfort - Burning sensation or discomfort over bottom part of the chest
- Regurgitation
- Sour or bitter taste in mouth
- May be worse soon after eating or lying down (e.g. bedtime)
67
What structural complications can GORD cause?
- Reflux oesophagitis: Damage to oesophageal mucosa by reflux leading to inflammation, ulceration, and bleeding
- Peptic stricture: Prolonged inflammation of oesophageal mucosa by reflux can lead to fibrosis and scarring
- Barrett’s oesophagus
- Risk of cancer with chronic reflux
68
What symptoms are associated with oesophagitis?
- Linear areas of red and inflammation due to chronic exposure and damage by acid
- Pain/discomfort in chest
- Vomiting up blood: haematemesis
- Dysphagia: difficulty swallowing
- Over time, if the inflammation is not treated, it can cause narrowing. Called a peptic stricture if it is related to reflux
69
What can lead to Barrett's oes?
Damage to oesophageal epithelium by chronic acid exposure from GORD can lead to Barrett’s oesophagus
70
What occurs in Barrett's oes?
Oesophageal epithelium (squamous epithelium) transforms to become like gastric epithelium (columnar epithelium with goblet cells) to adapt to acid and protect itself. Known as intestinal metaplasia: defined as stratified epithelium converting to columnar epithelium. Pale regions become darker because they have transformed from squamous (pale) to columnar (darker).
71
In whom is Barrett's oes most common in?
Males, over 50, increased BMI, smoker with chronic GORD
72
What does Barrett's oes increase the risk of? Describe the process of this.
Oesophgeal adenocarcinoma
- Start off with intestinal metaplasia
- If reflux is not treated, increases risk of abnormal cells forming (low grade dysplasia)
- Over time, low grade abnormal cells become high grade (high grade dysplasia)
- High grade dysplasia becomes cancer
- There are potentially other factors as well, such as genetics, but the predominant driver of this transformation is ongoing reflux.
73
What is Barrett's oes usually diagnosed with?
Endoscopy
74
What are the two types of oesophageal cancer?
Adenocarcinma (adenoCa) and squamous cell carcinoma (SqCC)
75
What leads to risk of oesophageal adenoCa?
GORD - risk of Barrett's oes
76
What leads to increased risk of oesophageal SqCC
Smoking, alcohol, diet
77
In Western countries, which type of oesophageal cancer is more common?
AdenoCa, but this is declining due to treatment
78
What is the difference between the presentation of adenoCa and SqCC?
- adenoCa more likely to be in distal oes/GO junction
| - SqCC more likely higher up in oes
79
What is an oesophageal ring/web? What are the symptoms?
- Thin mucosal membrane around inner edge
- Schatzki ring – found distally, typically associated with hiatus hernia, aetiology uncertain
- Some people complain of dysphagia (difficulty swallowing)
80
What is Zenker's diverticulum also known as?
Pharyngeal pouch
81
How does Zenker's diverticulum form?
Formation of pouch at the back of the pharynx. Excessive pressure causes the weakest portion of the pharynx to balloon out.
82
What are the symptoms associated with Zenker's diverticulum?
- Poor swallowing
- Impaired relaxation of cricopharyngeus prior to swallowing
- Dysphagia
- Food getting stuck at the back of the throat
83
In whom is Zenker's diverticulum more common?
Elderly
84
What can cause strictures?
- Peptic: reflux-related
- Caustic: caustic injury
- Post-radiotherapy
- Post-surgical: anastomotic (describes the join where the surgery has occurred)
- Malignant
85
List examples of structural diseases of the oes.
```
Ring/web
Zenker's diverticulum
Stricture
Reflux oesophagitis
Oesophageal candidiasis
Ulceration
Eosinophilic oesophagitis
Oesophageal cancer
```
86
What happens in oesophageal candidiasis?
- Infections of the oes can cause structural or functional abnormalities
- White plaque coats oes
- Immunosuppressed people particularly vulnerable
87
What can cause ulceration of the oes?
```
Due to viruses:
- Herpes simplex virus
- Cytomegalovirus
Pill-induced when stuck in the oes
- Doxycycline
- Bisphosphonates
```
88
What happens in eosinophilic oesophagitis?
- Eosinophils infiltrate the epithelium of oes
- Allergy mediated
- Patient may have history of atopy: asthma, hayfever, eczema
- Circular lines run up and down oes. Can have fissuring (longitudinal lines)
89
What do motility disorders of the oes present wiht?
Difficulty swallowing (dysphagia). More likely to be intermittnet/variable symptoms. May affect liquids as much as solids.
90
What causes motility disorders?
Problem with innervation to smooth muscle (loss of function or coordination) or direct muscle change
91
What method is useful to diagnose motility disorders of the oes?
Manometry as the oes tends to be structurally healthy
92
List the motility disorders of the oes
Achalasia
Diffuse oesophageal spasm
Nutcracker oes
Scleroderma
93
What occurs in achalasia?
Degeneration of nerves in oes (myenteric plexus, LOS inhibitory nerves). Loss of peristalsis in distal oes due to damage to nerves and failure of LOS to relax with swallow. Oes becomes dilated because pressure increases as food is retained.
94
What is the characteristic appearance of achalasia on endoscopy or Barium meal?
Bird's beak
95
What is diffuse oesophageal spasm? What are the symptoms?
Non-peristaltic or simultaneous onset of contractions in the oes. Randomly occurring. Can cause dysphagia and chest pain.
96
What is diffuse oesophageal spasm also known as?
Corkscrew oes
97
What happens in nutcracker oes?
Normal peristalsis, but contractions very high amplitude
98
What happens in scleroderma?
Connective tissue disease. Hardening (fibrosis) of skin and CT. When oes is affected, damage occurs to submucosa, muscle layers, nerves and oes turns into a rubbery hose pipe. Peristalsis absent, contractions weak, LOS has no tone
99
What are the symptoms of scleroderma?
Dysphagia, severe reflux
