Esophagus (Week 10) Flashcards
How long is the esophagus?
~ 25cm
Where is the esophagus located?
posterior to trachea
begins at inferior end of laryngopharynx and ends in superior portion of stomach
The esophagus pierces the diaphragm through the ______________
esophageal hiatus
What type of cells are in the epithelium of the esophagus?
squamous stratified
What is the name of the resident dendritic cells that reside in the esophagus’ epithelium?
Langerhans cells
Lymphoid nodules (containing B cells and T cells) are found in the ____________ of the esophagus
lamina propria
Cardiac glands, that secrete mucous to protect the esophagus, are found where?
lamina propria
Note: there are 2 clusters (near pharynx and stomach)
What type of connective tissue is found in the submucosa of the esophagus?
dense, irregular fibroelastic connective tissue
What are the different layers of the muscularis of the esophagus?
upper 1/3 = mostly skeletal muscle
middle 1/3 = mixed
lower 1/3 = mostly smooth muscle
True or False: We see the adventitia of the esophagus until it pierces the diaphragm, after which it is serosa
True
What are the major arteries that supply the esophagus?
- thoracic branches of the aorta (superiorly)
- branches of the left gastric artery (inferiorly)
What are the major veins that drain the esophagus?
- azygous vein
- portal venous system via the left gastric veins
The __________ compresses the esophagus superiorly to some extent
larynx
What muscles are involved in “pushing food down” when swallowing?
- cricopharyngeus muscle
- the rest of the inferior pharyngeal constrictor muscle
when an out-pouching develops and food gets stuck in the weak spot just above the cricopharyngeus muscle
Zencker Diverticulum
Note: out-pouching occurs due to cricopharyngeus muscle over-tightening
What are the three stages of deglutition (swallowing)?
1) voluntary stage
2) pharyngeal stage
3) esophageal stage
Describe the voluntary stage of deglutition (swallowing)
after chewing, food is voluntarily squeezed/rolled posteriorly into the pharynx by pressure of the tongue upward and backward against the palate
Describe the pharyngeal stage of deglutition (swallowing)
- a reflex controlled by the brain stem (medulla), triggered by food in the pharynx (tactile stimulation)
- soft palate is pulled upwards (prevents food from getting into nose)
- palatopharyngeal folds pulled together, creating a sagittal slit for food to pass with ease
Describe the esophageal stage of deglutition (swallowing)
- trachea is closed (respiration inhibited temporarily), as vocal chords are brought together and larynx is raised and epiglottis covers vocal chords
- upper esophageal sphincter relaxes
- peristaltic contraction of pharynx
Where is the swallowing center? What does it do?
medulla (brain stem)
coordinates activity from vagal nuclei with other centers (e.g., inhibits respiratory center)
Where does the swallowing center receive sensory inputs from?
pharynx and esophagus
How long is the pharyngeal swallowing stage?
less than 2 seconds
Note: Therefore, only interrupts respiration for a very small amount of time
_____________ results from distension of the esophagus by retained food, or by reflux of gastric contents into the esophagus; continues until all the food has emptied into the stomach
Secondary peristalsis
Where is the lower esophageal sphincter located?
1-2 cm below diaphragm
2-5 cm above juncture with stomach
True or False: The lower esophageal sphincter (LES) relaxes ahead of the peristaltic wave to allow easy propulsion of food into the stomach and to prevent reflux
True
At rest, is the pressure high or low at the upper esophageal sphincter (UES)?
high
At rest, is the pressure high or low at the lower esophageal sphincter (LES)?
low
(so that food can pass through)
After food has passed into the stomach, is pressure high or low in at the lower esophageal sphincter (LES)?
high
What causes relaxation of the lower esophageal sphincter (LES)?
nitric oxide (NO) and VIP-secreting branches of the vagus nerve
What are some types/groups of pathologies that can occur in the esophagus?
1) dysphagic/motility diseases
2) inflammatory diseases
3) metaplastic/neoplastic diseases (future lectures)
4) vascular diseases (future lectures)
a motility/obstructive disorder whereby swallowing contractions are too powerful (high amplitude esophageal contractions), visceral pain from the esophagus is well-localized, and excess distension causes intense and brief chest pain
Nutcracker esophagus
In Nutcracker esophagus, the ___________ layer of smooth muscle contracts before the ___________ layer
outer longitudinal,
inner circular
a motility disorder of the esophagus characterized by a dysfunction of inhibitory nerves resulting in minor obstruction or chest pain
diffuse esophageal spasm
Note: this is very common
a motility disorder of the esophagus characterized by increased tone of the lower esophageal sphincter (LES) due to impaired smooth muscle relaxation (aka LES won’t relax), and aperistalsis of the esophagus
achalasia
Note: If inhibitory neurons do not release NO or VIP after swallowing, the LES won’t relax properly
__________ (primary/secondary) achalasia may be associated with diabetic autonomic neuropathy, malignancy, and infections (e.g., from tropical countries)
Secondary
____________ (primary/secondary) achalasia is idiopathic and caused by failure of distal esophageal inhibitory neurons
Primary
How does achalasia present clinically?
- dysphagia (difficulty swallowing)
- chest pain
- regurgitation
True or False: Achalasia increases mortality, especially when malignancy is involved
False
Achalasia does NOT affect mortality, UNLESS malignancy is involved
What is the treatment for achalasia?
- botox
- myotomy
Other causes of dysphagia may include iron-deficiency anemia or chronic reflex disease. How do these conditions cause dysphagia?
they can sometimes cause fibrosis or non-malignant growths that obstruct the esophagus
True or False: Worsening dysphagia and reflux symptoms need to be investigated to ensure that the patient has not developed esophageal cancer
True
an inflammatory condition of the esophagus that is usually a sign of immunosuppression involving HSV, cytomegalovirus (CMV) or fungal organisms (candidiasis = most common)
infectious esophagitis
an inflammatory condition of the esophagus which may be due to Crohn’s disease (rare), scleroderma, or eosinophilic esophagitis
autoimmune esophagitis
In eosinophilic esophagitis, there are ______ eosinophils/per high-power field
> 15
True or False: Eosinophilic esophagitis is an emerging disease, with increasing incidence (both children and adults)
True
Describe the pathophysiology of eosinophilic esophagitis
- Th2 response with an abundance of IL-4, IL-5, and IL-13 in the serum and in affected tissue
- often a history of atopic illness (e.g., asthma, eczema) during or before GI symptoms
- food intolerances/allergies = major inciting factors
What are the clinical features of eosinophilic esophagitis in children?
- nausea
- vomiting
- small for age
- weight loss (severe cases)
- heartburn/reflux (in older children)
What are the clinical features of eosinophilic esophagitis in adults?
- dysphagia (difficulty swallowing)
- food impaction
- chest pain (possible)
- heartburn that is usually resistant to PPI treatment
How is eosinophilic esophagitis diagnosed?
- endoscopy
- IgE levels elevated
What is the most frequent cause of esophagitis?
reflux esophagitis
(reflux of gastric contents into the lower esophagus)
True or False: In reflux esophagitis, the histology of the esophagus is normal (e.g., stratified squamous epithelium)
True
Note: Stratified squamous epithelium is resistant to abrasion from food but is sensitive to acid
True or False: Decreased LES tone or increased abdominal pressure can contribute to GERD
True
What are some aggravating factors for reflux esophagitis?
- alcohol and tobacco use
- obesity
- CNS depressants
- pregnancy
- hiatal hernia
- delayed gastric emptying
- increased gastric volume
What are some findings associated with reflux esophagitis?
- hyperemia (increased blood flow to esophagus)
- mild eosinophilic infiltration
- basal zone hyperplasia** exceeding 20% of total epithelial thickness
- elongation of lamina propria papillae (severe cases)
- Barrett’s esophagus* in more severe cases (patches of red, velvety mucosa; can be pre-malignant in rare cases and should be followed over time via endoscopy)
What are the clinical features of reflux esophagitis?
- dysphagia
- heartburn
- regurgitation (less frequently)
- chronic GERD may be punctuated by severe chest pain attacks (rare)
How is reflux esophagitis treated?
proton pump inhibitors or H2 histamine receptor antagonists
True or False: Severity of symptoms and disease duration in reflux esophagitis is closely related to the degree of histological damage
False
Only disease duration is closely related to degree of histological damage (severity of symptoms is not necessarily related to degree of histological damage)
Heartburn that increases in severity and is accompanied by dysphagia is a red flag for _______________
esophageal carcinoma
What are some food triggers for reflux esophagitis?
- coffee and tea
- choclate
- spicy food
- beer, wine, other forms of alcohol
- fried or greasy foods
- mint
- tomatoes or tomato-based food
- sweets and high-glycemic foods
Note: over-eating and stress can also trigger reflux
