Lecture 4: Esophagus Pathophysiology Flashcards
What is the job description to esophagus?
- To propel swallowed food into stomach
- Prevent gastroesophageal reflux
- clear refluxed material back into stomach
- Vomiting and belching
Where is esophagus located?
- originates in neck
- ends in stomach
- passes through RIGHT CRUS of diaphragm
What are the two types of muscles located in the esophagus?
Proximal portion is STRIATED (circular)
Distal portion is LONGITUDINAL (smooth)
What are types of diseases that the striated musscle portion of the esophagus can be affected by?
- Polymyositis
2. myasthenia gravis
What are the types of disease that the smooth muscle portion of the esophagus can be affected by?
- Scleroderma
2. Achalasia
What are the key characteristics of the upper esophageal sphincter?
- Striated muscle
- separates pharynx from esophagus
- composed of 3 adjacent muscles
i. inferior pharyngeal constrictor
ii. cricopharyngeus
iii. Cervical esophagus - prevents AIR ENTRY into GI tract and reflux of gastric contents into pharynx
- allows belching and vomiting; allows food into esophagus
What are the key characteristics of the gastroesophageal junction?
- comprised of two sphincters
i. lower esophageal sphincter
ii. Diaphragm - Anchored in place by phreno-esophageal ligament
What is achalasia?
When you can’t relax your lower esophageal sphincter when swallowing
Is there a serosal layer in the esophagus?
NO SEROSAL LAYER
Where do lymphatics of the esophagus come up to?
Comes up to the epithelium
Cancer of esophagus is rapidly spreading disease because of how close lymphatics are
When is the process of swallowing voluntary? Involuntary?
Voluntary = pharynx
Involuntary = esophagus
Act of swallowing activates esophageal activity
What innervates the skeletal muscle?
Nucleus ambiguous
Contact is DIRECT
What innervates the smooth muscle of the esophagus?
DMX (dorsal motor nucleus of X)
Has to go through myenteric plexus
What are the characteristics of vagal dorsal motor nucleus innervation to striated muscles of esophagus?
- Caudal inhibitory pathways
- NO is neurotransmitter
- Rostral excitatory pathways
- aCH is excitatory
What does swallowing do in terms of innervation?
Swallowing activates INHIBITORY PATHWAYS FIRST (to relax shit)
Simultaneous inhibition of entire esophagus (distal > upper)
Followed by sequential activation of excitatory pathways
What is the cholinergic gradient in the SMOOTH muscle portion of esophagus?
Cholinergic (excitatory) is marked proximally
Noncholinergic (inhibitory) is distal
This leads to peristalsis
What does the lower esophageal sphincter do at rest?
Closed tonically
Pressure falls within 1.5-2.5 seconds of swallowing
Remains low for 5-6 seconds
What are the three mechanisms involved in the regulation of basal LES tone?
- swallow induced relaxation
- cessation of tonic neural excitation
- NANC inhibitory neurons (NO), inhibition of cholinergic neuron
What does NANC stand for?
Nitrergic modulation of cholinergic
What is dysphagia?
PERCEPTION that there is an impediment to normal passage of swallowed material
What is odynophagia?
Sensation of pain on swallowing
What is globus?
Feels as if a ball is lodged in lower part of esophagus
What are esophageal symptoms?
- regurgitation
Effortless return of gastric contents into chest or mouth - chest pain
- heartburn
Burning feeling rising from stomach or lower chest up toward the neck
What is the key characteristic of achalasia?
Bird’s beak (the white shit is food)
When lower esophageal sphincter wont relax
How do you treat achalasia?
Pneumatic dilation
Medications are NOT effective
Laproscopic heller
What is laproscopic heller?
When you destroy muscles of the gastroesophageal junction
What is the pathogenesis of achalasia?
- decrease in MYENTERIC neurons in distal esophagus
2. especially decrease in inhibitory NO releasing neurons
How do you diagnose achalasia?
Endoscopic
Manometric
Radiographic
What is the etiology of myenteric plexus?
- autoimmune
- viral
- neurodegenerative
Equal prevalence in men and women
What does pseudochalasia look like?
Very freaking rare Due to i. primary cancer of Gastro esophageal junction ii. gastric band iii. secondary cancer
What is GERD?
GastroESOPHAGEAL reflux disease
ACID REFLUX
A condition that develops when the reflux of stomach contents causes troublesome symptoms and/or complications
2 heartburn episodes/week
If a patient presents with heartburn, what should you think of first?
GERD
What is the pathogenesis of GERD?
- decreasing salivation
- impaired tissue resistance
- impaired esophageal clearance
- Decreased LES resting tone
- Delayed gastric emptying
- Hiatal hernia
Offense = acid (too much acid because less gastric emptying)
Defense is the impaired esophageal clearance
What does obesity do to increase risk for GERD?
Abdomen is positive pressure
Chest is negative pressure
If you have more abdomen positive due to OBESITY, then you are going to
1. increase the separation between the diaphragm and the lower esophageal sphincter
2. leads to hiatal hernia
3. The more positive pressure of the abdomen means the lower diaphragm is in the stomach so the less it is able to keep acid into the esophagus
What is the treatment for GERD?
- lifestyle measures
- antacids
- antisecretory therapy
- H2 blockers
- proton pump inhibitors
- antireflux surgery
What is Barrett’s esophagus?
Intestinal METAPLASIA
Leads to adenocarcinoma of esophagus
What are the risk factors for Barrett’s esophagus?
Disease of males (4:1) Caucasian Increasing age Frequent long standing reflux symptoms Smoking Obesity (central adiposity)
What happens in Barret’s esophagus?
Squamous cells goes to columnar cells
Unclear how this happens
Transcription factors may promote columnar differentiation induced b acid/bile injury
What is the treatment for early Barrett’s esophagus?
You can use endoscopy to take that away
This is because this is usually on the surface
What is Eosinophilic Esophagitis?
Eosinophilic infiltration into the epithelium
Clinicopathologic disorder
Esophageal or upper GI symptoms
Absence of GERD (failure to respond to PPI) and normal pH monitoring
Males are at risk
What is the pathogenesis of Eosinophilic Esophagitis?
Cause unclear ALLERGIC disease of the esophagus Activates TH2, TH2 immune response More IL-4, 5, 13 Etiology unknown Fibrosis of the esophagus
What are the symptoms of eosinophilic esophagitis?
Dysphagia Food impaction Heartburn/regurgitation Chest pain Abdominal pain Odynophagia Perelman medicine guy lol
What is Eotaxin 3?
It is activated by TH2 cell by the allergies
Leads to mast cell
Inflammation to fibrosis
What are the key characteristics of scleroderma?
Fibrosis of the esophagus
What is TLESR?
Transient Lower esophageal sphincter relaxation
Easier to relax the more you are obese?
Leads to GERD
