1b Upper GI Tract Flashcards
Where does the oesophagus run from in terms of vertabrae?
C5-T10
What type of muscle does each third of the oesophagus have?
Upper = Skeletal
Middle = Skeletal / Smooth
Lower = Smooth
Describe the change in epithelium which when going from the top of the oesophagus to the bottom?
Non keratinizing squamous epithelium to columnar epithelium
Which bone is the upper oesophageal sphincter related to?
Hyoid bone
What is the name of the ligament that attaches the diaphragm to the oesophagus?
Phrenoesophageal ligament
What is the function of this ligament? Phrenoesophageal ligament
Allows the independent movement of the diaphragm and oesophagus during respiration and swallowing
What is the angle of His?
Acute angle created between the cardia at the entrance to the stomach and the oesophagus
What is the function of the angle of His?
Prevents reflux of duodenal bile enzymes and gastric acid from entering the oesophagus
Which part of the diaphragm surrounds the LOS?
LEFT and RIGHT Crux
How much of the distal oesophagus is within the abdomen?
3-4 cm
What happens in stage 0 (Oral phase) of swallowing?
Chewing and saliva prepare the bolus
UOS and LOS are BOTH CLOSED
What happens in stage 1 (Pharyngeal phase) of swallowing?
Pharyngeal musculature guides food bolus towards the oesophagus
UOS opens reflexly
LOS Opened by the vasovagal reflex
Which reflex causes the LOS to open during the pharyngeal phase of swallowing?
receptive relaxation reflex
What happens in stage 2 (Upper oesophageal phase) of swallowing?
Upper sphincter closes
Superior circular muscle rings contract and inferior rings dilate
Sequential contractions of longitudinal muscle
What happens in stage 3 (lower oesophageal phase) of swallowing?
Lower sphincter closes as food passes through
As the bolus passes through the oesophagus, what happens to the muscles?
Superior muscles contract
Inferior muscles dilate in order to make space for the food bolus to pass through
What is manometry and what is it used to do?
When a probe is placed into the oesophagus and used to measure the pressure inside it
What is the pressure of normal peristaltic waves
About 40 mmHg
What is the LOS resting pressure?
About 20 mmHg
What happens to the pressure inside the oesophagus during receptive relaxation?
decreases to less than 5
What is the pressure and motility of the oeseophagus mediated by?
Inhibitory noncholinergic nonadrenergic neurones of myenteric plexus
What is the Receptive Relaxation of the LOS mediated by?
Inhibitory non-cholinergic noradrenergic (NCNA) neurons of myenteric plexus
They prevent constriction and so they induce relaxation
What is the most common reason for a functional disorder of the oesophagus?
Absence of a stricture
In the absence of the stricture, what is the most common cause of functional disorders of the oesophagus?
- Abnormal oesophageal contraction
- Failure of protective mechanisms for GORD
What is dysphagia?
Difficulty in swallowing
What is odynaphagia?
pain on swallowing
What is regurgitation?
Refers to the return of oesophageal contents from above an obstruction
What is meant by reflux?
The passive return of gastroduodenal contents to the mouth
What condition is caused by hypermobility?
Achalasia
What causes achalasia?
Due to loss of ganglion cells in Aurebach’s myenteric plexus in LOS wall, leading to DECREASED ACTIVITY inhibitory NCNA neurones - therefore more mobility
What is seen on images of the oesophagus in achalasia?
Birds beak = tapering of the distal oesophagus
Which conditions could cause oesophageal motor abnormalities similar to PRIMARY ACHALASIA?
Chagas’ disease
PROTOZOA INFECTION
Amyloid / Sarcoma / Eosinophillic Oesophagitis
Describe the onset of achalasia?
Insidious onset = symptoms for years prior to seeking help, without treatment can lead to progressive oesophageal dilation of oesophagus
What happens to the resting pressure of the LOS in achalasia?
Increased resting pressure
What happens to the receptive relaxation phase in achalasia?
Sets in too late, and is to weak
during the reflex phase the pressure in the LOS is markedly higher than stomach
How does achalasia cause dilation of the oesophagus?
Swallowed food collects in the oesophagus causing increased pressure throughout with dilation of the eosophagus
What is PD?
Pneumatic dilation
How is PD a treatment for achalasia?
Dilator into the LOS, inflated and causes the LOS to expand
PD weakens the LOS by circumferential stretching and tearing of the muscle fibres
LOS is too tight in Achalasia, therefore PD is needed to relax it to allow food to pass through the oesophagus
What happens to the LOS in achalasia?
TOO TIGHT
NCNA neurones cause the LOS to relax
Therefore if they are decreased activity in achalasia, the LOS becomes very tight
What is Heller’s myotomy?
A continuous myotomy performed for 6cm on the oesophagus and 3cm into the stomach
What is a dor fundoplication?
Anterior fundus folded over oesophagus and sutured to right side of myotomy
What is a dor fundoplication used to do?
Anti-reflux
What are the risks of surgery on the LOS?
Perforation
division of vagus nerve
splenic injury
Which condition causes hypomobility?
Scleroderma
What does hypomobility lead to?
Leads to atrophy of smooth muscle of oesophagus, such that peristalsis in the distal portion ultimately ceases altogether
What happens to the resting pressure of the LOS in scleroderma?
Decreased
What is GORD that develops as a result of scleroderma often associated with?
CREST Syndrome
What is the treatment for Scleroderma?
- exclude organic obstruction
- Improve force of peristalsis with prokinetics (cisapride)
What is corkscrew oesophagus?
When there is disordered coordination resulting in diffuce oesophageal spasms
What are the symptoms of corkscrew oesophagus?
dysphagia and chest pain
What happens to the circular muscle in the oesophagus in corkscrew oesophagus?
Marked hypertrophy of the muscle
What is the treatment of corkscrew oesophagus?
May respond to forceful PD of cardia
What are the three locations in which oesophageal perforations due to anatomical constriction may occur?
Cricopharyngeal
Aortic and bronchial
Diaphragmatic and sphincter
What might cause pathological narrowing of the oesophagus?
Cancer, foreign body or physiological dysfunction
Whats the most common cause of oesophageal perforations?
Iatrogenic - OGD
What does an OGD commonly perforate?
Killian’s triangle
What causes Boerhaave’s perforation?
Sudden increase in intra-oesophageal pressure with negative intra thoracic pressure
What activity can cause Boerhaave’s perforation?
Vomiting against a closed glottis
Where does Boerhaave’s perforation occur?
Left posterolateral aspect of the distal oesophagus
Why is children swallowing disc batteries a large problem?
Causes electrical burns if embedded into the mucosa, become logged in the oesophagus and erodes, creating a whole in the oesophagus
What signs might suggest trauma causing perforation?
Dysphagia
Blood in the Saliva
Haematemesis
Surgical emphysema
What imaging is done to identify a oesophageal perforation?
CXR
CT
Swallow
OGD
See oesophageal contents leak into the mediastinum on the scan
What are the most common symptoms of oesophageal perforation?
Chest pain
Fever
Dysphagia
Emphysema
What is the initial management of oesophageal perforation?
Initial Management = Nil By Mouth, IV Fluids, Broad spectrum A/Bs and Antifungal
Why are both a/b’s and antifungals needed to treat oesophageal perforation?
Due to the high abundance of fungi in the oesophagus therefore both are needed
What is the definitive management of Oesophageal perforation?
covered metal stent
Why is the LOS usually closed?
As a barrier against reflux of harmful gastric juice (pepsin and HCl)
What happens to the LOS when pressure is high?
Reflux is inhibited
What happens to raise LOS pressure?
ACh
α-adrenergic agonists
hormones
protein high food
Histamine
high intra-abdominal pressure
PGF2α- Prostaglandin F2alpha
What happens when the pressure of LOS is low?
Reflux is promoted
What lowers the LOS pressure?
VIP (Vasoactive intestinal polypeptide)
β-adrenergic agonists
hormones
Dopamine
NO
PGI2 (Prostaglandin I2)
PGE2 (Prostaglandin E2)
chocolate
acid gastric juice
Fat
Smoking
What are the three mechanisms which protect following reflux?
- Volume clearange - oesophageal peristalsis reflex
- pH clearance - saliva
- Epitheloium has barrier properties
Describe what happens if the protective mechanisms against reflux do not work?
Reflux oesophagitis, leads to epithelial metaplasia
This leads to carcinoma
Why might the protective mechanisms against reflux fail?
- Reduced sphincter pressure
- Transient sphincter opening
- Abnormal peristalsis (reduce volume clearance)
- Reduced saliva production [in sleep xerostomia] (reduced pH clearance)
- Reduced buffering capacity of saliva [e.g. smoking] (reduced pH clearance)
- hiatus hernia
- Defective mucosal protective mechanism [e.g. alcohol]
all cause reflux oesophagitis then epithelial metaplasia then carcinoma
What is a sliding hiatus hernia?
When a portion of the stomach slides up through the diaphragmatic hiatus
What is a rolling hernia?
When the herniated portion of the stomach pushed through the diaphragmatic hiatus but next to the oesophagus
What is the purpose of doing a OGD for GORD?
To exclude cancer
Oesophagitis, peptic stricture and Barrett’s
What are the treatments for GORD / hernia?
Lifestyle changes
PPI’s - proton pump inhibitor
Dilation of peptic strictures
Laparoscopic Nissen’s fundoplication
What is Nissen’s fundoplication?
When a portion of the stomach (fundus) is taken and wrapped around the oesophagus to help prevent reflux
What is the funtion of the stomach?
Break food into smaller pieces using acid and pepsin
Holds food, releasing it in controlled steady rate into the duodenum
Kills parasites and certain bacteria - using low pH
What does the cardia and pyloric region of the stomach secrete?
Mucus only
What does the body and fundus of the stomach secrete?
Mucus, HCl and pepsingogen
What does the antrum of the stomach secrete?
Gastrin
What does gastrin do?
Stimulates acid production, works via a negative feedback loop
What is the most common cause of gastritis?
Helicobacter pylori
What is the treatment for non-erosive, chronic active gastritis?
Triple treatment = amoxicillin, clarithromycin and pantoprazole for 7-14/7
Gastritis affecting the fundus?
Atrophic gastritis
Gastritis affecting the antrum?
Non-erosive, chronic active gastritis
- increased GASTRIN
- increased acid secretion
- Chronic gastric / duodenal ulcer
- Reactive gastritis
What does atrophic gastritis lead to?
Parietal cell atrophy, reduced acid and IF secretion leading to pernicious anaemia
Which gastritis forms acute ulcers?
Erosive and haemorrhagic gastritis
What is the neural stimulant of gastric acid secretion?
ACh - post ganglionic transmitter of vagal parasympathetic fibres
What is the endocrine stimulant of gastric acid secretion?
Gastrin from the G cells of the antrum
What is the paracrine stimulant for gastric acid secretion?
Histamine (ECL [Enterochromaffin-like] cells and mast cells of gastric wall)
What are the inhibitory factors of gastric acid secretion?
Secretin
Somatostatin
PGs (E2 and I2), TGF-alpha and adenosine
What generates bicarb for mucosal protection?
Prostaglandins - also inhibited by NSAID’s, so when taking them, gastric perforation is a complication
Describe the mucosal protection against ulcers?
- Mucus film
- HCO3- secretion
- Epithelial barrier
- Mucosal blood perfusion
How does migration work as a mechanism for epithelial repair and wound healing?
Adjacent epithelial cells flatten to close the gap via sidewards migration along the basement membrane
How is the gap in the epithelium of the stomach closed by cell growth?
Stimulated by EGF, TGF-alpha, IGF-1 and GRP and gastrin
How does acute wound healing occur?
BM destroyed-
attraction of leukocytes & macrophages; phagocytosis of necrotic cells; angiogenesis; regeneration of ECM after repair of BM
epithelial closure by restitution & cell division
Describe how ulcer formation occurs?
- Helicobacter pylori
- Increased gastric acid secretion
- Decreased bicarb secretion
- Reduced cell formation
- Reduced cell perfusion = less mucosal protection so barrier function disrupted
What is the most common outcome of H. pylori infection?
Chronic gastritis
What is the medical treatment for stomach ulcers?
PPI or H2 blocker
Triple Rx (Amoxicillin, clarithromycin and pantoprazole)
What is zollinger-Ellison syndrome?
Antral G-cell hyperplasia or gastrinoma
What are the surgical indications for the treatment of stomach ulcers?
Intractability (after medical therapy)
Relative: continuous requirement of steroid therapy/NSAIDs
Complications:
Haemorrhage
Obstruction
Perforation
If an ulcer has not healed in 12 weeks, what should be done?
Change medication and observe for another 12 weeks
Check serum gastrin (antral G cell hyperplasia or gastrinoma [Zollinger-Ellison syndrome - too much gastric acid])
How do NSAIDs and Smoking lead to ulcer formation?
Decrease prostaglandin synthesis → Increased H+ & Pepsinogen secretion → Increased chemical aggresion
Which prostaglandins are affected by smoking?
Decreased PGI2
Increased PGE2
Chronic infection with the parasite Trypanosoma cruzi can cause an oesophageal motor abnormality similar to which commoner functional disorder?
Achalasia