1b// Upper GI Tract Flashcards
What are the sphincters of the oesophagus?
upper and lower
Label.
Where does the oesophagus start?
C5, trachea
Which side does the aorta lie to compared to the oesophagus?
to the left
Where does the oesophagus end?
T10, diaphragm
How is the oesophagus split into 2?
thoracic and abdominal oesophagus
What is the arterial and venous supply to the thoracic oesophagus?
arterial supply from the branches of the thoracic aorta and the inferior thyroid artery
Venous drainage into the systemic circulation occurs via branches of the azygous veins and the inferior thyroid vein.
What is the arterial and venous supply of the abdominal oesophagus?
The abdominal oesophagus is supplied by the left gastric artery (a branch of the coeliac trunk) and left inferior phrenic artery.
This part of the oesophagus has a mixed venous drainage via two routes: To the portal circulation via left gastric vein. To the systemic circulation via the azygous vein.
What are the 2 plexuses in the oesophagus?
myenteric and meissner
What are the anatomical contributions to the lower oesophageal sphincter? (4)
- 3-4 cm distal oesophagus within abdomen
- Diaphragm surrounds LOS (Leftt & Right crux)
- An intact phrenoesophageal ligament
- Angle of His
What are the stages of swallowing?
stage 0= oral phase
stage 1= pharyngeal phase
stage 2= upper oesophageal phase
stage 3= lower oesophageal phase
What happens in stage 0 of swallowing?
all in mouth
- Chewing & saliva prepare bolus
- Both oesophageal sphincters constricted
What happens in stage 1 of swallowing?
- Pharyngeal musculature guides food bolus towards oesophagus
- circular and longitudinal muscle
- Upper oesophageal sphincter opens reflexly
- LOS opened by vasovagal reflex (receptive relaxation reflex)
What happens in stage 2 of swallowing?
- Upper sphincter closes
- Superior circular muscle rings contract & inferior rings
dilate - Sequential contractions of longitudinal muscle
What happens in stage 3 of swallowing?
- Lower sphincter closes as food passes through
What determines oesophageal motility?
determined by pressure measurements (manometry)
What is the pressure roughly of peristaltic waves?
40mmHg
What is the LOS resting pressure?
roughly 20mmHg
When does LOS pressure decrease?
decreases 5mmHg during receptive relaxation (when the bolus goes down)
What mediates the decrease in pressure of the LOS?
mediated by inhibitory noncholinergic nonadrenergic (NCNA) neurones of the myenteric plexus
What does the myenteric plexus do?
motility, allows relaxation
What does Meissner’s plexus do?
helps with secretions, and blood supply to oesophagus
What is the major cause of functional disorders of the oesophagus?
absence of structure
What causes the absence of structure in the oesophagus leading to disorders? (2)
abnormal oesophageal contraction
failure of protective mechanisms for reflux