60. Oesophagus - physio Flashcards
(20 cards)
What is the main function of the oesophagus?
The oesophagus moves food and liquids from the mouth to the stomach using coordinated muscle contractions called peristalsis.
What is peristalsis?
Peristalsis is a series of wave-like muscle contractions in the oesophagus wall that push food downward toward the stomach.
What controls peristalsis in the oesophagus?
Peristalsis is controlled by the autonomic nervous system and the myenteric (Auerbach’s) nerve plexus between the muscle layers.
What is the role of the upper oesophageal sphincter (UES)?
The UES is a ring of muscle at the top of the oesophagus that opens during swallowing to let food in, and stays closed otherwise to prevent air from entering the oesophagus.
What is the role of the lower oesophageal sphincter (LES)?
The LES is a ring of smooth muscle at the bottom of the oesophagus that stays tightly closed to prevent stomach acid from coming back up, but opens to let food into the stomach.
How does swallowing (deglutition) work?
Swallowing involves voluntary movement (in the mouth and pharynx) followed by involuntary peristalsis in the oesophagus to carry the bolus (food ball) to the stomach.
Why is oesophageal peristalsis important?
It ensures that food moves in one direction, even against gravity (like when lying down), and clears any leftover material from the oesophagus.
What prevents reflux (backflow) from the stomach into the oesophagus?
The lower oesophageal sphincter (LES) and the diaphragm muscle around the oesophagus help keep stomach acid from moving back up.
What happens if the lower oesophageal sphincter is weak or relaxed too often?
Stomach acid can flow back into the oesophagus, causing gastroesophageal reflux disease (GERD), which leads to heartburn and irritation.
How is the oesophagus protected from damage during food passage?
By mucus secretion (from glands), a tough epithelium layer, and coordinated muscle contractions that quickly move harmful substances down.
What triggers the start of swallowing?
Swallowing starts voluntarily when the tongue pushes food to the back of the mouth, triggering sensory signals that activate the swallowing reflex.
What is the swallowing reflex?
An involuntary reflex controlled by the brainstem that coordinates closing the airway and opening the oesophagus to let food pass safely.
What prevents food from entering the trachea during swallowing?
The epiglottis folds down to cover the laryngeal opening, and the vocal cords close tightly to protect the airway.
What is the normal resting pressure of the lower oesophageal sphincter (LES)?
About 10–30 mmHg, providing a barrier that prevents gastric contents from refluxing into the oesophagus.
What happens to the LES during swallowing?
The LES relaxes briefly to allow the food bolus to enter the stomach, then contracts again to maintain its barrier function.
How is oesophageal motility tested clinically?
With oesophageal manometry, where sensors measure the strength and coordination of muscle contractions and sphincter pressures.
What is the physiological role of mucus in the oesophagus?
Mucus reduces friction during food passage and protects the lining from mechanical injury and minor acid exposure.
Why does the oesophagus need both skeletal and smooth muscle?
Skeletal muscle in the upper part allows voluntary control at the start of swallowing; smooth muscle in the lower part ensures automatic transport into the stomach.
