Physiological structure of oesophagus and stomach

1. Gastro Intestinal Tract –Part II
Oesophagus
Dr. Radhakrishna G Pillai
Department of Life Sciences
University of Calicut

2. Oesophagus
• The oesophagus (gullet) is around 25cm in length
• Connects the mouth to the stomach via the
pharynx
• The oesophagus does not produce digestive
enzymes
• It secrete large amounts of mucus that act as a
lubricant, ensuring the smooth transit of the food
bolus

3. Oesophagus
It has cervical,
thoracic, and
abdominal parts

4. Sphincters
• After having been swallowed, the food bolus passes
through the upper oesophageal sphincter (UOS)
• Stretch the oesophageal wall and triggering peristalsis
• The UOS closes rapidly and tightly to prevent
regurgitation of food into the pharynx and mouth
• The transit time of food through the oesophagus
varies according to factors such as age, health and the
nature of the food consumed, but is typically 6-15
seconds

5. Lower oesophageal sphincter
• Once the food bolus reaches the lower portion of the
oesophagus, the lower oesophageal sphincter (LOS)
dilates
• Allow it to pass into the stomach
• The LOS (also called the cardiac sphincter due to its
proximity to the heart) closes as soon as the bolus
enters the superior portion of the stomach
• Prevent regurgitation of highly acidic gastric juices
into the oesophagus
• A variety of conditions – for example, hiatus hernia –
can lead to poor closure of the LOS and result in acid
reflux

6. Oesophagus-wall
• Wall of oesophagus is composed of four
layers;
– the mucosa
–Submucosa
–muscularis and
–adventitia
• Unlike the remainder of the GI tract, the
esophagus has no serosa

7. Wall of Oesophagus

8. Muscle
distribution
in
Oesophagus

9. Sphincters

10. Peristalsis

11. Innervation
Parasympathetic and sympathetic
innervation of the esophagus
(Source: Netter medical illustration
https://www.nature.com/gimo/contents/pt1/fu
ll/gimo6.html accessed n 01-04-2020