Anatomy & Physiology Flashcards
What is the esophagus
- The third organ of digestion after the mouth and the pharynx
- Serves as the channel for food from the mouth to the stomach
- Located posterior to the trachea and larynx
- Goes through the diaphragmatic hiatus to reach the stomach
What is the primary function of the esophagus
The conduction of food from the pharynx to the stomach; accomplished by peristalsis
What is peristalsis
A distally progressive band of circular muscle contractions
When is primary peristalsis initiated in the esophagus
By swallowing
Where and how does secondary peristalsis begin
- Begins in the pharynx, below the hypopharynx
- It begins without antecedent swallowing movement
- It’s elicited by esophageal distention and moves distally at 3-5cm per second
How fast does food move through the esophagus
3-5cm per second
What nerves control peristalsis
Vagal reflexes
How long is the tubular structure of the esophagus and what is the diameter
9-10 inches long (25 cm)
1 inch wide (2.5 cm)
Where does the structure of the esophagus begin
Just below the cricoid
What muscles make up the esophagus
The upper 5% of the esophagus is striated muscle
The transition zone of the esophagus is 30-40% striated muscle
The lower 50-60% of the esophagus is smooth muscle
How many layers does the esophagus have
3
What are the three layers of the esophagus
- Mucosa layer
- Submucosa layer
- Muscularis layer
What layer does the esophagus lack that the rest of the GI tract has
The serosa layer
What makes up the mucosa layer of the esophagus
- It’s covered with squamous epithelium
- Lamina propria
- Muscularis mucosa
What is the lamina propria that is in the mucosa layer of the esophagus
A thin layer of fibrous tissue that lies immediately beneath the epithelium
What is the muscularis mucosa that is in the mucosa layer of the esophagus
A thin band of smooth muscle that separates the lamina propria from the underlying submucosa
What is in the submucosa layer of the esophagus (the middle layer)
Connective tissue
Blood vessels
Nerve fibers
What is the muscularis layer of the esophagus
Outermost layer of the esophagus
Inner layer of circular muscle responsible for squeezing the esophagus
Outer layer of longitudinal muscles that contracts to shorten the esophagus
Auerbach’s plexus (myenteric plexus)
What is Auerbach’s plexus (myenteric plexus) located in the muscularis layer of the esophagus
Sympathetic nerve fibers located between the longitudinal and circular muscles
Where are the mucus glands located in the esophagus
They line the upper and lower end of the esophagus for lubrication
What are the two sphincters located in the esophagus
Upper esophageal sphincter (UES)
Lower esophageal sphincter (LES)
What is another name for the upper esophageal sphincter
The hypopharyngeal sphincter
What muscles make up the upper esophageal sphincter
Striated muscle
Cricopharyngeal muscle
Where is the upper esophageal sphincter located
Between the pharynx and the beginning of the esophagus, separating the pharynx from the esophagus
It’s anterior border is the cricoid cartilage