M10S3: Esophagus And Stomach

Question 1

Esophagus: Gross anatomy

Answer 1

-following oral cavity
-muscular tube measuring 25 cm in length
-extends from pharynx to stomach

Question 2

Esophagus: histology

Answer 2

-characterized by four layers

Mucosa
-stratified squamous epithelium protects the esophagus from friction as food travels from oral cavity to stomach

Submucosa
-contains mucus-secreting glands
-mucus secreted is transported through duct to be deposited into lumen of esophagus
-mucus will lubricate tract to allow food to pass through more easily

Muscularis externa
-consists of smooth muscle typically BUT in esophagus, includes smooth and skeletal muscle
-upper 1/3 = only skeletal muscle
-middle 1/3 = mixed skeletal and smooth muscle fibres
-lower 1/3 = entirely smooth muscle

Serosa/adventitia
- adventitia covers majority of esophagus
-composed of loose connective tissue

*refer to goodnotes

Question 3

Regions of stomach

Answer 3

-J shaped organ
-3 regions: fundus, body, antrum
-antrum continuous with first aspect of small intestine, known as duodenum
*refer to goodnotes

Question 4

Stomach: Gross anatomy

Answer 4

-shape of stomach gives rise to lesser and greater curvatures
-greater omentum is structure that hangs off greater curvature of stomach, apronlike structure that covers and protects the abdominal viscera
*refer to goodnotes

Question 5

Stomach: histology

Answer 5

-histology reflects the function of the organ, therefore different from that of the esophagus

Mucosa
-folded into ridges and folds called rugae
-rugae are non-permanent folds and allow stomach to expand following ingestion of food or liquid
-epithelium is simple columnar and inward folds extend down into lamina propria to form gastric glands
-epithelium secretes mucus, which helps protect the stomach from acids secreted by gastric glands
-acids facilitate the chemical digestion of food

Submucosa
-contains blood vessels, lymphatics, glands, and nerve plexuses which supply stomach tissues with oxygen and control contraction of musculature

Muscularis externa
-has three layers of smooth muscles arranged in different directions
1. An outer longitudinal
2. Middle circular
3. Inner oblique layer

Serosa/adventitia
-stomach covered with serosa
*refer to goodnotes

Question 6

Why does the stomach have three layers of muscles and esophagus has 2

Answer 6

-stomach needs to churn food during digestion and push to small intestines so require more muscular power