10 Questions
The muscularis mucosae forms two ______ layers.
layers
The submucosa may contain ______ in considerable amounts.
fat
The outer longitudinal muscle layer forms three ______ strands, the taenia coli.
flattened
Salivary glands secrete ______ that contains enzymes to initiate breakdown of carbohydrates.
saliva
The liver secretes ______ into the small intestine via the bile duct.
bile
The bile produced by the liver ______ fat.
emulsifies
The pancreas secretes an isosmotic fluid containing ______ ions that helps buffer the acid concentration chyme.
bicarbonate
The ______ forms small pouches filled with fatty tissue along the large intestine.
adventitia
The accessory organs of the digestive system include the ______ glands, liver, gallbladder, and pancreas.
salivary
The pancreas secretes an isosmotic fluid containing ______, which helps buffer the acid concentration chyme.
bicarbonate ions
Study Notes
Layers of the Gastrointestinal Tract
- Mucosa: consists of mucous epithelium, lamina propria (loose CT), and muscularis mucosae (thin layer of smooth muscle)
- Submucosa: composed of thick layer of loose CT, nerves (plexus), parasympathetic NS, blood vessels, and small glands
- Muscularis: consists of circular smooth muscle and longitudinal muscle
- Serosa/Adventitia: smooth epithelial layer
Esophagus
- Mucosa: Stratified squamous epithelium
- Muscularis: Skeletal muscle (2 layers; top 1/3) and smooth muscle (2 layers; bottom 1/3)
- Adventitia: present
Stomach
- Mucosa: Simple columnar epithelium with gastric pits
- Muscularis: Smooth muscle (3 layers)
- Serosa: present
- Gastric pits: contain exocrine cells that secrete digestive enzymes and hydrochloric acid
- Mucous cells: secrete mucus to protect the stomach from its own digestive secretions
Small Intestine
- Divided into duodenum (25-30 cm), jejunum (about first two-fifths of the rest), and ileum
- Mucosa: Simple columnar epithelium with villi (sing) and microvilli
- Muscularis: Smooth muscle (2 layers)
- Serosa: present
Large Intestine
- Constitutes the terminal part of the digestive system
- Divided into three main sections: cecum (including the appendix), colon, and rectum with the anal canal
- Primary function: re-absorption of water and inorganic salts
- Mucosa: Simple columnar epithelium with tons of Goblet cells
- Muscularis: Smooth muscle (2 layers)
- Serosa: present with pouches (appendices epiploicae) filled with fatty tissue
Accessory Organs of the Digestive System
- Salivary glands: secrete saliva with enzymes that initiate breakdown of carbohydrates
- Liver: secretes bile into the small intestine via the bile duct
- Gallbladder: stores and concentrates bile, introducing it into the small intestine
- Pancreas: secretes isosmotic fluid containing bicarbonate ions and several enzymes, including trypsin, which helps buffer acid concentration chyme
This quiz covers the distinguishing characteristics of the four layers of the GI tract, including the esophagus and stomach. It covers the mucosa, muscularis, and adventitia layers, as well as the types of epithelium and muscle found in each.
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