40 Questions
What is the main function of the digestive tract?
To mechanically digest food and absorb nutrients
What are the four main layers of the digestive tract wall?
Mucosa, submucosa, muscularis, and adventitia
What is the function of the mucosa in the digestive tract?
To absorb nutrients
What is the function of the submucosal nerve plexus?
To control muscle contractions
What is the main component of the oral cavity?
Mucosa, tongue, and teeth
What is the function of the digestive glands?
To chemically digest food
What is the component of the digestive tract that is responsible for storing waste products?
Large intestine
What is the function of the muscularis layer in the digestive tract?
To control muscle contractions
What is the location of the 8-12 CV in the oral cavity?
In front of the sulcus terminalis
What is the function of the taste buds?
To sense the four basic tastes
What is the shape of a taste bud?
Onion-shaped
What is the function of the microvilli in taste cells?
To increase the surface area for taste reception
What is the name of the opening at the tip of each root of a tooth?
Apical foramen
What is the main component of tooth enamel?
Hydroxyapatite crystals
What is the name of the papillae that do not contain taste buds?
Filiform papillae
What is the name of the cells that are responsible for sensing the four basic tastes?
Receptor cells
Which tissue surrounding the dentin of the root of the tooth is bone-like?
Cementum
What is the main function of the pulp in the tooth?
Provides nutrients
What is the main component of dentin?
70% hydroxyapatite
Which of the following is NOT a part of the periodontium?
Pulp
What is the function of the periodontal membrane?
Supports the tooth
What is the characteristic of the alveolar bone?
Lacks the typical lamellar pattern of adult bone
What is the characteristic of the mucosa in the esophagus?
Composed of stratified squamous epithelium and lamina propria
What is the function of the submucosa in the esophagus?
Produces mucus to lubricate and protect the mucosa
What is the main function of the epithelium in the digestive tract?
Protection, absorption, and secretion
What type of muscles are present in the muscularis mucosa?
Smooth muscles
What is the main function of the lamina propria?
Support and structure to the epithelium
What type of muscles are present in the muscularis external?
Both skeletal and smooth muscles
What is the function of the submucosa?
Protection of the underlying tissue from bacterial invasion
What is the function of the muscularis external?
Mixing and propelling of food in the digestive tract
What is the main function of the epithelium in the midpiece of the digestive tract?
Absorption and secretion of nutrients
What is the function of the plicae?
Increase the surface area of the digestive tract
What are the three sublayers of smooth muscle?
Inner oblique, middle circular, and outer longitudinal layers
What is the function of the cardiac sphincter?
To prevent backflow of food into the esophagus
What is the pH range of gastric juice?
pH 0.9-1.5
What is the function of the mucosa in the small intestine?
To isolate the epithelial cells from the lumen
How long is the jejunum segment of the small intestine?
2 meters long
What is the function of the Brunner's glands?
Not mentioned in the text
What is the function of the folds in the small intestine?
To increase the surface area
What is the function of the muscularis layer in the small intestine?
To move food through the intestine
Study Notes
Digestive Tract
- The digestive tract is an open, continuous canal from the oral cavity to the anus.
- Its functions are to mechanically digest food and absorb nutrients.
Components of Digestive Tract
- Oral cavity
- Gastrointestinal tract
- Anus
Layers of Digestive Tract
- Mucosa: embodies various functions of different tract segments.
- Epithelium: stratified squamous or simple columnar.
- Lamina propria: loose connective tissue.
- Muscularis mucosa: inner circular and outer longitudinal layer of smooth muscles.
- Submucosa: loose connective tissue containing large nerve fibers, blood vessels, and lymphoid nodules.
- Muscularis: skeletal or smooth muscles arranged in two or three layers.
- Adventitia: serous or fibrous membrane.
Tongue and Teeth
- Tongue: contains taste buds, with ~10,000 taste buds in the human mouth.
- Taste buds: onion-shaped structures containing 50-100 cells, including receptor cells, supporting cells, and basal cells.
- Teeth:
- Division: crown, neck, and root.
- Composition: enamel, dentin, cementum, and pulp.
- Pulp cavity: contains dental pulp, a loose connective tissue rich in blood vessels, lymphatics, and nerves.
- Apical foramen: opening at the tip of each root for blood vessels, lymphatics, and nerves.
Esophagus, Stomach, and Intestine
- Esophagus:
- Mucosa: nonkeratinized stratified squamous epithelium, loose connective tissue, and longitudinal arranged smooth muscles.
- Submucosa: loose connective tissue containing small mucous esophageal glands.
- Muscularis: three sublayers of smooth muscle.
- Adventitia: thin serosa.
- Stomach:
- Functions: store food, continue digestion, add acidic fluid, and begin protein digestion.
- Self-protection mechanism: muco-hydrocarbonate barrier.
- Small intestine:
- Composed of duodenum, jejunum, and ileum.
- Functions: terminal food digestion, nutrient absorption, and endocrine secretion.
- Structure: four layers, including mucosa with special features, typical submucosa, muscularis, and serosa.
Quiz on the components and functions of the digestive tract and digestive glands, including mechanical and chemical digestion.
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