Digestive System Flashcards
What does the digestive system include?
The digestive system includes the gastrointestinal (GI) tract and several accessory organs.
What organs are part of the GI tract?
The GI tract includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
How are glands that release substances into the GI tract classified?
Glands that release substances into the GI tract are classified as exocrine glands because the GI tract is continuous with the external environment.
What are the accessory organs that assist in the digestion of nutrients?
The pancreas, liver, and gallbladder produce and store secretions.
Digestion
the breaking down of ingested food (mechanical digestion vs. chemical digestion)
Absorption
the entry of nutrients into the cells lining the GI tract en route to the blood or lymph
Defecation
the elimination of wastes and indigestible substances
What are the four layers of tissue that surround the lumen of the GI tract from deep to superficial?
The four layers are mucosa, submucosa, muscularis, and serosa.
What are the primary functions of the gastrointestinal (GI) tract?
The primary functions are ingestion, digestion, absorption of nutrients, and elimination of waste products.
What is the innermost layer of the GI tract called?
The innermost layer is called the mucosa.
What does the epithelial tissue layer of the mucosa contain?
The epithelial tissue layer contains both endocrine glands, which secrete hormones into the blood, and exocrine glands, which secrete substances into the lumen of the tract.
What is the function of the smooth muscle layer in the mucosa?
The smooth muscle layer creates folds in the inner lining of the stomach and small intestine, increasing the surface area available for digestion and absorption of nutrients.
What does the connective tissue layer of the mucosa contain?
The connective tissue layer contains blood vessels and lymphatic vessels that collect absorbed nutrients.
What is located superficial to the mucosa in the GI tract?
The submucosa is located superficial to the mucosa.
What is the composition of the submucosa?
The submucosa contains connective tissue intermixed with blood vessels, lymphatic vessels, and a plexus of neurons that belong to the enteric nervous system.
What is the function of the neurons found in the submucosa?
Neurons in the submucosa coordinate various functions of the GI tract.
What is the role of the submucosa?
The submucosa is a mass of connective tissue that binds the mucosa to the muscularis. It also contains blood vessels and lymphatic vessels that transport nutrients away from the GI tract.
What is located superficial to the submucosa in the GI tract?
The muscularis is located superficial to the submucosa.
What types of muscles comprise the muscularis in different parts of the GI tract?
The muscularis contains skeletal muscle in the initial portion of the GI tract (such as the mouth, pharynx, and upper esophagus) and smooth muscle in the rest of the GI tract.
How is skeletal muscle innervated and controlled?
Skeletal muscle is innervated by the somatic nervous system and under voluntary control.
How is smooth muscle innervated and controlled?
Smooth muscle is innervated by the autonomic nervous system and under involuntary control.
What are the functions of the muscles in the muscularis?
The muscles in the muscularis assist in the mechanical digestion of food (motility) and the movement of food along the GI tract (peristalsis).
What is the most superficial layer that provides support to the GI tract?
The serosa is the most superficial layer supporting the GI tract.
What is the function of the serosa?
The serosa contributes to the peritoneum, which holds and suspends portions of the GI tract within the abdominal cavity to prevent them from falling to the floor.
What is the mesentery?
The mesentery is a portion of the peritoneum that suspends the small intestine.
What do the mesenteric arteries and veins supply?
The mesenteric arteries and veins collectively supply blood to the small and large intestines.
Organs of the GI Tract:
mouth, pharynx, esophagus, stomach, small intestine, large intestine
Gi tract is responsible for …
Digestion and absorption of food.
What assists in the mechanical digestion of food within the oral cavity?
Both the teeth and tongue assist in the mechanical digestion of food.
What is the function of taste buds in the tongue?
Taste buds are sensory receptors that provide taste sensations and transmit signals to the brain via the facial nerve (CN VII) and glossopharyngeal nerve (CN IX).
What additional function does the tongue have related to digestion?
Once activated, the tongue secretes an enzyme that digests lipids in the stomach’s acidic environment.
Which cranial nerves transmit sensory signals from taste buds to the brain?
The facial nerve (CN VII) and glossopharyngeal nerve (CN IX) transmit sensory signals from taste buds to the brain.
What is the function of the palate?
The palate separates the oral and nasal cavities.
What is the hard palate composed of?
The hard palate is composed of portions of the maxilla and palatine bones.
What is the soft palate composed of?
The soft palate is composed of skeletal muscle.
What is the function of the soft palate during swallowing?
During swallowing, the soft palate moves up to cover the posterior opening to the nasal cavity, preventing food from entering it.
What is the uvula, and what is its function?
The uvula is a muscular process hanging off the soft palate’s posterior border. The soft palate and uvula are pulled superiorly to prevent food from entering the nasal cavity during swallowing.
What do salivary glands secrete into the oral cavity?
Salivary glands secrete saliva; a mixture of water, ions, and a digestive enzyme that digests carbohydrates.
What type of control are salivary glands under?
Salivary glands are under autonomic control.
What types of innervation do salivary glands receive?
Salivary glands receive sympathetic innervation from periarticular nerves and parasympathetic innervation from the facial nerve (CN VII) and glossopharyngeal nerve (CN IX).
What are the functions of saliva?
Saliva’s functions include keeping the mucous membranes of the mouth, pharynx, and esophagus moist and assisting in the chemical digestion of carbohydrates.
What is the role of the facial nerve (CN VII) and glossopharyngeal nerve (CN IX) in innervating salivary glands?
The facial nerve (CN VII) and glossopharyngeal nerve (CN IX) provide unique sensory innervation related to taste and parasympathetic motor innervation to the salivary glands.
How is the pharynx divided into sections?
The pharynx is divided into three sections: the nasal pharynx, oral pharynx, and laryngeal pharynx.
What are the respiratory and digestive functions of the oropharynx and laryngopharynx?
The oropharynx and laryngopharynx serve as the common passageway for incoming and outgoing air and incoming food, giving them both respiratory and digestive functions.