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60 Cards in this Set
- Front
- Back
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Name the four layers of the digestive tract from superficial to deep.
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The four layers of the digestive tract from superficial to deep are the mucosa (adjacent to the lumen), submucosa, muscularis externa, and serosa.
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What is the importance of the mesenteries?
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The mesenteries-sheets consisting of two layers of serous membrane separated by loose connective tissue- support and stabilize the organs in the abdominal cavity and provide a route for the passage of associated blood vessels, nerves, and lymphatic vessels.
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Compare the submucosal plexus with the myenteric plexus.
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The submucosal plexus is a nerve network that contains sensory neurons, parasympathetic ganglionic neurons, and sympathetic postganglionic fibers that innervate the mucosa and submucosa. The deeper myenteric plexus is a network of parasympathetic neurons, interneurons, and sympathetic postganglionic fibers that lies between the circular and longitudinal muscle fibers.
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Describe the orientation of the smooth muscle fibers in the muscularis externa of the digestive tract.
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Smooth muscle fibers in either the circular of longitudinal layers of the muscularis externa lie parallel to each other. In a longitudinal section of the digestive tract, the fibers of the superficial circular layer appear as little round balls, whereas the fibers of the deeper longitudinal layer of spindle-shaped.
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Identify the structural characteristics of smooth muscle fibers.
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Smooth muscle fibers are spindle shaped; lack T tubules, myofibrils, and sarcomeres; and the sarcoplasmic reticulum forms a loose network throughout the sarcoplasm. Because the tissue lacks sarcomeres, it is nonstriated. Additionally, the thin filaments are anchored to dense bodies.
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Why can smooth muscle contract over a wider range of resting lengths than skeletal muscle?
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Smooth muscle can contract over a wider range of resting lengths compared to skeletal muscle because of the looser organization of actin and myosin filaments in smooth muscle.
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Describe enteroendocrine cells.
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Enteroendocrine cells are endocrine cells that are scattered among the epithelial cells lining the digestive tract and that secrete hormones important to digestion.
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Cite the major mechanisms that regulate and control digestive activities.
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The major mechanisms that regulate and control digestive activities are local factors (stimuli for digestive activities, such as changes in pH or distortion of the intestinal lumen), neural mechanisms (myenteric reflexes), and hormonal mechanisms (involving neuroendocrine cells).
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Which is more efficient in propelling intestinal contents along the digestive tract: peristalsis or segmentation? Why?
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The waves of contractions that constitute peristalsis are more efficient in propelling intestinal contents along the digestive tract than segmentation, which is basically a churning action that mixes intestinal contents with digestive fluids.
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Name the structure that forms the roof of the mouth.
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The hard palate forms the roof of the mouth; the hard palate is supported by bone and the soft palate is composed of muscle with no bony support.
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Describe the location of the fauces.
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The fauces is the arched opening between the oral cavity and oropharynx.
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The oral cavity is lined by which type of epithelium?
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The oral cavity is lined by stratified squamous epithelium, which provides protection against friction and abrasion.
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Name the four types of teeth and the three main parts of a typical tooth.
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The four types of teeth are incisors, cuspids (canines), bicuspids (premolars), and molars; a typical tooth has a crown, neck, and root.
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What is the name sometimes given to the third set of molars?
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The third set of molars is sometimes called the wisdom teeth.
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Differentiate between the primary dentition and the secondary dentition.
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The primary dentition is typically composed of 20 deciduous teeth (primary teeth, milk teeth, or baby teeth), which are temporary and the first teeth to appear in children; the secondary dentition is typically composed of 32 permanent teeth that appear subsequent to the primary dentition.
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Describe the structural and function of the pharynx.
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The pharynx is an anatomical space that serves as a common passageway in the digestive and respiratory tracts; in its digestive function, it receives a food bolus function, it receives a food bolus or liquids and passes them to the esophagus as part of the swallowing process.
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Name the structure connecting the pharynx to the stomach.
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The esophagus is the structure connecting the pharynx to the stomach.
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Describe the major event in each of the three phases of swallowing.
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During the buccal phase, food is formed into a bolus; during the pharyngeal phase, the bolus contacts the palatal arches, and moves into the esophagus; during the esophageal phase, swallowing begins as pharyngeal muscles contract and the bolus is moved toward the stomach via peristaltic waves.
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What is the falciform ligament?
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The falciform ligament is a sheet of mesentery that is a remnant of the ventral mesentery between the liver and the anterior wall of the peritoneal cavity.
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What is the function of the lesser omentum?
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The lesser omentum stabilizes the position of the stomach and provides an access route for blood vessels (and other structures) entering or leaving the liver.
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Explain the significance of peritoneal fluid.
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Peritoneal fluid separates the parietal and visceral surfaces of the peritoneal cavity and prevents friction and subsequent irritation during sliding movement or organs within the abdominal cavity.
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Name the four major regions of the stomach in order from its connection with the esophagus to the small intestine.
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The four regions of the stomach are the cardia, fundus, body , and pylorus.
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Describe the inner lining of the stomach.
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The inner lining of the stomach contains rugae, mucosal rugae, mucosal folds in the lining of the empty stomach that disappear as gastric distension occurs.
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What anatomical feature of the stomach allows the organ to form chyme?
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The longitudinal, circular, and oblique orientations of the muscle fibers in the three layers of the muscularis externa allow for the mixing and churning actions necessary for chyme formation.
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What is the function of parietal cells?
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Parietal cells secrete intrinsic factor and hydrochloric acid (HCI).
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Describe the alkaline tide.
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The alkaline tide is a sudden influx of bicarbonate ions in to the bloodstream from active parietal cells; it causes a temporary increase in blood pH.
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Explain the significance of the alkaline mucous layer lining the interior surface of the stomach.
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The alkaline mucous layer protects epithelial cells against the acid and enzymes in the gastric lumen.
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Name the layers of the small intestine from superficial to deep.
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The layers of the small intestine from superficial to deep are the mucosa, submucosa, muscularis externa, and serosa.
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Describe the anatomy of the intestinal mucosa.
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The intestinal mucosa bears transverse folds called plicae circulares bearing small projections called intestinal villi. These folds and projections increase the surface area available for absorption. Each villus contains a terminal lymphatic capillary called a lacteal. Between the bases of the villi are intestinal glands lined by enteroendocrine, mucous, and stem cells.
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Explain the function of lacteals.
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Lacteals are lymphatic capillaries in the intestinal villi that transport absorbed fatty acids that cannot enter blood capillaries.
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Name the three regions of the small intestine from proximal to distal.
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The three regions of the small intestine are the duodenum, jejunum, and ileum.
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Identify the region of the small intestine found within the epigastric region.
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The proximal portion of the duodenum is found within the epigastric region.
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What is the primary function of the duodenum?
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The primary function of the duodenum is to receive chyme from the stomach and neutralize its acids to avoid damaging the absorptive surfaces of the remaining regions of the small intestine.
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Name the five major hormones that regulate digestive activities.
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The five major hormones that regulate digestive activity are gastrin, secretin, gastric inhibitory peptide (GIP), cholecystokinin (CCK), and vasoactive intestinal peptide (VIP).
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Does a high-fat meal raise or lower the level of cholecystokinin (CCK) in the blood?
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The high-fat meal raises the cholecystokinin (CCK) level in the blood.
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How would the pH of the intestinal contents be affected if the small intestine did not produce secretin?
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If the small intestine did not secrete secretin, the pH of the intestinal contents would be lower (more acidic) than normal, because secretin stimulates the pancreas to release a fluid high in chyme entering the duodenum from the stomach.
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Name and briefly describe an important characteristic of each of the three overlapping phases of gastric secretion.
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The three overlapping phases of gastric secretin (which are named according to the location of the control center involved) are the cephalic phase, which prepares the stomach to receive ingested materials; the gastric phase, which begins with the arrival of food in the stomach ; and the intestinal phase, which controls the rate of gastric emptying.
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Describe two central reflexes triggered by stimulation of the stretch receptors in the stomach wall.
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The two central reflexes triggered by stimulation of stretch receptors in the stomach wall are the gastroenteric reflex, which stimulates motility and secretion along the entire small intestine, and the gastroileal reflex, which triggers the opening of the ileocecal valve to allow passage of materials from the small intestine into the large intestine.
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Why might severing the branches of the vagus nerves that supply the stomach provide relief for a person who suffers from chronic gastric ulcers (sores on the stomach lining)?
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Severing the branches of the vagus nerves that supply the stomach would interrupt parasympathetic stimulation of gastric secretions, and the consequent reduction in acid secretions would provide some relief from gastric ulcers.
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Identify the segments of the large intestine and the four regions of the colon.
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The segments of the large intestine are the cecum, colon, and rectum; the four regions of the colon are the ascending colon, transverse colon, descending colon, and sigmoid colon.
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Name the major functions of the large intestine.
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The major functions of the large intestine are (1) the reabsorption of water and the compaction of material into feces, (2) the absorption of vitamins produced by bacteria, and (3) the storage of fecal material prior to defecation.
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Describe mass movement.
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Mass movements are powerful peristaltic contractions that occur a few times daily in response to distension of the stomach and duodenum.
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Define hemorrhoids.
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Hemorrhoids are distended (swollen) veins in the distal portion of the rectum that may result from straining during defecation.
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Compare the structural features of the large intestine and the small intestine.
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The large intestine is larger in diameter and shorter in length than the small intestine, but its relatively thin wall lacks villi and has an abundance of mucous cells and distinctive intestinal glands (dominated by mucous cells).
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Describe the two positive feedback loops involved in the defecation reflex.
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The two positive feedback loops in the defecation reflex are (1) the short reflex, whereby stretch receptors in the rectal walls promote a series of peristaltic contractions in the colon and rectum, moving feces into the anal canal; and (2) the long reflex, whereby parasympathetic motor neurons in the sacral spinal cord, also activated by stretch receptors, stimulate peristalsis via motor commands distributed by somatic motor neurons.
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Name the three pairs of salivary glands.
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The three pairs of salivary glands are the parotid, sublingual, and submandibular salivary glands.
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Which glandular secretions contribute least to saliva production?
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The sublingual salivary glands contribute least (about 5 percent) to the secretions that make up saliva.
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The digestion of which nutrient would be affected by damage of the parotid salivary glands?
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Damage to the parotid salivary glands, which secrete the enzyme salivary amylase, woudl interfere with the digestion of starches (complex carbohydrates).
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Name the lobes of the liver.
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The liver is divided into left, right, caudate, and quadrate lobes.
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What is the function of the gallbladder?
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The gallbladder temporarily stores bile produced by the liver.
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What structure marks the division between the left lobe and right lobe of the liver?
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The falciform ligament marks the division between the left lobe and the right lobe of the liver.
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Define hepatocyte.
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A hepatocyte is a liver cell.
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Describe a portal area.
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A portal area is located at each of the six corners of a liver lobule; each portal area contains (1) a branch of the hepatic portal vein, (2) a branch of the hepatic artery, and (3) a small branch of the bile duct.
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Define Kupffer cells, and indicate their functions.
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Kupffer cells are liver macrophages that engulf pathogens, cell debris, and damaged blood cells.
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Define emulsification.
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Emulsification is the breakdown of lipid droplets by bile salts.
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What are the primary digestive functions of the gallbladder and pancreas?
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The gallbladder stores and releases bile, which contains additional buffers and bile salts that facilitate the digestion and absorption of lipids. The pancreas provides several digestive enzymes necessary for the breakdown of starches, lipids, nucleic acids, and proteins.
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Trace a drop of bile from the hepatic ducts to the duodenal lumen.
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The pathway of a drop of bile: hepatic ducts-> common hepatic duct-> common bile duct-> duodenal ampulla and papilla-> duodenal lumen
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Describe cholecystitis.
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Cholecystitis is inflammation of the gallbladder, usually resulting from a blockage of the cystic duct or the common bile duct b gallstones.
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What bacterium is responsible for the vast majority of peptic ulcers?
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The bacterium responsible for most peptic ulcers is Helicobacter pylori.
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Describe periodontal disease.
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Periodontal disease is characterized by a loosening of the teeth within the alveolar sockets due to erosion of the periodontal ligaments by acids produced by bacterial action.
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