D313 Anatomy and Physiology II - Set 1 - Part 2

Correct Answer: Duodenum, jejunum, ileum

Option d is correct because the three subdivisions of the small intestine from proximal to distal are the duodenum, then the jejunum, then the ileum connecting to the large intestine. Option a is incorrect because it places the jejunum before the duodenum, but the duodenum is the first section receiving chyme from the stomach through the pyloric sphincter, not the jejunum. Option b is incorrect because it reverses the entire sequence by placing the ileum first, when the ileum is actually the last and longest section connecting to the large intestine. Option c is incorrect because it places the ileum between the duodenum and jejunum, but the correct middle section is the jejunum, with the ileum being the final and most distal segment.

Correct Answer: Circular folds, villi, and microvilli

Option b is correct because the three structural adaptations of the small intestine that dramatically increase absorptive surface area are circular folds, villi, and microvilli working together. Option a is incorrect because rugae are the expandable folds found inside the stomach, not the small intestine, and they do not contribute to the intestinal absorptive surface area increase. Option c is incorrect because rugae are stomach structures and do not belong to the small intestine, so they cannot be one of the three adaptations that increase intestinal absorption. Option d is incorrect because rugae are stomach folds and crypts of Lieberkuhn are secretory glands at the base of villi, neither of which are surface area adaptations for absorption.

Correct Answer: Duodenum

Option a is correct because the duodenum is the first section of the small intestine where pancreatic enzymes and bile are delivered, making it the primary site for chemical digestion. Option b is incorrect because the jejunum is the middle section of the small intestine primarily responsible for absorbing the nutrients that were digested in the duodenum, not receiving digestive secretions. Option c is incorrect because the ileum is the last section of the small intestine responsible for absorbing specific nutrients like Vitamin B twelve, not the primary chemical digestion location. Option d is incorrect because the cecum is the first part of the large intestine that receives material from the ileum through the ileocecal valve and is not a subdivision of the small intestine.

Correct Answer: Lacteals

Option c is correct because lacteals are specialized lymphatic vessels found within the villi of the small intestine that absorb digested lipids and transport them into the lymphatic system. Option a is incorrect because venules are small veins that carry deoxygenated blood away from capillary beds and are part of the blood vascular system, not the lymphatic fat absorption route. Option b is incorrect because capillaries within the villi absorb carbohydrates and amino acids into the bloodstream, but lipids bypass blood capillaries and enter the lacteals instead for lymphatic transport. Option d is incorrect because arterioles are small arteries that deliver oxygenated blood to capillary beds and play no direct role in absorbing digested fat molecules from the intestinal lumen.

Correct Answer: Brunner's glands

Option d is correct because Brunner's glands are found specifically in the duodenum and secrete alkaline mucus that neutralizes acidic chyme from the stomach to protect the intestinal wall. Option a is incorrect because crypts of Lieberkuhn are glands at the base of the villi that secrete lysozyme for antimicrobial defense, not the alkaline mucus that neutralizes stomach acid. Option b is incorrect because gastric glands are located in the stomach mucosa and contain cells that secrete acid and enzymes for gastric digestion, not alkaline protective mucus in the intestine. Option c is incorrect because salivary glands are located in and around the oral cavity producing saliva for moistening food and beginning starch digestion, not protecting the intestinal lining.

Correct Answer: Nasopharynx

Option a is correct because the nasopharynx is the most superior section of the pharynx and functions exclusively as an airway passage, never allowing food to pass through during normal swallowing. Option b is incorrect because the oropharynx is the region where both air and food share a common pathway, and it is the first pharyngeal section that food enters after leaving the mouth. Option c is incorrect because the laryngopharynx is the most inferior section of the pharynx where the digestive and respiratory pathways diverge toward the esophagus and the larynx respectively. Option d is incorrect because the esophagus is not a section of the pharynx at all but rather a muscular tube that receives the food bolus after it passes through the pharynx.

Correct Answer: Buccal phase

Option c is correct because the buccal phase is the only voluntary phase of swallowing, during which the tongue compresses chewed food into a bolus and consciously pushes it toward the pharynx. Option a is incorrect because the pharyngeal phase is entirely reflexive, involving automatic actions like the soft palate rising and the epiglottis closing over the airway during swallowing. Option b is incorrect because the esophageal phase is involuntary and involves automatic peristaltic contractions of the esophageal muscularis that push the bolus downward toward the stomach without conscious input. Option d is incorrect because the gastric phase refers to a stage of gastric secretion regulation that occurs when food arrives in the stomach, and it is not one of the three phases of swallowing.

Correct Answer: Laryngopharynx

Option d is correct because the laryngopharynx is the most inferior pharyngeal section and serves as the divergence point where food is directed to the esophagus and air to the larynx. Option a is incorrect because the nasopharynx is the most superior section of the pharynx located behind the nasal cavity and serves only as an airway, not a branching point for food. Option b is incorrect because the oropharynx is the middle section of the pharynx where food and air share a pathway, but it is not the inferior branching point described in the question. Option c is incorrect because the buccal cavity is another name for the oral cavity where food is chewed and formed into a bolus, and it is not a section of the pharynx at all.

Correct Answer: Epiglottis

Option b is correct because the epiglottis is a flap of elastic cartilage that reflexively folds over the tracheal opening during the pharyngeal phase of swallowing to prevent food from entering the airway. Option a is incorrect because the soft palate rises during swallowing to seal off the nasopharynx and prevent food from entering the nasal passages, not the trachea or lower airway. Option c is incorrect because the uvula is the small tissue projection hanging from the soft palate that assists in sealing the nasopharynx, but it does not cover the tracheal opening. Option d is incorrect because the tongue pushes the food bolus toward the pharynx during the voluntary buccal phase of swallowing but does not fold over the trachea to protect the airway.

Correct Answer: Oropharynx

Option a is correct because the oropharynx is the pharyngeal region immediately posterior to the oral cavity, and it is the first section that food enters after being pushed from the mouth. Option b is incorrect because the laryngopharynx is the most inferior section of the pharynx that food reaches after passing through the oropharynx, making it the second pharyngeal region food contacts. Option c is incorrect because the nasopharynx is the uppermost section dedicated solely to airflow, and the soft palate seals it off during swallowing to prevent any food from entering it. Option d is incorrect because the esophagus is located below the pharynx and receives the food bolus only after it has traveled through both the oropharynx and laryngopharynx sections first.

Correct Answer: Esophagus

Option d is correct because the esophagus is the muscular tube positioned posterior to the trachea that carries the swallowed bolus from the pharynx down to the stomach via peristalsis. Option a is incorrect because the pharynx is the throat region located superior to the esophagus that serves as a shared passageway for food and air before food enters the esophagus. Option b is incorrect because the trachea is the windpipe that carries air to the lungs and sits anterior to the esophagus, and food should never enter the trachea during normal swallowing. Option c is incorrect because the duodenum is the first segment of the small intestine located below the stomach, which is far downstream from the structure connecting the throat to the stomach.

Correct Answer: Upper esophageal sphincter

Option a is correct because the upper esophageal sphincter is located at the junction between the pharynx and the esophagus and relaxes during the pharyngeal phase to allow the bolus to enter. Option b is incorrect because the pyloric sphincter is located at the inferior end of the stomach and controls the release of chyme from the stomach into the duodenum of the small intestine. Option c is incorrect because the lower esophageal sphincter is located at the junction between the esophagus and the stomach and controls the entry of the bolus into the stomach, not the pharynx. Option d is incorrect because the ileocecal valve is located at the junction between the ileum and the cecum, controlling the passage of material from the small intestine into the large intestine.

Correct Answer: Lower esophageal sphincter

Option c is correct because the lower esophageal sphincter is formed in part by a portion of the diaphragm and controls the passage of the swallowed food bolus from the esophagus into the stomach. Option a is incorrect because the upper esophageal sphincter is located at the top of the esophagus where it meets the pharynx and is not associated with the diaphragm or stomach entry. Option b is incorrect because the pyloric sphincter is located at the exit of the stomach leading into the duodenum and controls chyme release, not food entry from the esophagus. Option d is incorrect because the internal anal sphincter is located at the terminal end of the large intestine and controls involuntary fecal retention, having no connection to the esophagus or diaphragm.

Correct Answer: Oropharynx, laryngopharynx, upper esophageal sphincter, esophagus, lower esophageal sphincter

Option b is correct because the swallowing pathway proceeds from the oropharynx to the laryngopharynx, through the upper esophageal sphincter, down the esophagus, and through the lower esophageal sphincter. Option a is incorrect because it reverses the pharyngeal sections by placing the laryngopharynx before the oropharynx, when food actually enters the oropharynx first after leaving the mouth. Option c is incorrect because the nasopharynx is an airway-only passage that is sealed off by the soft palate during swallowing, so food never travels through it under normal conditions. Option d is incorrect because it places the upper esophageal sphincter before the pharynx, when the sphincter is actually located at the bottom of the pharynx as the entry point into the esophagus.

Correct Answer: Peristalsis

Option d is correct because peristalsis is the wave-like contraction and relaxation of smooth muscle in the esophagus that actively pushes the bolus toward the stomach regardless of body position. Option a is incorrect because segmentation is a localized mixing contraction found primarily in the small intestine that churns food back and forth without significant forward movement through the tract. Option b is incorrect because haustral contractions are short, localized movements found in the large intestine that mix fecal contents to promote water absorption, not esophageal transport. Option c is incorrect because mass movements are large wave-like contractions occurring in the large intestine that push fecal material toward the rectum, not bolus movement through the esophagus.

Correct Answer: Chyme

Option c is correct because chyme is the semi-liquid mixture formed when the stomach churns and mixes swallowed food with gastric juices including hydrochloric acid and digestive enzymes before intestinal release. Option a is incorrect because a bolus is the ball of chewed food and saliva that is formed in the mouth during chewing and swallowing, before the food ever reaches the stomach. Option b is incorrect because feces is the solid waste material formed in the large intestine after water and nutrients have been absorbed, representing the final stage of the digestive process. Option d is incorrect because chyle refers to the milky lymphatic fluid containing absorbed dietary fats that travels through the lacteals and lymphatic system after fat absorption in the small intestine.

Correct Answer: Muscularis externa

Option a is correct because the muscularis externa is the smooth muscle layer that generates the powerful peristaltic and churning contractions responsible for both propulsion and mechanical mixing within the stomach. Option b is incorrect because the submucosa is the connective tissue layer containing blood vessels and nerves that supports the mucosa, but it does not generate muscular contractions for food movement. Option c is incorrect because the mucosa is the innermost lining involved in secretion and absorption and contains glandular cells, but it lacks the smooth muscle needed to produce churning movements. Option d is incorrect because the serosa is the outermost protective membrane that reduces friction between the stomach and neighboring organs and plays no role in generating muscular contractions.

Correct Answer: Fats

Option d is correct because fats have the strongest effect on slowing gastric emptying, which is why high-fat meals remain in the stomach longer and produce a prolonged feeling of fullness. Option a is incorrect because carbohydrates do not significantly slow gastric emptying compared to fats, and simple carbohydrate-rich liquids tend to pass through the stomach relatively quickly. Option b is incorrect because while proteins can briefly stimulate gastric activity, they do not slow gastric emptying to the same degree as fats, which have the most pronounced inhibitory effect. Option c is incorrect because vitamins are micronutrients that do not have a significant independent effect on gastric emptying rate and are not classified as macronutrients that influence stomach motility.

Correct Answer: Parasympathetic nervous system

Option b is correct because the parasympathetic nervous system stimulates gastric emptying and generally promotes digestive activity including increased motility, secretion, and the release of chyme into the duodenum. Option a is incorrect because the sympathetic nervous system generally inhibits digestive activity as part of the fight-or-flight response, slowing gastric emptying rather than promoting it during stress. Option c is incorrect because the somatic nervous system controls voluntary skeletal muscle movements like chewing and the buccal phase of swallowing, but it does not regulate involuntary gastric emptying. Option d is incorrect because the central nervous system is a broad term for the brain and spinal cord, and the question specifically asks which division of the autonomic nervous system drives gastric emptying.

Correct Answer: Proteins

Option c is correct because the stomach primarily digests proteins through the action of pepsin, which is activated by hydrochloric acid and breaks peptide bonds in protein molecules within the stomach. Option a is incorrect because carbohydrate digestion begins in the mouth with salivary amylase and is largely completed in the small intestine, while the acidic stomach environment actually inactivates salivary amylase. Option b is incorrect because lipid digestion occurs primarily in the small intestine where bile emulsifies fats and pancreatic lipase breaks them down, with only minor gastric lipase activity in the stomach. Option d is incorrect because nucleic acid digestion is not a primary function of the stomach and occurs mainly through pancreatic nucleases acting in the small intestine during later stages of digestion.