A & P Chapter 23: The Digestive System – Flashcards
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Which layer of the alimentary canal is responsible for segmentation and peristalsis?
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muscularis externa
(Contractions of the circular and longitudinal layers of the muscularis externa produce the effects of peristalsis and segmentation. In the stomach, an additional muscle layer adds a twisting action.)
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Which layer of the alimentary canal contains not only glands and blood vessels but also a nerve plexus that helps regulate digestive activity?
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submucosa
(The submucosa layer contains blood and lymphatic vessels, lymphoid follicles, and the submucosal plexus of nerve fibers.)
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The __________ circulation drains all of the organs of the digestive system.
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hepatic portal
(The hepatic portal circulation drains all of the blood from the digestive organs and routes that blood through the liver for processing.)
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Which layer of the digestive tract controls digestive propulsion?
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muscularis externa
(The smooth muscles in the muscularis work to make the propulsive movements called peristalsis.)
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Unitary smooth muscle is found in all hollow organs except for the heart. What structure do both heart muscle and unitary smooth muscle share that allows them to contract as a functional group?
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gap junction
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Which digestive process does NOT occur in the mouth?
A. segmentation
B. mechanical breakdown
C. digestion
D. ingestion
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A. segmentation
(Segmentation is the back-and-forth mixing movement of food in the small intestine. The process of chewing and mixing food with saliva in the mouth is known as mastication.)
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What control mechanism opens the gastroesophageal sphincter?
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peristalsis in the esophagus
(As the peristaltic wave triggered by deglutition reaches the stomach, the gastroesophageal sphincter relaxes and allows food into the stomach.)
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Which of the following constitute a portal triad?
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a bile duct along with a portal venule and arteriole
(A bile duct along with a portal venule and arteriole constitute a portal triad. The blood vessels provide blood flow to the lobule and the bile duct drains bile.)
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Which of the following best describes the capillary wall structure found in the liver lobules?
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The capillary walls have openings that allow large proteins and small cells to pass through.
(The capillary walls in the lobules of the liver are sinusoidal and allow large proteins and even blood cells to pass, permitting the liver to perform its functions.)
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What is a major function of pancreatic juice?
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neutralizing chyme entering the small intestine from the stomach
(Pancreatic juice contains bicarbonate (as baking soda does) that can neutralize the pH of acidic chyme coming from the stomach.)
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Bile is secreted by the __________ under hormonal influence of __________.
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liver; secretion
(The liver secretes bile, especially when influenced hormonally by secretin.)
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Which of the following is NOT a secretion of the pancreas?
A. bicarbonate
B. nutrient enzymes
C. bile
D. insulin
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C. Bile
(Bile is secreted by the liver.)
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Which cells in the small intestine's mucosa secrete mucus?
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Goblet cells
(Goblet cells, which secrete mucus and are found in several areas of the digestive tract, are located on the villi of the small intestine.)
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Which of these best describes a lacteal?
A. special capillaries in the villi designed for absorbing food effectively
B. a projection of the small intestine wall designed to increase surface area
C. a deep pocket in the intestinal wall where endocrine and antimicrobial cells are located
D. a lymphatic vessel designed to help introduce fats to the blood
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a lymphatic vessel designed to help introduce fats to the blood
(Lacteals are lymphatic vessels located in the intestinal villi. Their ability to accept large materials makes them helpful in transporting large fat particles (called chylomicrons) into the lymph and eventually the bloodstream.)
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Most absorption of nutrients occurs in the __________.
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jejunum
(As digesting foods make their way through the jejunum, the majority of nutrients are absorbed at this time.)
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Which of the following propels food residue over large areas of the colon three to four times a day?
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mass movement
(Mass movement propels food residue over large areas of the colon three to four times a day. The defecation reflex occurs when the rectal wall stretches as mass movements force feces into it.)
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Which of the following is the primary physiological function of the large intestine?
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water absorption and feces elimination
(Water absorption and feces elimination are the primary physiological functions of the large intestine. The large intestine also provides a transport route and a surface for healthful bacteria.)
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What type of blood capillary located in this sublayer is uniquely suited for absorption of nutrient material?
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fenestrated (having perforations, apertures, or transparent areas)
