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Name the layers of the GI tract wall, in order, from lumen to external surface.
- 1. mucosa
- 2. submucosa
- 3. muscularis externa
- 4. serosa
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Enterocytes of the mucous membrane of the mucosal layer are classified as _________ if they secrete fluids and enzymes into the lumen and _________ if they release hormones into the bloodstream.
exocrine cells; endocrine cells
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The enteric nervous system receives its inputs from ________.
autonomic neurons & sensory neurons in the wall of the GI tract
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What muscle groups are found in the muscularis externa?
- inner circular layer capable of slow-wave potentials
- outer longitudinal layer that requires neural input for contraction
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What membrane lines the abdominal cavity?
peritoneum
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The technical word for chewing is _______.
mastication
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Gastric reflux occurs when material flows backwards through which structure?
lower esophageal sphincter
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The flow of chyme from the stomach to the small intestine is regulated by the _________.
pyloric sphincter
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What are rugae?
folds in the stomach that can flatten to expand the stomach volume
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________ cells are responsible for secreting pepsinogen into the lumen of the stomach.
chief
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What do parietal cells secrete?
hydrogen ions & intrinsic factor
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What do neck cells of gastric pits secrete?
mucus
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What protects the stomach wall from the acidic lumenal contents?
the gastric mucosal barrier
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To increase the absorptive efficiency of the small intestine, the surface area of the mucosa is increased by the presence of folds in the wall called ______, and projections of the cell membrane called ___________.
villi; microvilli
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Name the sections of the small intestine, in order, from stomach to colon.
- 1. duodenum
- 2. jejunum
- 3. ileum
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What is the brush border?
microvilli from epithelial cells lining the small intestine
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Which sphincter of the GI tract is composed of skeletal muscle?
external anal sphincter
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Name 4 components of saliva.
Original question text: "Which of the following is NOT one of the components of saliva?"
- -bicarbonate ions
- -mucus
- -amylases
- -lysozymes
Answer to original question: lipases
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What structure secretes lipase?
pancreas
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In order to convert amino acids to fatty acids and/or gluconeogenic precursors, an ammonium ion must be removed in the liver and converted to ________ before being excreted by the kidneys.
urea
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The absorption of glucose involves _______ across the apical membrane and _________ across the basolateral membrane.
secondary active transport; facilitated diffusion
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In order to begin the process of fat digestion, the fat globules must be __________.
emulsified by bile salts
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Emulsification aids in the digestion of fats by _________.
increasing the surface area of the fat globule exposed to enzymes
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Pancreatic lipase degrades triglycerides into ________.
a monoglyceride and 2 free fatty acids
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Digestion products of lipases are readily exchanged in the lumen with __________.
micelles
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Once the degradation products of triglycerides have entered the epithelial cells that line the small intestines, they ___________.
are reassembled into triglycerides and packaged by the Golgi apparatus into chylomicrons
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Vitamin B12 is absorbed in the ________ through _________.
ileum; complexing with intrinsic factor
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A lack of intrinsic factor can result in ________.
pernicious anemia
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The central component of the long reflex pathway typically involves the _______ nervous system, which acts to promote an increase in gastrointestinal activity.
parasympathetic
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The secretion of leptin causes ______.
decreased sensation of hunger
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The increase in absorbed nutrients in blood will cause _______ secretion to increase, which decreases the sensation of hunger.
insulin
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The presence of food in the duodenum will cause _______ secretion to increase, which decreases the sensation of hunger.
cholescystokinin
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In response to the presence of food within the duodenum, the increased release of _________ will primarily stimulate an increase in bicarbonate secretion from the exocrine pancreas.
secretin
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The secretion of secretin is primarily regulated by _______.
acid content of the duodenum
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Cholecystokinin faciltates digestion of fats by stimulating ________.
gall bladder contraction & relaxation of the sphincter of Oddi
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Bile secretion is stimulated by _________.
cholecystokinin (CKK)
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Propelling food to the back of the mouth with the tongue initiates the _________.
swallowing reflex
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Where in the GI tract would you find chyme, HCO3- , amylase, lipase, and nucleases?
duodenum
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Put the events of lipid breakdown in the correct order, starting with (A) large fat globules:
(A) large fat globules
(B) micelles
(C) chylomicrons
(D) fat droplets
(E) monoglycerides
A, D, B, E, C
- 1. large fat globules
- 2. fat droplets
- 3. micelles
- 4. monoglycerides
- 5. chylomicrons
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The secretion of pancreatic juice is stimulated by ________.
secretin
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