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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
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
The enteric nervous system receives its inputs from ________.
autonomic neurons & sensory neurons in the wall of the GI tract
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
What membrane lines the abdominal cavity?
The technical word for chewing is _______.
Gastric reflux occurs when material flows backwards through which structure?
lower esophageal sphincter
The flow of chyme from the stomach to the small intestine is regulated by the _________.
What are rugae?
folds in the stomach that can flatten to expand the stomach volume
________ cells are responsible for secreting pepsinogen into the lumen of the stomach.
What do parietal cells secrete?
hydrogen ions & intrinsic factor
What do neck cells of gastric pits secrete?
What protects the stomach wall from the acidic lumenal contents?
the gastric mucosal barrier
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 ___________.
Name the sections of the small intestine, in order, from stomach to colon.
- 1. duodenum
- 2. jejunum
- 3. ileum
What is the brush border?
microvilli from epithelial cells lining the small intestine
Which sphincter of the GI tract is composed of skeletal muscle?
external anal sphincter
Name 4 components of saliva.
Original question text: "Which of the following is NOT one of the components of saliva?"
- -bicarbonate ions
Answer to original question: lipases
What structure secretes lipase?
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.
The absorption of glucose involves _______ across the apical membrane and _________ across the basolateral membrane.
secondary active transport; facilitated diffusion
In order to begin the process of fat digestion, the fat globules must be __________.
emulsified by bile salts
Emulsification aids in the digestion of fats by _________.
increasing the surface area of the fat globule exposed to enzymes
Pancreatic lipase degrades triglycerides into ________.
a monoglyceride and 2 free fatty acids
Digestion products of lipases are readily exchanged in the lumen with __________.
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
Vitamin B12 is absorbed in the ________ through _________.
ileum; complexing with intrinsic factor
A lack of intrinsic factor can result in ________.
The central component of the long reflex pathway typically involves the _______ nervous system, which acts to promote an increase in gastrointestinal activity.
The secretion of leptin causes ______.
decreased sensation of hunger
The increase in absorbed nutrients in blood will cause _______ secretion to increase, which decreases the sensation of hunger.
The presence of food in the duodenum will cause _______ secretion to increase, which decreases the sensation of hunger.
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.
The secretion of secretin is primarily regulated by _______.
acid content of the duodenum
Cholecystokinin faciltates digestion of fats by stimulating ________.
gall bladder contraction & relaxation of the sphincter of Oddi
Bile secretion is stimulated by _________.
Propelling food to the back of the mouth with the tongue initiates the _________.
Where in the GI tract would you find chyme, HCO3- , amylase, lipase, and nucleases?
Put the events of lipid breakdown in the correct order, starting with (A) large fat globules:
(A) large fat globules
(D) fat droplets
A, D, B, E, C
- 1. large fat globules
- 2. fat droplets
- 3. micelles
- 4. monoglycerides
- 5. chylomicrons
The secretion of pancreatic juice is stimulated by ________.