Exam (elaborations)
BIO 252 Final Exam Study Guide Latest Questions And Answers
- Course
- Bio 114
- Institution
- Arizona State University
BIO 252 Final Exam Study Guide Latest Questions And Answers
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BIO 252 Final Exam StudyGuide Latest Questions And
Answers
✅✅
digestive tract (aka GI tract) - -Covering an internal lumen (which is
actually "outside" the body)
The disassembly line of our body
accessory digestive organs - ✅✅-Teeth, pancreas, assisting in
mechanical and chemical digestion
✅✅
Which of the following best describes the role of the esophagus in
digestion? - -Connects the mouth to the stomach and has no role in
chemical digestion
It's role is just propulsion
3 roles of the stomach - ✅✅ -1. Storage facility. Most digestion happens in
the small intestine so we just don't have enough room so we need to store
in in stomach
2. Disassembly. First step in digestion of proteins. It's not essential, but it's
difficult without it.
3. Defense. Acidic environment gets rid of pathogens.
rugae - ✅✅ -These are the foldings inside the stomach that allow the
stomach to expand and then it makes it so it doesn't tear apart when it
stretches
fundus - ✅✅ -store room in the stomach where some of the food waits
until we can deal with it.
3 smooth muscle layers in the stomach - ✅✅ -Longitudinal muscle most
external
Circular muscle within that
And then most deep, oblique muscle
The cells lining the stomach secrete mucin (mucous)
The lining is dotted with millions of gastric pits
What structural modification underlies the stomach's ability to mechanically
,either delivered in small amounts to the duodenum or forced backward into
the stomach for further mixing
The curious case of Alexis St Martin - ✅✅ -Dr. William Beaumont
In michigan, wanted to study the stomach and body
Alexis St Martin was shot and it went through left part of body. Went
through stomach and out
Took different types of food and tied it to a string and put it in his stomach
and waited and took it out to see if it was digested or not.
Mucous neck cells - ✅✅ -in the gastric glands.
Secrete a thin mucous layer
✅✅
Parietal cells - -in the gastric glands. Secrete intrinsic factor and
hydrochloric acid
Intrinsic factor has nothing to do with stomach. Really is just important
protein that has receptors on walls of small intestine that binds to essential
vitamin (B12) because it can't be digested by itself
There is a sublingual supplement (put it under your tongue)
This lets you absorb B12 directly into the capillaries in the bottom of your
mouth
Chief cells -✅✅ -in the gastric glands. Secrete pepsinogen. This gets
modified and becomes an active enzyme. Becomes an enzyme in an acidic
environment called pepsin. Pepsin can do digestion of proteins. Acidic
environment comes from HCL from parietal cells
HCL assists in pepsin synthesis and activity
Breaking down cell walls of plant foods
Defense against pathogens
✅✅
gastric juice - -Mucus, HCL, pepsinogen
Secreted to the lumen
Enteroendocrine cells - ✅✅ -G cells: Gastrin
Gastrin will go back and promote secretion of gastric juice
✅✅
How does gastrin from the bottom make it to parietal cells and chief cells? -
-Gastrin is a protein that serves as a hormone so it goes through the
blood vessels.
Dave Barnes had agonizing pain in his abdomen, followed by heartburn
, From the gut
Acts as an independent system. More neurons here than in whole spinal
cord
All local reflexes
The nervous system of the stomach
Long reflexes (interacts with the brain)
Parasympathetic. Medulla oblongata controls gastric secretion and vagus
nerve goes all the way down to the stomach
Three phases of regulation - ✅✅-Cephalic (head)
Gastric (stomach)
Intestinal (duodenum)
✅✅
What does NOT stimulate the secretion of HCl in the stomach? -
-Secretin
Secreted by the small intestine and it inhibits gastric activity
✅✅
Peristaltic waves move toward the pylorus at the rate of 3 per min. How? -
-We have cells that determine the pace
regulation of gastric emptying - ✅✅ -In general, the same mechanisms
regulating gastric secretion will also regulate gastric emptying (mainly:
intestinal phase)
Carb-rich chyme quickly moves through the duodenum (4 hours)
Fat-laden chyme is digested more slowly causing food to remain in the
stomach longer (~6 hours)
vomiting -✅✅ -Stimulation of the vomiting center in the medulla
Increase in the intraabdominal pressure, relaxation of the esophageal
sphincter, and elevation of the soft palate, closing the connection between
the oropharynx and nasopharynx
from where is bile secreted? - ✅✅-liver
✅✅
Which system will send signals to the hepatopancreatic sphincter NOT to
contract, and when? - -When it is contracted nothing passes through
Sympathetic says no digestion when you are stressed
Intestinal phase tells it not to contract because chyme is already in it
✅✅
mucosa layer lines the wall of the duodenum to do what? -
-Adaptation to digestion and absorption: fold within a fold
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