FIRST PUBLISH OCTOBER 2024
FINAL bio 252 Exam Questions and
Answers
digestive tract (aka GI tract) - Ans:✔✔-Covering an internal lumen (which is actually "outside" the body)
The disassembly line of our body
accessory digestive organs - Ans:✔✔-Teeth, pancreas, assisting in mechanical and chemical digestion
Which of the following best describes the role of the esophagus in digestion? - Ans:✔✔-Connects the
mouth to the stomach and has no role in chemical digestion
It's role is just propulsion
3 roles of the stomach - Ans:✔✔-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 - Ans:✔✔-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
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fundus - Ans:✔✔-store room in the stomach where some of the food waits until we can deal with it.
3 smooth muscle layers in the stomach - Ans:✔✔-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 digest food? - Ans:✔✔-The
stomach has an extra group of muscles called the oblique muscles that are responsible for the churning
and mechanical digestion of food
chyme - Ans:✔✔-Gastric juice + digestive food
either delivered in small amounts to the duodenum or forced backward into the stomach for further
mixing
The curious case of Alexis St Martin - Ans:✔✔-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
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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 - Ans:✔✔-in the gastric glands.
Secrete a thin mucous layer
Parietal cells - Ans:✔✔-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 - Ans:✔✔-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 - Ans:✔✔-Mucus, HCL, pepsinogen
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Secreted to the lumen
Enteroendocrine cells - Ans:✔✔-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? - Ans:✔✔-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 and vomiting. The doctor told
him he has a gastric ulcer in his stomach, caused by the Helicobacter bacteria. It is most likely that the
bacteria: - Ans:✔✔-Penetrated the mucus layer of the stomach
enteric system - Ans:✔✔-Part of autonomic nervous system
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
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