BIO 252 FINAL EXAM GUIDE QUESTIONS AND SOLUTIONS

Describe the Enteric Nervous System - Part of the ANS as a division/ parallel of the Parasympathetic.
It is a LOCAL system, has more neurons that the spinal cord and is called the "small brain".
Since it is local it uses Local reflexes, but still does communicate with the CNS some via the Vegas
Nerve/Parasympathetic, so also long nerves
It is independent of the nervous system, it still gets signals but functions on its own ... wut (lets talk)
Long vs Local Reflex - Long involves the CNS while the local does not,
Describe what happens when you smell ravioli - Sense receptors signal to the CNS, CNS communicates
with ANS, the ANS sends long reflexes to cells of the digestive system to start creating Gastric juices.
Why is the Digestive Tract considered to be outside of your body? - It is exposed to the outside world via
the mouth and the bumhole. Basically is just a disassembly line.
What are the 2 parts of the Digestive System? - The Digestive Tract
The Accessory Organs (Teeth, Pancreas...)
How much digestion does the esophagus do? - None, trick question, hehe
The food is only in your throat for a few seconds so there is no digestion, only propulsion.
What are the 4 parts of the stomach? - Cardia - Top part near Heart
(Cardiac Sphincter
Fundus - Upper region, Little digestion here, just stores juices.
Body - main region of digestion
Pyloric Region - Bottom, but of course it is again subdivided into...
Pyloric Atrium which thins into the Pyloric Canal which ends at the Pyloric Sphincter.
What is the role of the Cardiac and Pyloric Sphincter? - Cardiac acts like a one way valve to allow food
down the esophagus and into the stomach and doesn't let stuff come up because of the acidity.
Pyloric is at the end of the stomach and connects to the small intestine, is used to let small portions at a
time into the small intestine for digestion
What are the 3 main roles of the stomach - Storage - It is real big and the small intestine needs time to
digest/absorb so it stores a lot of food until the small intestine is ready.
Digestion of Proteins - very important for this but does little for carbs and lipids.
Immune - Very acidic to help combat all of the pathogens you eat. YUM
What type of tissues faces the lumen? - Epithelial
What are the different types of muscles in the stomach and what do they do? - Longitudinal - fibers that
extend length of stomach (most external)
Circular - oriented beneath longitudinal at 90 degrees.
These are used for Peristalsis
Makes stomach unique cause it has 3...
Oblique - the most internal muscle that is diagonal to the other muscles and is responsible for
mechanical digestion (churning).
Wut is peristalsis - the involuntary contraction/relaxation of the longitudinal and circular muscles that
moves food down the GI Tract.
What happens if you eat upside down? - Your weird
But, the digestive process takes longer because it is working against gravity but peristalsis is still enough
to move the food along the GI Tract.
Describe Rugae and why they are important - Rugae are folds in the stomach lining so that when the
stomach expands to store food, the cells don't rip, they just unfold. Not neccesairly for increased surface
area. (TALK ABOUT RUGAE,SA, and PITS)
What is chyme - mixture of partially digested food and gastric juice (which came from the gastric glands
in the gastric pits).
This is usually what you throw up
What are the secreting cells of the gastric pits? - In the gastric pits, there are 4 groups of cells...
1) Parietal Cells - secrete
Intrinsic Factor - another slide
HCl - acidity to kill pathogens
2) Mucous Neck Cells - secrete mucin
Mucin + water = Mucus
3) Chief Cells - secrete Pepsinogen
Pepsinogen is not activated, until it is with HCl which makes pepsin which digests proteins.