Wednesday’s lecture covered topics of the digestive system. We learned the layers of the gastrointestinal tract and the various cells of the gastric glands, the substances they secrete, and how these substances aid in digestion. The muscularis layer of the tract is innervated by the parasympathetic nervous system, specifically the vagus nerve (cranial nerve X). This layer is comprised of smooth muscle and plays an important role in moving food along the digestive tract. The stomach plays an important role in the mechanical breakdown of food into chyme. The pancreas not only secretes important hormones for the endocrine system but also secretes important chemicals for digestion. The pancreatic acinar cells secrete digestive enzymes into the pancreatic duct, which meets the common bile duct from the liver at the hepatopancreatic ampulla, before they are released into the duodenum. The liver uses nutrients to create proteins and bile (which is secreted through the common bile duct and meets the pancreatic digestive enzymes at the hepatopancreatic ampulla). The small intestine contains folds of villi, each one which contains microvilli (“brush border”). We also discussed the difference between High density, low density, and very-low density lipoproteins.
As with any cranial nerve, the vagus nerve (X) plays a vital role in digestion. Not only does it keep your heart at a normal rate but it also aids in the release of digestive enzymes and smooth muscle contractions along your GI tract. I wonder then, what would happen if there was trauma to the vagus nerve and how this would affect your health (since its functions are so vital). I read online how some people’s vagus nerves were severed during surgery and now they are required to take medications to help with such things as a normal heart beat and digestive enzyme release. We definitely take for granted the role of our parasympathetic system (probably because we aren’t consciously aware of its functions!) but we would certainly realize how different life would be if our nerves did not work properly!
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Jordan - Check out this website http://digestive.niddk.nih.gov/ddiseases/pubs/gastroparesis/index.htm. It talks about gastroparesis. Gastroparesis occurs when the vagus nerve is damaged and the muscles of the stomach and intestines do not work normally. Food then moves slowly or stops moving through the digestive tract. One of the most common causes of gastroparesis - diabetes.
ReplyDeleteyou did a good job describing this part of the digestive system. It helped me understand it a little better. we went over some of this but not the high density, low density and very-low density lipoproteins and i couldn't find it in the book. I'll have to check on-line.
ReplyDeleteJordan, you are right we do take for granted our cranial nerves, perhaps it's because we are not aware of what they do and that they are working. I know for me since this class has started that I am grateful to be as healthy as I am. There is so many possibilities for things to go wrong, right from taking your first breath as a newborn.
ReplyDeleteI did some research re: the cranial nerves and this is what I came up with. When your stomach doesnt empty on time it's called Gastroparesis. The stomach normally contracts to move food down into the small intestine for digestion. The vagus nerve controls the movement of food from the stomach through the digestive tract. When the vagus nerve is damaged the muscles of the stomach and intestines do not work normally, food then moves slowly or stops moving through the digestive tract. One cause could be diabetes, surgery on the stomach or vagus nerve,viral infections, anorexia, narcotics that slows contractions, gastroesophageal reflux disease ( which I have and just learned something new), metabolic disease like hypothyroidism, ( which I have as well, WOW).
If food lingers to long it causes bacterial overgrowth from the fermation of food. You can be tested through endoscopy, ultrasound, barium x-ray and even a smart pill. You can treat with medication and dietary changes. Check out the cool web site that I found re: vagus nerve damage.
http://www.becomehealthynow.com/article/bodynervousadvanced/812/5/
You did an amazing job explaining the digestive system. Before A&P started I never knew how complex the human body was. And I agree with Candy, I'm very thankful to be as healthy as I am. Its amazing how each systems works with eachother to make the body function properly and if there is one little glitch it can throw everything off.
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