GI (pt 1/5) Basic Overview Flashcards
The esophagus is ___ cm long, and connects the mouth to the stomach.
25 cm
Where is the cricopharyngeus muscle located?
At the level of the aortic arch and mainstem bronchus.
At the level of the esophageal hiatus of the diaphragm.
-Food bolus here and foreign body impaction
What marks the transition of pharynx to esophagus?
UES
What marks the distal end of the esophagus, where it meets the stomach?
LES
What is the function of the LES?
Smooth muscle- function is to prevent reflux of gastric contents from stomach to esophagus.
-Impaired contraction or reduced tone of LES = reflux
-Increased tone or increased pressure of LES = impaired relaxation dysphagia
Which system dominates innervation of the GI tract?
Parasympathetic NS dominates - normal parts of digestion we don’t have to think about.
What is the effect of SNS stimulation of the GI tract?
Inhibit gastric secretion.
-However, in extreme stress SNS overpowers with increased catecholamines– diarrhea, vomiting. “Gut Brain”
What is the Enteric Nervous System (intrinsic)?
Mesh like system that governs the GI tract.
-large system that is part of the peripheral nervous system that functions independently of Central Nervous System (brain, spinal cord)
What are the 3 layers of the stomach?
1) Mucous Layer
2) Submucosal
3) Muscle
Describe the Mucous Layer of the stomach.
Thick; 95% water, phospholipids, mucin proteins, and HCO3.
Describe the Submucosal Layer of the stomach.
Veins and arteries are present.
-If mucous layer erodes into this layer you can have GI bleeding, ulcers.
Describe the Muscle Layer of the stomach.
If damaged- abdominal pain, rupture.
What is the main function of the Parietal Cells?
Main function is to secrete H+ via the H+/K+/ATPase pump, as well as the release of intrinsic factor.
What is intrinsic Factor?
A glycoprotein that helps you absorb B12.
-The only gastric secretion necessary for life.
-Binds to B12 and gets absorbed in the ileal epithelium.
-B12 is needed for the metabolism of every cell, DNA synthesis, and in the nervous system.
-Severe dysfunction/destruction that leads to IF deficiency will need B12 injections
What are the 3 Main Receptors of Parietal Cells?
1) Gastrin Receptor (CCK-B)
2) Acetylcholine Receptor (M3 Receptor)
3) Histamine Receptor (H2)
What is the Gastrin Receptor (CCK-B)?
Cholecystinkinen receptor
-Involves Gastrin
What is Gastrin?
A hormone secreted by G-cells into blood vessels in response to food/proteins.
-Released by vagal stimulation