Introduction to GI Flashcards
What is the order of tissue layers within the GI tract from the outside in?
"SMSM" Serosa Muscularis Submucosal Mucosal
What is the Serosa layer composed of?
Composed of connective tissue and covered by squamous epithelial cells.
What is the Muscularis layer composed of and what function does it have?
Longitudinal and circular smooth muscle.
This layer regulates peristalsis.
What is the submucosal layer composed of and what function does it have?
Contains many large blood vessels, glands, and connective tissue.
Function not spoken of.
What is the mucosal layer composed of and what function does it have?
Composed of the lamina propria and lamina muscularis mucosa.
Helps coordinate bowel movements.
What layer can the lamina propria be found in and what is it composed of?
Found within the mucosal layer, composed of capillaries, neurons, and immune cells.
What layer can the lamina muscularis be found in and what action does it have?
Found within the mucosa layer with the action of coordinating GI motility.
What is neurocrine communication?
Neurons innervate endocrine, vascular, or muscle cells to modulate there function.
What effect does Acetylcholine have on the gut?
Excitatory causing:
Vasodilation
Increased secretions
Smooth muscle contraction.
What effect does norepinephrine have on the gut?
Inhibitory causing:
Vasoconstriction
Inhibits smooth muscle contractions
Decreases secretions.
Interneurons of the ENS that release serotonin have what effect on the GI?
Excitatory inducing:
Vasodilation
Increases smooth muscle contraction
Stimulates secretion.
Dopamine released by the ENS stimulates what sort of reaction within the GI?
Dopamine is inhibitory and stops ENS neuronal firing.
What effect does NO released from the ENS have on the GI?
Inhibitory causing:
Smooth muscle relaxation
(Vascular and GI)
What effect does Vasoactive intestinal peptide (VIP) released from the ENS have on the GI?
VIP is inhibitory and causes smooth muscle relaxation
Vascular and GI
Blood flow to and from the GI tract is known as ?
Splanchnic circulation
Blood flows from the organs of the GI tract and eventually empties into the …?
Portal vein which carries the blood to the liver.
Blood that has gone through the liver is returned to the body via the?
The hepatic vein.
What is the resting slow wave?
A continuous depolarization followed by a repolarization that does not ellicit a contraction.
This is the membrane potential that the gut displays.
What is the spike potential?
Potential for rapid depolarization in the presence of stimuli such as stretch or acetylcholine.
This stimulus will likely result in contraction/ a spike.
What sort of GI activities are mediated by the segmental contractions of the GI?
Mixing activities.
When comparing peristalsis to segmental mixing contractions, you will find that segmental mixing contractions tend to be….
Increased in contraction frequency leading to the movement of food toward the anus.
When is reverse peristalsis typically seen?
Typically seen in storage movements within organs such as the stomach or colon.
What is the migrating motor complex?
A long rhythmatic contraction that occurs during a fasting state activated by multiple stimuli.
Which hormone plays an important role in regulating and initiating the MMC?
Motilin
In addition to motilin, what nervous systems also play a role in the MMC?
The vagus nerve and the ENS.
