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53 Cards in this Set
- Front
- Back
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What's the other name for the gastrointestinal tract? Between what bodily landmarks does this tract stretch? |
Alimentary canal; from the mouth to the anus. |
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What are the three main accessory organs of the digestive system? |
Salivary glands, exocrine pancreas, liver and gallbladder. |
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What are the two types of digestion undertaken by the GI system? |
Mechanical and chemical |
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Where does the majority of absorption and secretion occur in the GI tract? |
Small intestine |
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What does the muscularis mucosa move? |
Villi in the GI tract |
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What type of epithelia makes up mucosa of the GI wall? |
Simple columnar |
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What type of tissue makes up the submucosa? |
Connective tissue |
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Where does the muscularis mucosa get its innervation from? |
The submucosal plexus |
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In the muscularis externa: Circular muscle contraction has this effect, and longitudinal muscle contraction has this effect: |
Circular muscles contract to narrow the lumen Longitudinal muscles contract to shorten the GI tract section. |
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Where are the three places where the myenteric plexus projects neurons to? What layer of the GI tract is the myenteric plexus located in? |
The myenteric plexus projects to circular and longitudinal muscle layer as well as the submucosal plexus. The myenteric plexus is located in the muscularis externa layer of the GI wall. |
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What layer of the GI wall serves to support the GI tract in the abdominal cavity? Where is this GI wall layer in relation to the other layers of the wall? |
Serosa; this is the outermost layer of the GI wall.
Layers in order from deep to superficial: Mucosa, submucosa, muscularis externa, serosa. |
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What layer of the GI wall is the muscularis mucosa located in? |
Mucosal layer (deepest) |
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What are the four components of the epithelial layer of the gut mucosa? |
Tall columnar epithelial cells (make up villi), goblet cells, enteroendocrine cells (at the base of villi), and stem cells. |
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What structure makes up the "brush border" present in the GI tract? |
Microvilli |
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What are lacteals? |
Lymphatic-associated vessels within the villi. |
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What two factors modify the "control systems" responsible for dictating conditions within the GI lumen? |
Volume and composition of lumenal contents |
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What bearing does extracellular fluid composition have on the conditions within the lumen of the GI tract? |
None! |
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There are four sensory "triggers" which will cause afferent signals to be sent from the gut. What are they? |
Stretch, endocrine hormones, nutrients, inflammation. |
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What nervous route do afferent signals from the GI tract take to reach the brainstem? |
They travel along the Vagus nerve. |
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Afferents from the GI tract can synapse in any of four locations. What are they? |
- Enteric NS - prevertebral ganglia - spinal cord - Brainstem |
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CNXII has what effect on the GI system? |
Motor impulses to the tongue. |
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What nerve controls the exterior anal sphincter? |
The pudendal nerve |
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What cranial nerves are in charge of swallowing? |
CNIX (glossopharyngeal) CNX (vagus) |
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What neurotransmitter is used by the sympathetic system to send signals to the GI tract? What's the function of sympathetic signals to the GI tract? |
Norepinephrine; inhibitory (relax digestion-inducing muscles) |
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Where do post-ganglionic fibers for the sympathetic nervous system to the gut end up? What about post-ganglionic fibers for parasympathetic system to gut? |
Sympathetic: Go to enteric nervous system Parasympathetic: Go via the vagus or pelvic nerves to local targets |
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How do you describe the effects of parasympathetic nervous signals to gut tissues? |
Stimulatory or inhibitory (but usually stimulatory); it depends on the final neurotransmitter receptor in the path |
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What neurotransmitter does the parasympathetic system utilize to send signals to the gut? |
Acetylcholine |
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The myenteric plexus is being stimulated: - What muscle layer is being activated? - What are five side-effects of this stimulation? |
Muscularis externa; 1) tone of gut wall is increased 2) Intensity of rhythmic gut contractions increases 3) Frequency of rhythmic gut contractions increases 4) Conduction velocity across the gut wall is increased 5) Sphincter constriction is inhibited |
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What plexus is responsible for controlling minute segments of the GI tract? |
The submucosal plexus |
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By stimulating this nervous plexus, you can control: absorbtion, secretion, and contraction of mucosal muscle. These actions can be described via this special method of regulating gut function: |
Submucosal; activation of this is an example of local control |
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Where is the main location of gastrin release? |
The antrum (bottom of the stomach) |
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Where is ghrelin released in the GI tract? |
Only the antrum (bottom of the stomach) |
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These four gut hormones are released primarily in the duodenum and jejunum (the first two segments of the small intestine) |
CCK, Secretin, GIP, Motilin |
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These GI hormones are only released in the duodenum and jujenum |
GIP, motilin |
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H+ ions stimulate secretion of this gut hormone, and inhibit secretion of this one: |
Stimulate: Secretin Inhibit: Gastrin |
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What gut hormone's release is stimulated by absence of nutrients? |
Ghrelin |
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Glucose will trigger secretion of this GI hormone |
GIP (also, GLP-1) |
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What stimulates the release of CCK? Where's it released? |
Fatty acids, also amino acids and peptides. Released primarily in duodenum, jejunum |
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Two triggers for gastrin release? Also– what inhibits gastrin release? |
Release is stimulated by presence of - Amino acids, peptides - Distension Inhibited by H+ |
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Two secretory effects promoted by gastrin: |
Increases histamine release, H+ secretion |
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What GI hormone increases HCO3 secretion and pepsin secretion, but decreases gastric acid secretion? |
Secretin |
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What are the four effects of CCK (not counting the "trophic effects on the pancreas")? |
1) Increase pancreatic enzyme secretion 2) Increase gallbladder contraction 3) Decrease gastric emptying 4) Decrease gastric acid secretion |
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GIP and GLP-1 have two effects. Name them: |
1) Increase insulin's response to glucose 2) Decrease gastric acid secretion |
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What does motilin do? What triggers its release? |
It increases gastric and intestinal motility. It's unknown what triggers the release of motilin. |
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This hormone stimulates an increase in hunger: |
Ghrelin |
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Three hormones decrease gastric acid secretion. What are they? |
Secretin, CCK, GIP/GLP-1 |
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What are the two paracrine molecules used in the GI tract? What molecular triggers cause their release? |
Histamine (released by gastrin), somatostatin (released by luminal H+). |
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What type of GI cells secrete somatostatin? |
D cells |
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What five pieces of the GI system use skeletal muscle? |
1) Mouth 2) Oropharynx 3) Upper esophageal sphincter 4) Upper 1/3 of the esophagus 5) External anal sphincter |
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What occurs in the liver immediately after a meal (postprandial)? |
Extreme vasodilation to allow for enhanced motility, secretion, digestion, and absorption |
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Three local control factors of the splanchnic circulation system: |
- GI hormones - Paracrines (ie– NO) - Decrease in O2 (as brought on by adenosine) |
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What's the effect of the sympathetic nervous system on the liver? |
Vasoconstriction |
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Venous outflow from most of the GI tract will quickly end up travelling through this blood vessel |
Hepatic portal vein |
