Term
| What are the 3 components of the small intestine? |
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Definition
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Term
| What are the 3 segments of the large intestine? |
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Definition
| Ascending, transverse, descending, sigmoid, rectum |
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Term
| What are accessory glands associated with the GI tract? |
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Definition
| Salivary glands, liver, gallbladder, pancreas |
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Term
| What is the role of the SNS and PSNS in GI innervation? |
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Definition
| GI tract not directly innervated by PSNS or SNS – these modify the GI tract only. GI tract has its own NS called enteric NS that can function independently |
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Term
| PSNS stimulation has what effect on GI tract? |
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Definition
| PSNS causes constriction of GI tract |
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Term
| What is the nervous system controlling the GI tract? |
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Definition
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Term
| What are the 5 layers of the GI tract going from outside to inside? |
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Definition
1. Serosa – outermost layer
2. Longitudinal muscles – smooth muscle
3. Circular muscles
4. Submucosa – glandular tissue, blood vessels, nerve fibers
5. Mucosa – absorbing surface, glandular secreting tissue |
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Term
| The outermost layer of GI tract is made up of what? |
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Definition
| Serosa layer - Connective tissue primarily that holds everything together |
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Term
| What is the function of the second layer of GI tract? |
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Definition
| Longitudinal layer – motility, peristaltic activity |
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Term
| What is the function of the third layer of GI tract? |
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Definition
| Circular layer – mixing movements |
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Term
| What is contained in the sub mucosal layer of GI tract? |
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Definition
| Glandular tissue, blood vessels, nerve fibers |
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Term
| What are the functions of the mucosal layer? |
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Definition
Mainly the absorbing surface
Glandular tissue for secreting into lumen
Variety of cells that will secrete or reabsorb depending on needs of body |
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Term
| If a pill is inside the lumen of the GI tract, is it considered a part of the body? |
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Definition
| Not considered part of the body until it is absorbed across lumen wall |
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Term
| Which nerve plexuses comprise the enteric NS? |
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Definition
Myenteric Plexus – Located b/w longitudinal and circular muscle layers
Deals with peristalsis and mixing
Contains pacemaker cells to maintain general tone of GI tract
Meissner’s Plexus – Submucosal plexus
Mainly concerned with secretory and absorption activity within the gut |
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Term
| Where is the myenteric nerve plexus located? |
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Definition
| Between longitudinal and circular muscle layers |
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Term
| What is the primary role of myenteric plexus? |
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Definition
Peristalsis and mixing
Pacemaker cells to maintain general tone of GI tract |
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Term
| Which nerve plexus contains pacemaker cells? |
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Definition
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Term
| Where is Meissner’s nerve plexus located? |
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Definition
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Term
| What is the main purpose of Meissner’s nerve plexus? |
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Definition
| Secretory and absorption activity in gut |
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Term
| Where is mucosal nerve plexus located? |
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Definition
| Located within mucosal layer |
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Term
| What is the function of the mucosal nerve plexus? |
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Definition
| Controls functions of mucosal barrier |
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Term
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Definition
Basal electrical rhythm
Basal electrical activity of gut and all of the nerve cells and muscle cells that occur normally all the time even in rested state |
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Term
| When the gut is at rest, what does an electrical tracing of GI tract look like? |
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Definition
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Term
| When there is peristaltic activity in the gut, what does the electrical tracing of the GI tract look like? |
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Definition
| Spikes ontop of the BER waves |
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Term
| What are causes of the spiking potentials? |
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Definition
| PSNS vagus stimulation, stretch, food, Ach |
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Term
| Epinephrine and norepinephrine have what effect on electrical tracing of GI tract? |
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Definition
| Diminutive or absence of BER slow waves |
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Term
| What is the BER for these parts of the GI tract: |
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Definition
Esophagus: 3-5/min
Stomach: 3-5/min
Duodenum: 12/min
Jejunum: 10/min
Ileum: 7-8/min
Colon: 3-5/min |
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Term
| Actual BER rate is determined by what factors? |
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Definition
Type of food in gut
Amount of food in gut
Amount of neural activity from PSNS (mainly vagus nerve) |
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Term
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Definition
| Change in BMR. Hyperthyroidism would increase BER |
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Term
| Which sphincter is located at the top of the esophagus? |
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Definition
| Superior esophageal sphincter |
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Term
| Which sphincter is located at the bottom of the esophagus? |
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Definition
| Lower esophageal sphincter or cardiac sphincter |
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Term
| Which sphincter is located between the stomach and the duodenum? |
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Definition
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Term
| Which sphincter is located between the ileum and large bowel? |
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Definition
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Term
| Which is the last sphincter of the GI tract? |
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Definition
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Term
| What is the result of PSNS stimulation on sphincters? |
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Definition
| PSNS causes inhibition of sphincters but increases general mvmts/peristalsis |
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Term
| What is the result of SNS stimulation on sphincters? |
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Definition
| SNS causes constriction of sphincters but relaxes general muscles of GI tract |
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Term
| What are the mediators of the SNS? |
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Definition
| Cathecholamines (epi, norepi) |
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Term
| Catecholamines have what effect on smooth muscle of GI tract? |
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Definition
| Inhibit smooth muscle, inhibit peristalsis, inhibit spiking on BER |
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Term
| What are the mediators of the PSNS? |
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Definition
| Ach, histamine, serotonin |
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Term
| What effect does the SNS have on spiking potential? |
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Definition
| Does not cause spiking potentials |
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Term
| What are the primary functions of the GI tract? |
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Definition
o Secretes
o Motility
o Absorption
o Excretion |
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Term
| What are the types of motility found in GI tract? |
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Definition
o Peristaltic/propulsive/transient
o Trituation: mixing and grinding motion |
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Term
| Where does most absorption in GI tract occur? |
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Definition
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Term
| Describe phase I of swallowing |
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Definition
o Voluntary action
o Food chewed until comfortable
o Food gets rolled up into bolus and is matted together with mucus from saliva
o When want to swallow, elevate tongue and push bolus of food to back of throat to pharynx – controlled by glossopharyngeal nerve |
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Term
| Describe phase II of swallowing |
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Definition
o Begins when food hits pharyngeal wall
o Completely involuntary
o Initiates the swallowing reflex controlled by deglutition center
o Deglutition center located in brain center |
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Term
| When does phase II of swallowing begin? |
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Definition
| When food hits pharyngeal wall |
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Term
| Where is the deglutination center located? |
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Definition
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Term
| Which phase of swallowing is voluntary? Involuntary? |
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Definition
o Voluntary is Phase I
o Involuntary is Phase II |
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Term
| What actions result from activation of deglutination center? |
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Definition
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Term
| What are the 3 primary pairs of salivary glands? |
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Definition
• Parotid
• Submaxillary
• Sublingual |
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Term
| Salivary glands are controlled by the ________ NS and the _______ and _____ nerves |
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Definition
| Extrinsic NS via facial and glossopharyngeal nerves |
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Term
| What controls nerve activity to salivary glands? |
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Definition
| Superior and inferior salivatory nuclei in brain |
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Term
| What is the primary role of the superior and inferior salivatory nuclei? |
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Definition
| Control rate of secretion |
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Term
| How much saliva is secreted by the 3 salivary glands? |
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Definition
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Term
| What are the components of saliva? |
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Definition
o Ptyalin (amylase)
o Mucus
o Lysosomes
o ABO blood groups
o Iodine
o Extracellular fluid |
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Term
| What is the function of amylase? |
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Definition
| Breaks down CHO into smaller CHO units |
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Term
| What is the function of lysosomes? |
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Definition
| Break down bacterial walls, antibacterial action |
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Term
| Which electrolytes are absorbed from saliva? |
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Definition
o Sodium actively
o Chloride passively |
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Term
| Which electrolytes are secreted into saliva? |
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Definition
o Potassium actively secreted
o Bicarbonate actively secreted |
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Term
| What are other actions of saliva? |
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Definition
o Lubricates oral cavity for speech
o Swallowing lubrication
o Dental health
o Antibacterial action
o Taste – food must be at least partially liquefied in order for taste buds to detect taste |
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Term
| What is mumps? What gland is usually affected? |
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Definition
| Viral infection of the parotid gland |
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Term
| What is sialolithiasis? What gland is usually affected? |
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Definition
| Formation of salivary stones usually in parotid gland |
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Term
| Damage to CN V, IX, X can cause what GI tract related problem? |
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Definition
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Term
| What is sjogren’s syndrome? |
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Definition
| Autoimmune disease that destroys salivary glands and tear ducts |
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Term
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Definition
| Extreme dry mouth syndrome, has multiple causes but is frequently seen with sjogren’s syndrome |
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Term
| Primary peristalsis is mediated by what chemical? |
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Definition
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Term
| Secondary peristalsis is activated by what? |
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Definition
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Term
| What function does VIP hormone have in peristalsis? |
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Definition
o Mediates relaxation of wall ahead of food bolus
o Released locally from nerve plexus |
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Term
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Definition
o Inability of the esophagus to relax
o Genetic inherited disorder |
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Term
| Achlasia is usually due to a malformation of what plexus? |
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Definition
| Malformation of myenteric plexus |
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Term
| PSNS controls GI function through release of what chemical? |
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Definition
|
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Term
| Acetylcholine release stimulates what cells to produce what chemical? |
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Definition
| Mass cells/chromafin cells in the stomach |
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Term
| What effects in stomach are seen from vagus nerve stimulation? |
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Definition
o Increases motility
o Increases secretion of HCl and pepsinogen
o Increases secretion of mucus |
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Term
| Stimulation of SNS has what effect in stomach? |
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Definition
o Decreases motility
o Decreases secretion of HCl and pepsin
o Increases mucus production |
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Term
| Secretion of gastrin activates gastrin receptors located where? |
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Definition
| Located in body/fundus of stomach |
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Term
| Stimulation of gastrin receptors has what effects? |
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Definition
| Increase HCl secretion, increase motility, increase pepsin, increase mucus |
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Term
| GIP is produced where in the GI tract? |
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Definition
| Produced in first part of duodenum |
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Term
| What stimulates GIP production? |
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Definition
| Food entering small intestine |
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Term
| What is the effect on stomach from GIP? |
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Definition
| Decreases HCl secretion, decreases motility, decreases pepsin, decreases mucus |
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Term
| What are the phases of stomach movement? |
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Definition
o Phase I: Celiac phase (Psychic phase)
• Get hungry when smell or think of food
• Stimulates secretion of acid and pepsin
o Phase II: Gastric phase
• Primarily from food products
• Presence of food causes local enteric reflexes of stomach initiating mvmt and gastric acid and pepsinogen secretion and stomach stretch |
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Term
| Where is the pacemaker in the stomach located? |
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Definition
| Located at the incisura angularis initially but moves up lesser curve with presence of food in stomach |
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Term
| Describe pacemakers function in stomach emptying |
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Definition
o Pacemaker forms spike potentials on BER waves and initiates a contraction
o Pacemaker moves up lesser curve with food present in stomach
o Each time pacemaker moves up it causes more of stomach to contract
o Food hitting the closed pyloric valve cause food to mix back up with fundus contents |
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Term
|
Definition
| Splitting of bonds in the presence of HCl acid |
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Term
| Where is vomiting center located? |
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Definition
| Chemoreceptor area in brainstem in area of medulla-pontine border |
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Term
| What are events occurring with activation of vomiting center? |
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Definition
1. Hypersalivation
2. Soft palate and uvula elevate
3. Larynx is approximated/glottis closes
4. Esophagus fully dilates via inhibition
5. Cardiac sphincter dilates
6. Strong sudden contraction of diaphragm and abdominal muscles |
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