Shared Flashcard Set

Details

Physiology Week 2
KYCOM Block 8
167
Physiology
Graduate
04/29/2013

Additional Physiology Flashcards

 


 

Cards

Term
what is the name for the smooth muscle of the GI treat, what makes it unique, where is it located
Definition
it is everywher except the upper 1/3 of the esophagus and external anal sphinctor

connected via gap junctions, low resistance, coordinated

2 muscle components
circular: decreases diametes
longitudinal: shortens length
Term
what are the types of contraction for the smooth muscle of the GI tract: mechanism, location
Definition
phasic: contraction followed by relaxation
in esophagus, gastric antrum, SI, and tissues with mixing and propulsion

tonic: constant level of contraction in orad, lower esophagus, ileocecal, intestinal sphinctor
Term
explain what a slow / myogenic wave is
Definition
not action potential, slow wave of oscillating depolarization and repolarization that does not cause contraction (EM below threashold)
Term
if slow waves dont cause contraction, how is there contraction in the smooth muscle of GI
Definition
parasympathetic innervation at the time of plateau of a slow wave gives it enough potential to pass threashold
Term
what is the range of frequencies for slow waves, in what areas is this the slowest and fastest
Definition
3 in stomach to 12 in duodenum waves per minute
Term
how if the speed of the slow waves adjusted
Definition
it isnt, can only modulate product of AP (hormonal or neural) at platau and which adusts strength in contraction, not rate
Term
what is the origin of the slow wave, where is it located, why is it effective
Definition
interstitial cells of cajal in myenteric plexus (between circular and longitudinal muscle)

effective because of spread of waves between low resistance gap junctions
Term
explain the cellular mechanism for slow waves
Definition
depolarization: Ca channels open, Ca moves in
plaeau: membrane potential depolarized all the way until threashold (at this time parasympathetic innervation will do AP)
repolarization: K channels open, K moves out
Term
if there is no parasympathetic input what is the effect of slow waves? what about when there is sympathetic input
Definition
tonic (basal) contraction, sympathetic does nothing so it stays here
Term
when parasympathetic stimulates the slow wave plateau, explain the contraction
Definition
phasic, more AP stronger contraction
Term
what is the function of mastication (5)
Definition
mix food with saliva, reduce size of food particles, enable taste, swallowing, mixing with salivary amalyase to digest carbs
Term
what are the two ways to initiate mastication, how do they work
Definition
• Involuntary: Mechanoreceptors connect to brainstem and make oscillatory pattern of muscle movement
• Voluntary: Can override involuntary chewing at any time
Term
what are the phases of deglutition, are the voluntary or involuntary
Definition
oral: voluntary
pharyngeal: involuntary
esophageal: voluntary
Term
what are the 6 events in the oral phase
Definition
o Tongue voluntarily forces bolus toward pharynx
o Bolus stimulates somatosensory receptors in pharynx
o Vagus and glossopharyngeal nerve send info to medullary swallowing center
o Efferent output to striated muscles of pharynx and upper esophagus stimulated
o Involuntary swallowing reflex initiated
o Lower esophageal sphincter relaxes
Term
what are the 6 events in the pharyngeal phase
Definition
o Soft palate pulls up so food cannot get into nasopharynx (breathing inhibited)
o Epiglottis covers opening to larynx (Adam’s apple)
o larynx moves up against epiglottis to prevent entry into trachea
o Upper esophageal sphincter relaxes
o Peristalsis propels food through
 Lower esophageal sphincter closes when peristalsis arrives
Term
in the esophageal phase, what events are under control of the swallowing reflex
Definition
 Upper esophageal sphincter closes to prevent reflux
 Primary peristaltic wave travels down esophagus
 receptive relaxation
 sphinctor contracts to resting tone as soon as bolus enters
Term
in the esophageal phase, what events are under control of the enteric nervous system, explain it too
Definition
secondary peristaltic wave: clearns remaining food at begining point of distension (initiated by un-cleared food)
Term
what is receptive relaxation, how is it initiated
Definition
• Food approaching opens the lower esophageal sphincter causes orad of stomach relaxation, decreasing the pressure to welcome bolus
• Vagus nerve releases VIP relaxing the areas
Term
explain how peristalsis works
Definition
• As an area closes it creates a high pressure that pushes the bolus
Term
explain the role of intra-thoracic pressure in deglutition, how is this regulated
Definition
 Intra-esophageal pressure is equal to intra-thoracic pressure which is lower than atmospheric and abdominal
 Makes it hard to keep air out of the top and acid out of the bottom of the esophagus
 Upper and lower esophageal sphincters have to take care of this so they are closed unless a bolus is passing
Term
define manometry
Definition
difference between opening and closing of sphincters is a result of the delay of food passage down esophagus
Term
GERD: causes, symptoms, associations
Definition
o Intra-abdominal pressure is increased
o Pregnancy, obesity
o Contents of stomach reflux into esophagus
o Esophageal mucosa damage
Term
what is dysphagia, what are the types
Definition
difficulty swallowing: oropharyngeal, esophageal
Term
what are the causes of oropharyngeal dysphagia
Definition
 Neurological: bulbar palsy (paralysis), pseudo-bulbar palsy, myasthenia gravis (NMJ disorder, weakness)
Term
what are the causes of esophageal dysphagia
Definition
• benign (rings, polyps, peptic ulcer), malignant (carcinoma in esophagus, stomach, extrinsic compression), esophagitis (candidias, inflammation), achalasia (can’t relax)
Term
how can a dysphagia be diagnosed
Definition
• endoscopy
• barium sulfate contrast radiology
• esophageal manometry: catheter into nose to stomach, withdrawal to detect pressure changes
Term
what are the 3 necessities for gastric motility
Definition
o Relaxation of orad to receive bolus
o Contractions to reduce size and mix bolus with secretions to digest
o Gastric emptying and propulsion of chyme into SI
Term
what are the muscles of the stomach
Definition
 Outer longitudinal
 Middle circular
 Inner oblique
Term
what are the regions of the stomach, give their main functions
Definition
 Fundus
 Body: stores food, weak contraction, many oxyntic glands
 Antrum: thick muscle, peristalsis, retropulsion of bolus into antrum
 Pylorus: regulates passage of chyme into duodenum to a small size
Term
what are the regions of the stomach based on motility. what traditional regions do they contain. what is another difference and function
Definition
o Regions Based on motility
 Orad: proximal thin walled. Contains fundus and proximal body
 Caudad: distal thick walled. Strong contractions to mix food and propel it into SI.
Term
explain how receptive relaxation works in the stomach
Definition
o Distension of the lower esophagus by food relaxes the lower esophageal sphincter
o Detected by mechanoreceptors
o Vasovagal reflex: afferent and efferent limbs on vagus nerve via VIP
o Reduces pressure and increases volume of orad of stomach
Term
vagotomy: purpose, procedure, results
Definition
 eliminates receptive relaxation
 cutting of the vagus nerve
 reduces stomach acid secretion
Term
how does mixing and digestion occur in stomach, in what direction
Definition
o Waves of contraction begin at mid body and move distally along caudad increasing in strength and veolcity to pylorus
o Mix food and propel into duodenum
Term
what is retropulsion
Definition
 Wave of contraction closes pylorus so much chyme is propelled back into the stomach for more mixing than into duodenum
Term
where do slow waves occur in stomach, how often
Definition
 In caudad region at 3-5 per minute
Term
what does parasympathetic innervation do to stomach slow waves, what transmitters
Definition
• gastrin and motilin increase frequency of AP and force of wave / contraction
Term
what does sympathetic do to stomach slow waves, what transmitters
Definition
• GIP and secretin decrease frequency of AP and force of contraction
Term
migrating myoelectric complex: 2 functions, locations, regulators, definition, stimulated by, when it happens
Definition
• Moltin causes contractions to occur in 90 minute intervals in fasting
• Regular cycle of waves every 5-10 min initiated by vagal stimulation
• Regulated by VIP, motilin, enkaphalin

• in small intestine and stomach

Functions
o Clear stomach and colon of residue and un-digestible things
o Inhibit colonization of bacteria in the small intestines
Term
gastric emptying: length, what empties faster, requirements for particles, stimulation to end
Definition
o Takes approx. 3 hours
o Liquids and isotonic contents empty faster
o Particles must be 1mm3 or less, retropulsion continues until this is reached
Term
what regulates gastric emptying
Definition
 Fat in duodenum stimulates CCK which slows emptying so fat can digest
 H+ stimulates mucosa of duodenum and enteric nervous system sends info to the stomach via myenteric plexus to slow emptying so there is more time for H+ to be neutralized by pancreas enzymes
Term
what isthe frequency of slow waves in the small intestine parts
Definition
12 in duodenum, 8-9 in ileum
Term
what does parasympathetic and sympathet innervation do to the slow waves of the small intestines. what neurotransmitters
Definition
parasympathetic: increases contraction. cholinergic and some peptidergic fibers (VIP, encephalin, motilin)
Term
explain segmentation in the small intestines, what controls this movement, what is the function
Definition
enteric NS

• mix cyme and expose it to pancreatic enymes
• bolus in intestinal lumen is split by contraction, the section relaxes and bolus comes back together
• produces no forward movement
Term
explain peristaltic contraction in the small intestines, what neurotransmitters are used
Definition
• propel chyme toward large intestines
• contraction occurs behind bolus (orad) and a portion in front of bolus (caudad) relaxes
• neurotransmitters for contraction are Ach, substance P
• neurotransmitters for relaxation are VIP, NO
Term
what is the afferent portion of the vomitting reflex
Definition
 back of throat and GI tract chemoreceptors carry information on vestibular system triggering zone in 4th ventricle (vomiting center in medulla)
Term
what is the efferent portion of the vomitting reflex
Definition
 Reverse peristalsis begins in small intestines
 Stomach and pylorus relaxes
 Forced inspiration to increase abdominal pressure
 Relaxation of lower esophageal sphincter
Term
what movements produce reching
Definition
vomitting reflex with...
 Upper esophageal sphincter remains closed
 Lower esophageal sphincter is opened and gastric contents return to stomach
Term
what are the contents of the large intestine called
Definition
feces
Term
why is there less movement in the large intestines
Definition
• Less myenteric plexus development and vagus innervation t leads to slower movement
Term
what is the function of the bacteria in the large intestines
Definition
Bacteria: Make vitamin K and vitamin B complexes
Term
what is the function of mucous in the large intestines
Definition
• Mucous: holds feces together, alkinity prevents acid attacks to wall
Term
what prevents reflux into the ileum
Definition
ileocecal sphinctor
Term
what types of movements occur in the large intestines
Definition
segmentation contection, mass movement
Term
where does most of the water absorption in the GI occur, what is the consequence of this
Definition
distal colon (can make contents difficult to move)
Term
where does large intestine segmentation occur, how
Definition
o Occur in cecum and proximal colon
o Mix contents in haustra (segments)
Term
how often to mass movements occur, why is this diffiuclt, how does it work
Definition
o Occur in colon 1-3 times per day
o Move contents to rectum where it is stored until defecation
o Water absorption occurs (makes contents more difficult to move)
o Longitudinal muscle layer is teniae coli which contract hastura
Term
what reflex controls defecation, what controls it, how does it work
Definition
 Rectum filles with feces and smooth muscle of rectum contracts, internal anal sphincter relaxes
 External anal sphincter is voluntarily relaxed and smooth muscle of rectum contracts to make pressure (innervated by the pudendal nerve)
Term
what is valsalva, what is the function
Definition
 Expiring against closed glottis
 Can increase intra-abdominal pressure for additional pressure
Term
what happens if there is an urge to defecate and it does not occur
Definition
 Rectum contracts and forces feces back into colon
 Urge to defecate can be over ridden by contraction of the external anal sphinctor
Term
explain the ileocecal reflex
Definition
Distension of ileum causes ileocecal sphincter to relax. Distension of the colon causes ileocecal sphincter to contract
Term
explain the gastroileal reflex
Definition
produces mass movement shortly after a meal due to action of gastrin and extrinsic autonomic nerves
Term
hirschsprung disease: AKA, cause, effect
Definition
o Chronically constricted colon blocks feces which accumulate and distend colon
o Loss of ganglion cells and low VIP
o bad neural crest migration to make auerbach's plexus in part of colon
o most of the time near the anus
Term
IBS: definition, cause
Definition
o Alternating diarrhea and constipation
o Pain and discomfort with unknown etiology (diffuse or localized to the left iliac fossa)
o relieved by defication
o frequent small stools but patient feels emptying is incomplete
o abdomen distended
o painful spasms, constipation, dirrhea, mucous
o related to stress, sedentary
o relieved by exercise
Term
what are the functions of saliva (13)
Definition
o Initial digestion of starch and lipid
o Dilution and buffering of ingested foods
o Lubrication with mucus to aid in movement
o Hydrating, cleansing, maintenance of mucus
o Antifungal, antibacterial
o Immunity mediator
o Enable swallowing, tasting, and speech articulation
Term
how much saliva is secreted per day
Definition
1 L
Term
where are glands with serous cells located, what do they secrete
Definition
 In Parotid and lingual gland
 secrete water, ions and enzymes
Term
where are glands with mucous cells located, what do they secrete
Definition
 Secrete Glycoproteins, palatine
 In pos-lingual and labial buccal gland
Term
where are glands with serous and mucous cells (mixed) located? which type of cells do these glands have more of? what is the mixed secretion called
Definition
 Submaxillary (more mucous) and submandibular glands (more serous)
 secrete aqueous fluid and mucus (glycoproteins)
Term
list the branches of the gland in order begining with the most inner part. what cells are in each part
Definition
acinus: acinar cells and myoepithelial cells

intercalated duct: myoepithelial cells

striated duct: ductal cells
Term
what do acinar cells do, what stimulates them
Definition
• make initial saliva
• Innervation is parasympathetic (dominant) and sympathetic both stimulate secretion
Term
what do myoepithelial cells do what stimulates them
Definition
eject saliva via neural input
Term
what do ductal cells do, what stimulates them
Definition
• modify initial saliva into final saliva by altering enzymes and electrolytes
• Innervation is sympathetic and parasympathetic (dominant) both stimulate secretion
Term
what substances does saliva have in it, what is the tonicity, what are the relative ion concentrations
Definition
 Water, lingual lipase, kallikerin, mucus, a-amalyase
 Hypotonic to plasma
 More K and bicarbonate, low Na and Cl
Term
what is in initial saliva, give a brief function of each
Definition
o water, ions, enzymes, mucus
o a-amalyase: begins digestion of carbs
o lingual lipase: begins digestion of lipids
o mucin glycoproteins: lubricant
o IgA
o Kallikerin: cleaves kininogen to bradykinin which is a vasodilator helping the high salivary blood flow
Term
what anatomical feature allows for an increase in saliva production
Definition
high blood flow
Term
what pumps and channels do ductal cells use to modify saliva. what is the overall movement
Definition
• Luminal side: Na/H exchanger, Cl/bicarb exchanger, H/K exchanger
• Blood side: Na/K ATPase pump, Cl channel into blood
• Overall secretion of K and bicarbonate and absorption of Na and Cl
• Net is absorption
Term
how do the ductal cells make saliva hypotonic to plasma
Definition
they are not permeable to water so pumps are able to create this
Term
where is the highest and lowest flow rate of saliva, what is the rate, what conditions are needed to make these rates
Definition
o Highest rate: 4 mL/min. Final saliva closely resembles plasma, there was less time to modify saliva
o Lowest rate: < 1mL/min. Final saliva is not like plasma, it has lower NaCl and higher K
Term
what is the main determinant of salivary flow rate
Definition
changes in ionic composition
Term
explain the changes of the flow rate of bicarbonate in saliva, what makes it change
Definition
o Bicarbonate is lowest at high flow rates and highest at high because it is selectively secreted when saliva production is stimulated by the autonomic nervous system
Term
how does the parasmpathetic nervous system control the secretion of saliva: CN, neurotransmitter, where are receptors, what mechanism causes increased secretion
Definition
 CN VII and IX release ACh which acts on muscarinic receptors of acinar and ductal cells to produce IP3 which increases Ca and causes saliva secretion
Term
how does the sympathetic nervous system regulate secretion of saliva: neurotransmitters, receptors, on what cells, what mechanism
Definition
 T1-T3 preganglionics synapse at the superior cervical ganglion
 Postganglionics release norepinephrine which acts on B-adrenergic receptors on acinar and ductal cells signaling adenylyl cyclase and cAMP to increase IP3 and Ca
Term
what are the components of gastric juice
Definition
 HCl and pepsinogen: initiate protein digestion
 Intrinsic factor: a mucoprotein required to absorption of B12 in ileum (only essential component)
 Mucus: prevents mucosa from being corroded by HCl and lubricates
Term
what are the types of glands in the body of the stomach, what types of cells are they in, anatomically where are these glands in the mucosa
Definition
oxyntic glands in cheif and parietal cells
 secrete contents into openings, or pits, lined with epithelial cells then mucous neck cells, parietial (oxyntic cells), and chief (peptic) cells on the bottom
Term
what do chief cells secrete, what are they controlled by, what is the fate of the secretion
Definition
• Secreted pepsinogen which is converted to pepsin via HCl secreted by parietal cells
• Pepsin breaks down proteins
• Controlled by vagal stimulation so it only releases pepsinogen when pH is low enough to convert it to pepsin
Term
what are parietal cells stimulated by, what precursor or pre-step do they need to function
Definition
• Stimulated by vagus and secrete ACh
o CO2 from aerobic respiration and H2O join via carbonic anhydrase to make H2CO3 which breaks into H+ and HCO3-
Term
what transporters and channels are in a parietal cell
Definition
• Luminal side
o H+/K+ ATPase: secreted H into the lumen
o Cl channel allows Cl into lumen

• Blood side
o Na/K ATPase reabsorbs Na into blood
o HCO3- /K exchanger reabsorbs HCO3- into blood
Term
what does omeprazole do
Definition
inhibits H/K ATPase in luminal side of parietal cells to treat ulcers by reducing H
Term
what is alkaline tide
Definition
high pH in gastric venous blood after a meal caused by bicarbonate via bicarbonate/K exchanger that reabsorbs bicarbonate into the blood on the blood side of parietal cells
Term
what secretes intrinsic factor, what does a decrease in this cause
Definition
parietal cells secrete, decrease causes pernnicious anemia
Term
how does ACh regulate gastric secretion: receptor, mechanism in cell
Definition
 Released via vagus to M3 receptors in parietal cells
 Secondary messenger activating phospholipase C liberating DAG and IP3/Ca, Ca and DAG activate protein kinase, Cells secrete H
Term
what does aropine do
Definition
block M3 receptors in parietal cells from ACh stimulation
Term
how does histamine regulate gastric secretion: where is it released from, what repceptors, what mechanism in the cell
Definition
 Released from enterochromaggin like cells (ECL) via paracrine to parietal cells
 H2 receptors stimulate cAMP, adenylyl cyclase, PKA
 Secretion of H by parietal cell
Term
what does cimetidine do
Definition
blocks H2 receptors stopping histamine stimulation of gastric secretion
Term
how is the rate of gastric secretion regulated
Definition
 Regulated by ACh, histamine, and gastrin independent and together (potentiation: combined response greater)
Term
what is potentiation, what challenges does this create, give an example
Definition
 potentiation: combined response greater)
 Potentiation makes it difficult for drugs to control H secretion
• Example: Cimetidine blocks histamine and histamine potentiated effects of ACh and gastrin causing greater effect
Term
what glands are in the antrum of the stomach, in what cells, what do they secrete
Definition
Pyloric glands:
: Smaller than oxyntic but with deeper pits
 G cells: secrete gastrin into circulation
 Mucous cells: secrete bicarb, mucous, and pepsinogen
Term
what are the stages of secretion in stomach
Definition
cephalic, gastric, intestinal, inhibition
Term
what occurs in the cephalic phase of stomach secretion
Definition
 Smell, tasting, chewing, swallowing, and conditioned reflexes in anticipation stimulate
 30% of HCl secretion in response to a meal
Term
how is the cephalic stage of secretion initiated / stimulated
Definition
 Direct stimulation of parietal cell by vagus nerve which releases ACh
 Indirect stimulation of parietal cell by gastrin via GRP released by vagus nerve onto G cells
 Local reflexes and vagal stimulation stimulate for chielf cells to secrete pepsinogen
Term
gastric stage of stomach secretion: what is secreted, what stimulates it
Definition
 60% of HCl secretion in response to a meal
 Distension of the stomach causes vagus to stimulate directly and indirectly
 Distension of the stomach antrum initiates local reflexes to stimulate gastrin release
 AA and peptides act on G cells to cause gastrin release
Term
what is secreted in the intestinal stage of gastric secretion, what is it mediated by
Definition
 10% of HCl secretion
 Mediated by protein products of digestion
Term
how is secretion in the stomach inhibited
Definition
 HCl is no longer needed to activate pepsinogen so decreased pH stimulates. Food was buffering H but not its done and it becomes acidic
 Somatostatin: Direct pathway: binds to parietal cells via G protein stopping adenylyl cyclase antagonizing histamine. Indirect pathway: inhibit histamine and gastrin release
 Prostaglandins: Antagonize histamine actions on parietal cells
Term
describe the location of the pancreas
Definition
LUQ, retroperitoneal, tail touches spleen, sits in curve of duodenum
Term
what are the endocrine cells of the pancreas, also tell each type and what they secrete
Definition
Islets of langerhan cells:
 Beta cells: secrete insulin to decrease blood sugar
 Alpha cells: secrete glucagon to increase blood sugar
 Delta cells: secrete somatostatin
 F/PP cells: secrete polypeptides
Term
how much fluid does the axocrine part of the pancreas secrete, what are the two components and their general functions
Definition
o Secrete 1 L / day into the duodenum
o Aqueous component: Bicarbonate neutralizes H from stomach
o Enzymatic component digests carbs, proteins, lipids
Term
what cells does the acinus of the pancreas have, what do they secrete
Definition
acinar cells, secrete digestive enzymes stored in zymogen granules
Term
what cells are in the ducts of the pancreas, what do they do
Definition
 Ductal cells: extend into centroacinar cells into acinus. modify secretions of aqueous component
 Centroacinar cells: Secrete bicarbonate, extend into the central acinar portion of the duct
Term
explain the parasympathetic and sympathetic innervation of the pancreas
Definition
o Sympathetic: Postganglionic cells come from superior mesenteric and celiac plexuses. Inhibits secretion
o Parasympathetic: Synapse in enteric nervous system. Stimulates secretion
Term
enzymes of the pancreas: which ones are secreted active, what ones are secreted inactibe, where are they made
Definition
 Pancreatic amalyase and lipases are secreted as active enzymes
 Pancreatic proteases are secreted as inactive. Pancreas also secretes trypsinogen which turns into trypsin to activate
 Made in RER of acinar cells, golgi put them into vacuoles, concentrated into zymogen granules, stored until stimulated
Term
what are the contents of pancreatic juice
Definition
• Isotonic, Na, K, Cl, bicarb
• Cl and bicarbonate concentrations vary with pancreatic flow
Term
how is pancreatic juice formed in general
Definition
 Centroacinar and ductal cells make isotonic secretion
 Ductal cells modify aqueous component
Term
how do pancreatic ductal cells modify pancreatic juice: transporters on each side, net change
Definition
• Apical side: Cl/bicarbonate exchanger puts Cl into cell
• Basal side: Na/H exchanger puts H into blood, Na/K ATPase puts Na into blood
• CO2 + H2O  H2CO3H+ + HCO3-
o overall: Secretion of bicarbonate into pancreatic duct and absorption of H acidifying pancreatic blood
Term
how is the rate of pancreatic secretions regulated: when is it the highest, lowest, what is affected by the change in rate
Definition
o Change in rate only affects Cl/bicarbonate
o High rate: Bicarbonate is high in pancreatic juice. Cl is low
o Low rate: Bicarbonate is low in pancreatic juice
Term
what are the phases of secretion in the pancreas
Definition
cephalic, gastric, intestinal
Term
cephalic phase of secretion in the pancreas: initiated by, nerves, secreted
Definition
 Initiated by smell, taste, and conditioning
 Mediated by vagus nerve
 Produces mostly enzymes
Term
gastric phase of secretion in the pancreas: initiated by, nerve, produces
Definition
 Initiated by smell, taste, and conditioning
 Mediated by vagus nerve
 Produces mostly enzymes
Term
intestinal phase of secretion in pancreas: stimulation, what cels stimulated
Definition
enzymes and pancreatic secretion stimulate acinar cells and ductal cells
Term
what do acinar cells do when stimulated in pancreatic secretion: what stimulates them, nerves, secretions
Definition
• I cells stimulated by AA, peptides, and FA release of CCK, phenylalanine, methionine, and tryptophan. CCK stimulates CCKA receptors
• ACh stimulates muscarinic receptors and stimulates CCK via vasovagal reflexes
Term
ductal cells in pancreatic secretion: what stimulats them, what do they release
Definition
o Release by S cells in duodenum in response to H in lumen
o Stimulates bicarbonate secretion to neutralize to pancreatic lipases can work
o Potentiated by CCK and ACh
Term
what are the parts of bile and general function
Definition
o Emulsify lipids and put into a micelle
o Bile salts, bile pigments, lipids, ions, water
Term
what is the anatomical transition from the foregut to the midgut, where is it located
Definition
o Amoulla of vatar (hepatopancreatic ampulla) at pancreatic and common bile duct junction
Term
what are bile salts made of
Definition
bile acids, glycine, taurine, cholesterol, phospholipids, bile pigments, electrolytes, water
Term
what are bile acids made of, how is it made
Definition
• Primary bile acids (cholic and cheodeoxycholic acid) are dehydroxylated by intestinal bacteria in intestine to make secondary bile acids (deoxycholic and lighocholic acid)
• Cholic > chenodeoxycholic > deoxycholic > lithocolic
Term
what is conjugation, where does it occur, what is the function
Definition
• Occurs in the liver
• Different acid and glycine or taurine combination allows for 3 different bile salts (glycoholic or taurocholic acid)
o function: To more bile acids more water soluble. pK of 1-4 so they deionize and are soluble
Term
bile salts are conjugated to be amphipathic, what does this allow them do to, how does this contribute to the functions of the GI tract
Definition
o at oil-water interface hydrophilic part dissolves in aqueous phase and hydrophobic part dissolves in oil phase
o allows lipids to be soluble (emulsify) because negative charges surround lipid increasing SA for digestion
o forms micelles around product of lipid digestion
Term
bile pigments / bilirubin: how does this contribute to colors of thigns in the GI system, what is the process of coversion of molecules to create these colors
Definition
 yellow color pigment of Hb degradation by reticuloendothelial system
 carried in blood on albumin
 conjugates with glucronic acid in liver making bilirubin glucuronide
 converted to bilirubin and to urobilinogen by intestinal bacteria
 some is circulated back into liver, some is oxidized to urobilin and stercobilin (makes poo dark)
Term
how does cholesterol and phospholipids get into bile, what happens to it once secreted
Definition
 secreted into bile by hepatocytes
 inside micelles with products of lipid digestion
 phospholipids are amphipathic aiding in micelle formation
Term
what happens to the electrohytes and water in the bile ducts
Definition
 secretin stimulates ion and water secretion in bile ducts
Term
what do hepatocytes secrete
Definition
bile salts, cholesterol, phospholipids, bile pigments, ions, and water
Term
what are the functions of the gallbladder
Definition
• Stores bile
• concentrates bile salts: absorbing water and ions by epithelial cells in isosmotic fashion. organic components become concentrated
• ejects bile into duodenum: within 30 min of meal. I cell sense Fa, AA, and peptides and release CCK. CCK contracts gallbladder and relaxes sphincter of Oddi. Bile is ejected in spurts
Term
how is bile recycled
Definition
o Enterohepatic circulation: In terminal part of ileum bile (max digestion) salts are transported to portal blood via Na/bile co-transporter. Portal blood carries bile back to liver. Liver extracts bile salts and adds them to hepatic bile pool
Term
how much bile is lost, where
Definition
 In feces about 600 mg/day
Term
how is bile secretion regulated
Definition
o Bile salts recirculating to the liver stop the rate limiting step in their production, cholesterol 7a-hydroxylase via negative feedback
o When less is recirculated, more bile salts are made
o Choleretic effect: recirculation of bile salts stimulates biliary secretion
Term
what is candidias
Definition
fungal infection in the mouth
Term
what is orallichen planus
Definition
affects mucosa
Term
what is burning mouth syndrome
Definition
glossodyna: normal appearing mucosa with burning sensation
Term
what is an aphthous ulcer
Definition
canker sore, mouth ulcer
Term
what is a dental carie
Definition
tooth decay due to bacterial infection
Term
what normally protects the lumen of the stomach
Definition
 Mucous neck glands secrete mucous
 Gastric epithelial cells secrete bicarbonate which traps in mucous and neutralizes
 Prostaglandins, mucosal blood flow, growth factors
Term
what are the causes of peptic ulcer disease
Definition
 Lesion of gastric or duodenal mucosa cause by erosion via H and pepsin or H. pylori, NSAIDS, stress, smoking, and alcohol, hyperthyroidism (high Ca stimulates secretion), sollinger ellisons syndrome, ASA, caffiene stimulates gastric acid secretion
 Loss of mucous , excessive H or pepsin secretion, or both
Term
gastric ulcer causes
Definition
 Usually due to mucous barrier issue
 Major cause is H. plyori often in antrum releasing cytotoxins (cagA toxin) breaking down barrier and colonizing with the urease (converts urea to NH3 making it alkaline)
Term
gastric ulcer disease, how do diagnose
Definition
 Diagnosis: drink 13C-urea which is converted to 13CO2 and NH3 in stomach. 13CO2 is absorbed into blood, expired by lungs, and measured in breath test. Secretion of H+ is low because some is secreting into mucosa
Term
duodenal ulcer: causes
Definition
 More common because H+ secretion is higher and can overwhelm bicarbonate
 Can also be caused by H.pylori indirectly because. they inhibit somatostatin secretion from D cells in antrum increasing gastrin secretion and H+. they infect duodenum and inhibit bicarbonate secretion
 gastrin levels may be normal but release in response to a meal is increased

genetic: no secretion of O blood group antigens into saliva and gastric juice have increased risk
Term
zollinger ellison syndrome (gastrinoma): causes, effect, symptoms, treatment
Definition
 highest H+ levels
 tumor, usually in pancreas, secretes lots of gastrin
 increased H+ secretion in parietal cells and increased parietal cell mass
 overpowers bicarbonate and erodes
 steatirrhea because pH deactivates pancreatic lipases
 not feedback inhibited by H+
 treatment: inhibit H+ secretion (cimetidine, omeptrazole), surgical tumor removal
Term
how can you diagnose a peptic ulcer
Definition
 urease breath test: drink 13C urea. converted to 13CO2 and NH3 in stomach. 13CO2 is absorbed into the blood and expired into the lungs and measured. Gastric ulcers give lower H than normal because H secreted leaks into damaged mucosa
 Endoscopy: Barium meal with contrast x-ray biopsy to show bacterial or malignancy
Term
what medications are used for peptic ulcers
Definition
 H. pylori cause: proton pump inhibitor like omeprazole (Prilosec)
 Non H. pylori cause: proton pump inhibitors
 Cimetidine (tagmet), famotidine (Pepcid), ranitidine(zantac), antacid
histamine H2 antagonist like cimetidien, ranitidine, famotidine, nizatitine inhibit parietal cells
prostaglandin E analouge (misprostol) inhibits gastric acid secretion by inhibiting cAMP in parietal cells
surgery if there are lots of complications
Term
decreased intrinsic factor: cause, why its bad
Definition
o Caused by decreased RBC, removal of stomach
o The only essential secretion
Term
ileal resection: cause, symptoms
Definition
o Removal of ileum
o Recirculation of bile salt is interrupted and much is excreted
o Synthesis of new bile salts is very stimulated but cannot keep up
o Impaired lipid absorption
o Steatorrhea: increased fat in stool
Term
what is bile acid diarrhea, what treats it
Definition
o High bile acids in the intestinal lumen stimulates cAMP dependent Cl secretion in colon epithelial cells. Na and water follow Cl into lumen causing secretory diarrhea
o Cholestyramine treats
Term
how does cholestyramine work
Definition
 Treatment bunds bile acids in the colon so they do not stimulate Cl secretion
 Does not prevent steatorrhea
 Plasma cholesterol is converted to bile acids lowering plasma cholesterol
• Also used for hypercholesterolemia
Term
what are the diseases of the exocrine pancreas
Definition
cystic fibrosis, acute pancreatitis, chronic pancreatitis, carcinoma of the pancreas
Term
cystic fibrosis: cause, effect, symptoms
Definition
 Most common lethal genetic disease
 Mucosa secretions are thick and block airway and pancreatic duct
 Recurrent pulmonary infection, pancreatic insufficiency, high NaCl in sweat, transmembrane regulator (CFTR) defective, pancreatic duct may have cyst, malabsorption, duct dilation
 CF gene on chromome 7 mutated
Term
acute pancreatitis causes
Definition
 Inflammation of the pancreas, almost always associated with acinar cell injury
• Metabolic: alcohol, hyperlipoproteinemia, hyperclacemia, drugs
• Mechanical: gall stones, traumatic periperative injury
• Vascular: shock, atherombolism
Term
acute pancreatitis pathology / issues associated
Definition
• Protrolytic destruction of pancreatic substance
• Necrosis of vessels and interstitial hemorrhage
• Fat necrosis by lipolytic enzymes
• Associated acute inflammatory reaction
Term
chronic pancreattis: cause, effects
Definition
 Protein hyper secretion (acinar cells)
 Protein precipitation forming ductal plugs enlarge to form aggregates
Term
carcinoma of the pancreas: cause, definition, diagnosis, prognosis
Definition
 Malignant epithelial neoplasm of exocrine pancreas
 Causes: unknown, frequent in smokers
 Usually silent until first symptom, obstructive jaundice
 1 year survival
Term
what is megacolon
Definition
a fodm of hirschspring disease that affects people with parkinsonism diabetic neuropathy
Term
constipation: causes, symptoms, treatment
Definition
low fiber in sedentary persons
irregulat defecation
irrational use of laxatives supressing natural reflexes
treatment: increase fiber, walking, suppositories
Term
chagas: how is it aquired
Definition
cause vby trypanosome cruzi a parasite that causes african sleeping sickness
spread by bite from reduvid bugs
Term
how is the lumen protected
Definition
mucous neck glands
gastric epithelial cells secrete bicarbonate trapped in mucous
prostaglandins, mucosal blood flow, growth factors
Term
symptoms of PUD
Definition
pain after a meal, worken up with epigastric pain, bleeding from ulcers, uper GI bleeding, hematemesis (vomitting blood or clots), melena (dark, tarry stool, shiny, sticky, foul smelling)
Term
gastritis: definition, classifications, symptoms
Definition
lining of stomach becomes inflammed or swollen

acute, erosive, chronic, non-erosive

symptoms: loss of appetite, nausea, vomiting, pain in upper abdomen, pernicioous anemia
Term
gastritis: causes
Definition
alcohol, drugs, (corticosteroids, NSAIDS, ASA)

main cause in antrum: H. pylori leading to loss of parietal cells (achlorhydria), decreased HCl and intrinsic factor
Term
autoimmine / pan gastritis: cause, risks
Definition
autoantibodies to parietal cells

vitamin b12 not absorbed in ileum due to lack of intrinsic factor, pernicious anemia
Term
what is a risk of long term treatment with acid supression drugs
Definition
mucosal hypertrophy and further rise in acid production with a higher ulcer recurrance rate
Term
what protects the esophagus from the GI mucosa
Definition
clearance mechanisms (UES, LES)

mucosal integrity

LES compliance

gastric emptying
Supporting users have an ad free experience!