Term
| What are epithelial cells? |
|
Definition
| cells specialized in different parts of the GI tract for secretion and absorption. |
|
|
Term
|
Definition
| contration causes a change in the surface area for secretion or absorption |
|
|
Term
|
Definition
| contraction causes a decrease in diameter of the lumen of the Gi tract |
|
|
Term
|
Definition
| contraction causes shortening of a segment of the Gi tract |
|
|
Term
| submucosal plexus and myenteric plexus |
|
Definition
| comprise the enteric nervous sstem of the Gi tract. integrate and coordinate the motility, secretory, and endocrine functions of the gi tract |
|
|
Term
| Extrinsic innervation consist of..... |
|
Definition
| parasympathetic and sympathetic nervous systems |
|
|
Term
|
Definition
| carry information from the brain stem and spinal cord to the GI Tract. |
|
|
Term
|
Definition
| carry sensory information from chemoreceptors and mechanoreceptors in the Gi tract to the brain stem and spinal cord. |
|
|
Term
| parasympathetic nervous system is |
|
Definition
| excitatory on the functions of GI tract, carried via the vagus and pelvic nerves. |
|
|
Term
| preganglionic parasympathetic fibers synapse in the myenteric and submucosal plexuses |
|
Definition
|
|
Term
|
Definition
| in the ganglio of the plexuses then send information to the smooth m., secretory cells, and endocrine cells of the GI tract |
|
|
Term
| the vagus nerve innervates |
|
Definition
| esophagus, stomach, pancreas, and upper large intestine |
|
|
Term
|
Definition
| reflexes in which both afferent and efferent pathways are contained in the vagus nerve |
|
|
Term
|
Definition
| lower large intestine, rectum, and anus |
|
|
Term
| sympathetic nervous system is |
|
Definition
| inhibitory on GI functions |
|
|
Term
| fibers in the sympathetic nervous system originate from |
|
Definition
|
|
Term
| preganglionic sympathetic cholinergic fibers synapse in |
|
Definition
|
|
Term
| postganglionic sympathetic adrenergic fibers leave |
|
Definition
| prevertebral ganglia and synapse in the myenteric and submucosal plexus |
|
|
Term
| cell bodies in ganglia of plexuses send information to |
|
Definition
| smooth m., secretory cells, and endocrine cells of the GI tract |
|
|
Term
| Intrinsic innervation consist of |
|
Definition
|
|
Term
| what does intrinsic innervation do? |
|
Definition
| coordinate and relay information from the parasympathetic and sympathetic nervous systems to GI tract |
|
|
Term
| How does the intrinsic innervation relay information? |
|
Definition
|
|
Term
| what does the intrinsic innervation control? |
|
Definition
| most functions of the GI tract, especially motility and secretion |
|
|
Term
|
Definition
aka Auerback's plexus
primarily controls the motility of the GI smooth m. |
|
|
Term
|
Definition
aka Meissner's plexus
primarily controls secretion and blood flow
recieves sensory information from chemoreceptors and mechanoreceptors in the GI tract |
|
|
Term
| four official GI hormones are |
|
Definition
| gastrin, CCK, secretin, GIP |
|
|
Term
|
Definition
contains 17 a.a.
secreted in response to a meal
all biologic activity resides in the 4 C-terminal a.a. |
|
|
Term
|
Definition
|
|
Term
|
Definition
increases H+ secretion by gastric parietal cells
stimulates growth of gastric mucosa by stimulation synthesis of RNA and new protein. |
|
|
Term
| what do patients with gastrin-secreting tumors have? |
|
Definition
| hypertrophy and hyperplasia of gastric mucosa |
|
|
Term
| where is gastrin secreted from |
|
Definition
| g cells of the gastric antrum |
|
|
Term
| stimuli for gastrin secretion |
|
Definition
in response to a meal
small peptides and a.a. in the lumen of the stomach
distention of stomach
vagal stimulation mediated by GRP |
|
|
Term
| most potent stimuli for gastrin secretion are |
|
Definition
| phenylalanine and tryptophan |
|
|
Term
| what does atropine do to vagal stimulation |
|
Definition
| nothing, does not block it because the mediator fo the vagal effect is GRP not ACh |
|
|
Term
| inhibition of gastrin secretion by |
|
Definition
| H+ in the lumen of the stomach and stomatostatin |
|
|
Term
| what is zollinger-ellison syndrome? |
|
Definition
gastrinoma
occurs when gastrin is secreted by non-B-cell tumors of the pancreas |
|
|
Term
|
Definition
contains 33 a.a.
homologous to gastrin
five C-terminal a.a. are same in CCK and gastrin
biology activity resides in those five ^
has gastrin like activity |
|
|
Term
|
Definition
Stimulates contraction of the gall bladder
causes relaxation of the sphincter of oddi for secretion of bile
stimulates pancreatic enzyme secretion
potentiates secretin-induced stimulation of pancreatic bicard secretion
stimulates growth of exocrine pancreas
inhibits gastric emptying |
|
|
Term
| what does meals with fat do? |
|
Definition
| stimulate secretion of CCK --> slows gastric emptying to allow more time for intestinal digestion and absorption |
|
|
Term
| where is CCK released from? |
|
Definition
| I cells of the duodenal and jejunal mucosa |
|
|
Term
| what stimulates the release of CCK? |
|
Definition
small peptides and a.a.
fatty acids and monoglycerides |
|
|
Term
| why does triglycerides not stimulate the release of CCK? |
|
Definition
| They cannot cross intestinal cell membrane |
|
|
Term
|
Definition
contains 27 a.a.
is homologous to glucagon
all a.a. are required for biologic activity |
|
|
Term
|
Definition
reduce the amount of H+ in the lumen of the small intestine by:
1. stimulate pancreatic bicarb secretion and increase growth of exocrine pancreas
2. stimulate bicarb and h2o secretion by the liver and increases bile production
3. inhibits H+ secretion by gastric parietal cells |
|
|
Term
|
Definition
|
|
Term
| what stimulates the release of secretin? |
|
Definition
H+ in lumen of duodenum
fatty acids in the lumen of the duodenum |
|
|
Term
|
Definition
contain 42 a.a.
homologous to secretin and glucagon |
|
|
Term
|
Definition
stimulates insulin release
inhibits H+ secretion by gastric parietal cells |
|
|
Term
| what happens in the presence of an oral glucose load |
|
Definition
| GIP causes release of insulin from pancrea. |
|
|
Term
|
Definition
|
|
Term
| Stimuli for the release of GIP |
|
Definition
release in response to fat, protein, and carbs
stimulated by fatty acids, a.a., and orally admistered glucose. |
|
|
Term
|
Definition
are released from endocrine cells
diffuse over short distances to act on target cells
consist of somatostatin and histamine |
|
|
Term
| somatostatin is secreted by? |
|
Definition
| cells throughout the GI tract in response to H+ in lumen |
|
|
Term
| what is somatostatin inhibited by? |
|
Definition
|
|
Term
| what does somatostatin do? |
|
Definition
| inhibits release of all GI hormones and gastric H+ secretion |
|
|
Term
|
Definition
| mast cells of gastric mucosa |
|
|
Term
|
Definition
| increases gastric H+ secretion directly and by potentiating the effects of gastrin and vagal stimulation |
|
|
Term
|
Definition
| symthesized in neurons of GI tract, moved by axonal transport down to the axon and released by action potentials in the nerves. diffuses across synaptic cleft to target cell |
|
|
Term
| what are the GI neurocrines |
|
Definition
| VIP, GRP, and enkephalins |
|
|
Term
|
Definition
| contains 28 a.a. and homologous to secretin |
|
|
Term
|
Definition
| neurons in the mucosa and smooth m. of GI tract |
|
|
Term
|
Definition
produces relxation of GI smooth m. including LES
stimulates pancreatic bicarb secretion
inhibits gastric H+ secretion (like secretin) |
|
|
Term
|
Definition
| pancreatic islet cell tumors |
|
|
Term
|
Definition
| vagus nerves that innervate G cells |
|
|
Term
|
Definition
| stimulate gastrin release from G cells |
|
|
Term
| Enkephalins are secreted from |
|
Definition
| nerves in the mucosa and smooth m. of GI tract |
|
|
Term
| what does enkephalins do? |
|
Definition
stimulate contraction of GI smooth m. particularly LES, pyloric and ileocecal spincter
AND
inhibit intestinal secretion of fluid and electrolytes.` |
|
|
Term
| which part of the GI tract is striated muscle? |
|
Definition
| pharynx, upper one-third of the esophagus, and external anal sphincter |
|
|
Term
| contractile tissue of the GI tract is mainly |
|
Definition
|
|
Term
| depolarization of circular muscle leads to |
|
Definition
| contraction of a ring of smooth m. and a decrease in diamenter of the that segment |
|
|
Term
| depolarization of longitundinal m. leads to |
|
Definition
| contraction in the longitudinal direction and decrease in length of that segment |
|
|
Term
| phasic contractions occur in |
|
Definition
| esophagus, gastric antrum, and small intesting, which contract and relax periodically |
|
|
Term
| tonic contractions occur in |
|
Definition
| lower esophageal sphincter, orad stomach, and ileocecal and internal anal sphincters |
|
|
Term
|
Definition
oscillating membrane potentials inherent to smooth m.
occurs spontaneously |
|
|
Term
| where do slow waves originate? |
|
Definition
| in the intersitital cells of Cajal, which serve as the pacemakers for GI smooth m. |
|
|
Term
|
Definition
|
|
Term
| mechanism for slow wave production |
|
Definition
1. cyclic opening of Ca2+ channels (depolarization)
2. Followed by K+ channels opening (repolarization)
3. membrane potential of smooth muscle cells closer to threshold --> increases porbablity that action potentials will occur
4. action potentials initiate contraction of the smooth m. cells |
|
|
Term
| frequency of slow waves is not influenced by |
|
Definition
|
|
Term
| frequency of slow waves sets |
|
Definition
| the maximum frequency of contraction for each part of the GI tract |
|
|
Term
| where is the frequency of slow waves lowest at? |
|
Definition
|
|
Term
| where is the frequency of slow waves highest at? |
|
Definition
|
|
Term
|
Definition
lubricates food by mixing it with saliva
decreases the size of food particles to facilitate swallowing and to begin the digestive process |
|
|
Term
| where is swallowing reflex coordinated at? |
|
Definition
|
|
Term
| what fibers carry information between the GI tract and the medulla? |
|
Definition
| vagus and glossopharyngeal nerves |
|
|
Term
| sequence of events involved in swallowing |
|
Definition
1. nasopharynx closes and at the same time breathing is inhibited
2. laryngeal m. contract to close the glottis and elevate the larynx
3. peristalsis begins in the pharynx to propel the food bolus toward the esophagus. at the same time, UES relaxes to permit the food bolus to enter the esophagus. |
|
|
Term
|
Definition
| propels the swallowed food into the stomach |
|
|
Term
| what is the pressure in the esophagus? |
|
Definition
| intraesophageal pressure equals thoracic pressure --> which is lower than atmospheric pressure. |
|
|
Term
| sequence of events for the movement of food into and down the esophagus |
|
Definition
1. UES relaxes to permit swallowed food to enter the esophagus
2. UES then contracts so food will not reflux into pharynx.
3. primary peristaltic contraction creates an area of high pressure behind the food bolus. peristaltic contraction and gravity moves food down.
4. secondary peristaltic contraction clears esophagus of any remaining food.
5. LES relaxes (vagally mediated by VIP)
6. orad of stomach relaxes so food can enter |
|
|
Term
| Gastroesophageal reflux occurs when? |
|
Definition
|
|
Term
|
Definition
| LES does not relax during swallowing and food accumulates in esophagus |
|
|
Term
|
Definition
fundus and proximal body
contains oxyntic glands
responsible for receiving ingested meal |
|
|
Term
| caudad region of stomach = |
|
Definition
antrum and distal body
responsible for contractions that mix food and propel it into the duodenum |
|
|
Term
|
Definition
is a vagovagal relex that is initiated by distention of stomach and is abolished by vagotomy
orad region of the stomach relaxes to accommodate the injested meal
CCK is involved. it increases the distensibility of the orad stomach |
|
|
Term
| gastric contractions are increased and decreased by what? |
|
Definition
| vagal stimulation and sympathetic stimulation respectively |
|
|
Term
| what mediates the migrating myoelectric complex? |
|
Definition
|
|
Term
| Rate of gastric emptying is fastes when stomach contents is |
|
Definition
|
|
Term
| what inhibits gastric emptying |
|
Definition
| fat by stimulating the release of CCK |
|
|
Term
| What in the duodenum inhibits gastric emptying? |
|
Definition
| H+ via direct neural reflexes |
|
|
Term
| segmentation contractions |
|
Definition
mix the intestinal contents
causes a back and forth movement that causes mixing iwthout any net forward movement of chyme |
|
|
Term
|
Definition
highly coordinated
propel the chyme through small intestine
coordinated by the enteric nervous system |
|
|
Term
|
Definition
| mediated by extrinsic ANS and gastrin |
|
|
Term
| sequence of events for defecation |
|
Definition
1. rectum fills with fecal material, contracts. Internal anal sphincter relaxes (rectosphincteric reflex)
2. ready to defecate, external anal sphincter is relaxed. smooth m of rectum contracts - POOP |
|
|
Term
|
Definition
| intra-abdominal pressure is increased by expiring against a closed glottis |
|
|
Term
|
Definition
presence of food in the stomach increases the motility of the colon and increases the frequency of mass movements.
has a rapid parasympathetic component that is initaiated by stretching of the stomach
slower, hormal component is mediated by CCK and gastrin |
|
|
Term
|
Definition
| increased segmentation contraction |
|
|
Term
|
Definition
| decreased segmentation contraction |
|
|
Term
|
Definition
megacolon
absence of colonic enteric nervous system, results in constriction of invovled segment, marked dilatation and accumulation of intestinal contents proximal to the constriction and severe constipation |
|
|
Term
|
Definition
| UES remains closed so gastric contents can't go back into esophagus |
|
|
Term
| vomiting center in medulla is stimulated by |
|
Definition
| tickling the back of the throat, gastric distention, and vestibular stimulation |
|
|
Term
| chemoreceptor trigger zone is activated by |
|
Definition
| emetics, radiation, and vestibular stimulation |
|
|
Term
|
Definition
initial starch digestion by alpha-amylase and initial triglyceride digestion by lingual lipase
lubrication of ingested food by mucus
protectiong of the mouth and esophagus by dilution and buffering of ingested foods |
|
|
Term
|
Definition
high volume
high K+ and bicarb
low na+ and Cl-
hypotonicity
presence of alpha-amylase, lingual lipase, kallikrein |
|
|
Term
| at lowest flow rate, saliva content |
|
Definition
lowest osmolarity
lowest Na+, Cl-, HOC3-
highest K+ |
|
|
Term
| at highest flow rate, saliva content |
|
Definition
| closest to plasma composition |
|
|
Term
|
Definition
| by parotid, submandibular, and sublingual glands |
|
|
Term
| what eject saliva into the mouth |
|
Definition
|
|
Term
|
Definition
produces initial saliva with composition similar to plasma
initial saliva is isotonic |
|
|
Term
|
Definition
modify the initial saliva by
1. ducts reabsorb Na and Cl --> conc. lower than their plasma conc.
2. ducts secretes K+ and HCO3- --> conc of these ions higher than their plasma conc. |
|
|
Term
|
Definition
| ductal cells to increase the reabsorption of na+ and secretion of K+ |
|
|
Term
| saliva production is control by what? |
|
Definition
parasympathetic and sympathetic NOT hormones
increased by both ^ |
|
|
Term
| how does parasympathtic increase saliva? |
|
Definition
cn. 7 and 9
by increasing transport processes in the acinar and ductal cells and by causing vasodilation |
|
|
Term
| how does sympaththetic increase saliva? |
|
Definition
| by increasing the growth of salivary glands and activating B-receptors. |
|
|
Term
|
Definition
secrete HCL and intrinsic factor
absorb bicarb |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| direct path of vagal stimulation |
|
Definition
| innervates parietal cells and stimulates H+ secretion directly |
|
|
Term
| indirect path of vagal stimulation |
|
Definition
| innervates G cells and stimulates gastrin secretion which then stimulates H+ secretion by an endocrine action |
|
|
Term
|
Definition
| inhibits H+ secretion by blocking the direct pathway which uses ACh as a neurotransmitter |
|
|
Term
|
Definition
| inhibits gastrin secretion --> inhibits H+ secretion |
|
|
Term
|
Definition
| inhibits gastric H+ secretion by direct pathway and indirect pathway |
|
|
Term
| Direct pathway of somatostatin |
|
Definition
| somatostatin binds to receptos on parietal cell and are couple to adenylyl cyclase via a Gi protein, inhibits adenylyl cyclase and decreases cAMP levels. --> somatostatin antagonizes the stimulatory action of histamine on H+ secretion. |
|
|
Term
| Indirect pathway of somatostatin |
|
Definition
| somatostatin inhibits release of histamine and gastrin and thus decreases H+ secretion indirectly |
|
|
Term
| Prostaglandins does what? |
|
Definition
| inhibit gastric H+ secretion by activating a Gi protein, inhibiting adenylyl cyclase and decreasing cAMP level |
|
|
Term
| what is a peptic ulcer disease? |
|
Definition
| an ulcerative lesion of the gastric or duodenal mucosa |
|
|
Term
| where does a peptic ulcer occur? |
|
Definition
| when there is a loss of protective mucous barrier and/or excessive secretion of H+ and pepsin |
|
|
Term
| what are the protective factors? |
|
Definition
| mucus, HCO3, prostaglandins, mucosal blood flow, and growth factor |
|
|
Term
| what are damaging factors? |
|
Definition
| H+, pepsin, H. pylori, NSAIDs, stress, smoking and alcohol |
|
|
Term
|
Definition
gastric mucosa is damaged
gastric H+ secretion is decreased because secreted H+ leaks back through the damaged gastric mucosa.
gastrin levels are increased because decreased H+ secretion stimulates gastrin secretion |
|
|
Term
|
Definition
duodenal mucosa is damaged
gastric H+ secretion is increased
gastrin secretion in response to a meal is increased |
|
|
Term
| how does H. pylori cause duodenal ulcer? |
|
Definition
| inhibits somatostatin secretion (stimulating gastric H+ secretion) and inhibits intestinal bicard secretion. |
|
|
Term
| Zollinger-Ellison syndrome |
|
Definition
| occurs when a gastrin secreting tumor of the pancreas causes increased H+ secretion |
|
|
Term
|
Definition
| blocks H+ secretion by inhibitng cholinergic muscarinic receptors on parietal cells thereby inhibiting ACh stimulation of h+ SECRETION |
|
|
Term
|
Definition
| blocks H2 receptors and inhibits histamine stimulation of h+ secretion |
|
|
Term
|
Definition
| directly inhibits h, k - ATPase and h+ secretion |
|
|
Term
| pancreatic secretion has a lot of what? |
|
Definition
|
|
Term
| pancreatic juice is characterized by? |
|
Definition
high volume
same na and k as plasma
higher hco3 than plasma
lower cl than plasma
isotoncity
pancreatic lipase, amylase, and protease |
|
|
Term
|
Definition
| isotonic, mainly na and cl |
|
|
Term
|
Definition
| isotonic, mainly na and hco3 |
|
|
Term
|
Definition
|
|
Term
|
Definition
| modify initial pancreatic secretion by secreting hco3 and absorbing cl via cl-hco3 exchange |
|
|
Term
| secretin acts on pancreatic..... |
|
Definition
| ductal cells to increase bicarb secretion |
|
|
Term
| what is secretin's second messenger? |
|
Definition
|
|
Term
| CCK acts on pancreatic..... |
|
Definition
| acinar cells to increase enzyme secretion (amylase, lipases, proteases) |
|
|
Term
| what is the second messenger for CCK? |
|
Definition
| IP3 and increased intracellular Ca2+ |
|
|
Term
| ACh acts on pancreatic..... |
|
Definition
| acinar cells to increase enzyme secretion (amylase, lipases, proteases) |
|
|
Term
| what potentiates the effect of secretin on hco3 secretion? |
|
Definition
|
|
Term
| what inititates gallbladder contraction? |
|
Definition
CCK causes contraction of the gallbladder and relaxtion of the sphincter of Oddi
ACh also causes contraction |
|
|
Term
|
Definition
| salt, water, mucus, amylase |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| bile salts, bicarbonate, organic waste products and trace materials |
|
|
Term
|
Definition
| enzymes, salt, water, mucus |
|
|
Term
|
Definition
|
|
Term
| morility pathologies are? |
|
Definition
hyper = diarrhea
hypo = constipation
loss of coordinated m. function = Achalasia, Hirschsprung's
sphincter problem = pyloric stenosis |
|
|
Term
| secretion pathologies are? |
|
Definition
excess acid = ulcers, Zollinger-Ellison, H. pyloris
excess electrolyte and water secretion = Cholera, dehydration
excess cholesterol production
deficient enzymes or bile salts = malabsorption
hepatic storage diseases |
|
|
Term
| digestion and absorption pathologies are? |
|
Definition
malabsorption syndromes = osmotic diarrhea, nutrient deficiency
enzyme deficiency = pancreatic disease, ucosal dysfunction
bile salt deficiency = liver disease
deficient or inappropriate nutrient intake |
|
|
Term
| paracrine is a substance that is? |
|
Definition
| secreted from one cell and influences, a second adjacent cell |
|
|
Term
|
Definition
| specific type of paracrine, namely a substance secreted from a nerve terminal that influences another nerve or a neighboring tissue |
|
|
Term
| autocrine is a substance that? |
|
Definition
| influences the cell from which it is secreted |
|
|
Term
| What stimulated the secretion of bicarb from the pancreas? |
|
Definition
|
|
Term
| where are secretin-secreting cells located at? |
|
Definition
|
|
Term
| what stimulates secretin cells to secrete? |
|
Definition
|
|
Term
| what causes a decrease in secretion of secretin? |
|
Definition
| increase in pH due to bicarb entering duodenum |
|
|
Term
| name some hydrophoic hormones? |
|
Definition
|
|
Term
| name some hydrophilic substance? |
|
Definition
| polypeptide, glycoproteins, some amines (epinephrine) |
|
|
Term
| hormones with receptors in the nucleus exerts its effect through.... |
|
Definition
| DNA-dependent RNA synthesis |
|
|
Term
| Phosphatidyl inositol is converted to what? |
|
Definition
| IP3 which releases Ca2+ from ER and DAG which activates protein kinase C |
|
|
Term
| Ghrelin is secreted from? |
|
Definition
|
|
Term
|
Definition
| gastric antrum and duodenal mucosa |
|
|
Term
|
Definition
| durodenal and jejeunal mucosa |
|
|
Term
| secreting is secreted from |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
smooth m. relaxation (LES)
vasodilation
stimulate water movement into pancreatic secretions and into small intestine
increases cAMP to activate CFTR chloride channel on the apical surface of cells in small intestine. |
|
|
Term
| what is required for CCK activity? |
|
Definition
| sulfation of tyrosine at postiion 7 |
|
|
Term
| what does CCK resemble is it is not activated by sulfation? |
|
Definition
|
|
Term
| when is little gastrin called gastrin II? |
|
Definition
| when the tyrosine at postiion 6 from the C-terminal end is sulfated |
|
|
Term
|
Definition
| stimulate mass contractions of stomach and small intestine during the post-absorptive state |
|
|
Term
|
Definition
| stimulate gastric secretion of HCL from parietal cells and stimulates increased parietal cell mass int he gastric mucosa |
|
|
Term
|
Definition
stimulates pancreatic enzyme secretion
gall bladder contraction & relaxation of sphincter of oddi
increased exocrine cell mass in the pancreas
inhibits gastric emptying and appetite |
|
|
Term
|
Definition
stimulate pancreatic and biliary bicarbonate secretion
increased exocrine cell mass in the pancreatic tissue
inhibit acid secretion by parietal cells
inhibit gastrin secretion by g-cells
inhibit gastric emptying |
|
|
Term
|
Definition
stimulate insulin secretion during absorption of glucose
inhibits acid secretion by pareital cells, gastrin secretion by g-cells, and gastric emptying |
|
|
Term
|
Definition
stimulates food intake, GH secretion, gastric secretion and emptying
inhibits insulin secretion |
|
|
Term
|
Definition
|
|
Term
|
Definition
| vagal input, peptides, amino acids, and distension |
|
|
Term
|
Definition
| peptides, amino acids, FFA in durodenum |
|
|
Term
|
Definition
|
|
Term
|
Definition
| glucose, amino acids, and fat in duodenum |
|
|
Term
| histamine is from what cells and where? |
|
Definition
|
|
Term
| what is histamine's action? |
|
Definition
stimulates HCL secretion from parietal cells
stimulates gastrin secretion from G-cells
potentiates effects of gastrin and ACh |
|
|
Term
| what secretes somatostatin and from where? |
|
Definition
| from d-cells in the stomach |
|
|
Term
| what is somatostatin's action? |
|
Definition
inhibits parietal cells, inhibit G-cells
inhibit growth hormone (when released into anterior pituitary)
inhibit insulin and glucagon (when released into pancreas) |
|
|
Term
| what are ACh and norepinephrine? |
|
Definition
| major postganglionic transmitters of PNS and SNS |
|
|
Term
|
Definition
| post-ganglionic vagal transmitter to g-cell |
|
|
Term
|
Definition
vasodilate splanchnic vessels
relaxes intestinal smooth muscle (NO) |
|
|
Term
| what does enkephalins do? |
|
Definition
| increase smooth muscle tone, mediate sphincter contractions, and slow transit time |
|
|
Term
|
Definition
GI to brain
functional status to NTS
pain to thalamus |
|
|
Term
|
Definition
|
|
Term
| two types of extrinsic efferents is |
|
Definition
|
|
Term
|
Definition
somotic motor from nucleus ambiguus
visveral motor from dorsal motor nucleus of X
ganglia within neural plexi |
|
|
Term
|
Definition
| major effects on vascular tone, ganglia outside plexi |
|
|
Term
| what makes up interconnected plexi: |
|
Definition
myenteric: between longitudinal and circular muscle layers
submucosal: between circular and muscularis mucosa |
|
|
Term
|
Definition
PNS mainly
not dependent on external input |
|
|
Term
| intrinsic plexi contains: |
|
Definition
PNS ganglia
cells sensing: stretch and luminal pH, fat, amino acids
cells mediating: contractile strength, blood flow, secretion from endocrine and other cells |
|
|
Term
| intrinsic plexi distributes to |
|
Definition
central to CNA
btwn plexi
locally to cells in tract several mm up and down the tract |
|
|
Term
|
Definition
ACh stimulatory
VIP and NO inhibitory |
|
|
Term
|
Definition
Ca2+ enters cell through voltage-gated channels
binds to calmodulin
ca-calmodulin complex activates myosin light chain kinase
kinase phosphorylates the myosin head
actin-myosin interaction leads to contraction
dephosphorylation leads to relaxation |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| interstitial cells of Cajal in the enteric plexi |
|
|
Term
| what causes propagation of slow waves? |
|
Definition
| interstitial cells of Cajal |
|
|
Term
|
Definition
|
|
Term
|
Definition
| sphincters having a contractile tone |
|
|
Term
| where is the striated muscle at? |
|
Definition
| tongue, pharyngeal constrictors. laryngeal, UES, and upper third of esophagus |
|
|
Term
| where is the smooth muscle at? |
|
Definition
| lower two thirds of esophagus and LES |
|
|
Term
| what are the neural controls for skeletal and smooth m.? |
|
Definition
skeletal = somatic branch of vagus (NA)
smooth = visceral branch of vagus (DMNX) |
|
|
Term
| enteric nervous system recieves input from where? |
|
Definition
|
|
Term
| Primary peristalsis depends on what? |
|
Definition
| vagal output (extrinsic nervous system) |
|
|
Term
| secondary peristalsis invovles what? |
|
Definition
|
|
Term
| secondary peristalsis is initiated by what? |
|
Definition
|
|
Term
| secondary peristalsis is mediated by |
|
Definition
|
|
Term
| process for primary swallows |
|
Definition
1. respiration inhibited and nasopharynx closed
2. tongue and pharyngeal m. move food toward esophagus
3. glottis closed
4. UES opens
5. contractile wave moves down esophagus
6. orad portion of stomach relaxes
7. LES opens |
|
|
Term
| what causes LES to contract? |
|
Definition
| ACh (excitatory branch of vagus) |
|
|
Term
| how do you increase tone of LES? |
|
Definition
|
|
Term
|
Definition
| VIP & NO from inhibitory branch of vagus |
|
|
Term
| Acid reflux (GERD) depends on |
|
Definition
| posture and position relative to diaphragm |
|
|
Term
| how do you increase acid reflux? |
|
Definition
with recumbant position and with movement of LES into thorax
inadequate closure of the LES |
|
|
Term
|
Definition
atmospheric
it increases with swallow |
|
|
Term
| UES (above thorax) pressure = tonically contracted |
|
Definition
pressure > atm
decreases to atm when relaxed |
|
|
Term
| esophageal (within thorax) pressure = |
|
Definition
pressure < atm at rest
increases under contractile wave |
|
|
Term
| LES (in abdomen) pressure = |
|
Definition
resting: P > atm
tonically contracted: P > atm |
|
|
Term
|
Definition
| pressure decreases before swallow arrives (receptive relaxation) |
|
|
Term
|
Definition
|
|
Term
| what happens in achalasia? |
|
Definition
absence of transmitters mediating relaxation
absence of neurons, iccs in lower plexi
bloackage of passage of both solids and water
results in mega-esophagus |
|
|
Term
| what mediates gastric motility? |
|
Definition
|
|
Term
| what increases the force of contraction of gastrin? |
|
Definition
|
|
Term
| what decreases force of contraction leading to delayed emptying? |
|
Definition
|
|
Term
|
Definition
| decreased contractile function in Diabetes resulting from impaired autonomic function (vagus) |
|
|
Term
| How do you neutralize gastric contents? |
|
Definition
increase secretion of secretin --> stimulates bicarb secretion
increase CCK secretion --> stimulates gall bladder contraction --> increases bile salts and bicarb |
|
|
Term
| what does increases in CCK secretion do? |
|
Definition
stimulates gall bladder contraction --> increases bile salts and bicarb
dilates sphincter of oddi
stimulate secretion of pancreatic enzymes
potentiates bicarb secretion by pancreas |
|
|
Term
| how do you delay gastric emptying? |
|
Definition
decrease the force of contraction of pylorus
decrease vagal output to stomach to decrease force of stomach contractions
increase force of duodenal contraction
increase secretin secretion
increase CCK secretion |
|
|
Term
|
Definition
|
|
Term
|
Definition
incompetent pyloric sphincter
rapid emptying
osmotic load in duodenum draws in water from the circulatory system leading to decrease MAP
decrease MAP leads to SNS activation
large shift of water out of circulatory system can leave to CN collapse (syncopy) |
|
|
Term
| central control of vomiting consist of? |
|
Definition
| chemoreceptor trigger zone and emetic center |
|
|
Term
| chemoreceptor trigger zone is located in |
|
Definition
| area postrema (blood-brain barrier is permeable) |
|
|
Term
| emetic center is located in the? |
|
Definition
| dorsalateral reticular formation |
|
|
Term
| what does emetic center do? |
|
Definition
coordinates motor responses
recieves input from: CTZ, vestibular system, thalamus, hypothalamus, cortex, limbic system |
|
|
Term
|
Definition
|
|
Term
| vomiting center does what? |
|
Definition
coordinates afferent input from central and peripheral sites
initiates vomiting response |
|
|
Term
| metabolic consequences of vomiting |
|
Definition
metabolic alkalosis
volume loss leads to increase Na reabsorption and increase H excretion |
|
|
Term
|
Definition
1. prodroma precedes retching
2. retching preces vomiting
3. positive pressure in both abdomen and thorax
4. UES relaxes, increase force of intestingal contraction |
|
|
Term
| small intestinal motility starts where and its rate is |
|
Definition
duodenum
independent of gastric BER
12/min |
|
|
Term
| small intestinal motility produces |
|
Definition
|
|
Term
| BER does what as one moves distally? |
|
Definition
|
|
Term
|
Definition
| increase contractile force and are used to treat diarrhea because increased contractile force in sphincters increases transit time |
|
|
Term
| contraction of large intestine leads to |
|
Definition
| formation of haustrations |
|
|
Term
|
Definition
congenital lack of ganglion cells and interstitial cells of Cajal in plexi in colon
affects internal anal sphincter inhibiting relaxation
results in megacolon and constipation |
|
|
Term
|
Definition
| section of bowel slides into the next |
|
|
Term
| sphincter pressure decreases with what? |
|
Definition
ileal distension
AND
gastroiliac reflex that occurs with eating |
|
|
Term
| sphincter pressure increases with what? |
|
Definition
|
|
Term
| rectosphincteric reflex = |
|
Definition
| increase pressure in rectum |
|
|
Term
| what happens with rectospincteric reflex? |
|
Definition
afferent signal of distension
internal sphincter relaxes
centrally mediated relaxation or contraction of external sphincter
reflex contraction of distal colon and rectum
voluntary increase in abdominal pressure and relaxation of pelvic floor |
|
|
Term
|
Definition
| osmotic water movement with non-absorbed particles (malabsorption) |
|
|
Term
|
Definition
| over-secretion of water (activation of CFTR chloride channels) |
|
|
Term
|
Definition
| damage to mucosa depends on whether inflammartory or non-inflammatory |
|
|
Term
| altered motility diarrhea = |
|
Definition
| rapid transit time decreases water and nutrient absorption leading to increase volume of stool |
|
|
Term
| salivary secretion comes from |
|
Definition
parotid gland
submandibular gland
sublingual gland |
|
|
Term
| two major proteins in saliva |
|
Definition
|
|
Term
|
Definition
aka ptyalin
produced in parotid glands
digestion of starch
in acinar cells |
|
|
Term
|
Definition
produced in sublingual and submandibular gland
responsible for saliva's viscosity |
|
|
Term
|
Definition
| combats bacteria by lysin bacterial cell wall by having lactoferrin bind iron strongly and depriving microorganisms of sources of iron vital to their growth |
|
|
Term
|
Definition
active in GI tract with an acidic pH optimun and not affected by surface active detergents like bile salts, MCFA, and lecithin
breaks down dietary lipids |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| kallikrein - peptidase that converts kininogent o bradykinin |
|
|
Term
| acinar cells in submandibular does what? |
|
Definition
| produce primary secretion |
|
|
Term
| duct cells in submandibular does what? |
|
Definition
|
|
Term
|
Definition
| increasing intracelluar Ca2+ or increasing cAMP |
|
|
Term
| parasympathetic control of salivary secretion = |
|
Definition
| stimulates enzyme secretion, metabolic rate, myoepithlial cell contraction, blood flow and is necressary to prevent atrophy |
|
|
Term
| sympathetic control of salivary secretion = |
|
Definition
| VIP and Substance P stimulate the same variables (not growth), effect on blood flow biphasic |
|
|
Term
| how does aldoesterone alter saliva? |
|
Definition
| decreases Na which alters the salt sensitivity of taste receptors |
|
|
Term
|
Definition
| a congenital absence of salivation produces dry mouth |
|
|
Term
|
Definition
| chronic autoimmune disease, fibrosis and atrophy of glands leading to decreased salivation |
|
|
Term
| what is a secondary affect to the use of anti-cholinergics? |
|
Definition
|
|
Term
|
Definition
| basic unit, consisting of the acinus, intercalated duct, striated duct, and excretory duct |
|
|
Term
|
Definition
has a lot of ER and zymogen granules
salivary amylase made and stored in zymogen granules and secreted from serous acinar cells |
|
|
Term
| excretory duct cells secrete |
|
Definition
| epidermal growth factor, ribonuclease, amylase, and proteases |
|
|
Term
| what is the two-stage model of salivary secretion? |
|
Definition
1. acinar primary secretion is isotonic, plasma-like
2. ductal cells modify secretions to create hypotonic secrretion that is high in K+ & HCO3 and low in Na and Cl |
|
|
Term
| apical Ca activated Cl channel does what? |
|
Definition
| Cl is secreted which creates an electrochemical driving force for Na and an osmotic gradient for the movement of H20 |
|
|
Term
| what happens in duct cells? |
|
Definition
reabsorption of NaCl and poorly permeable to H2O
basolateral Cl channel active for absorption of Cl without H2O = hypotonic secretion |
|
|
Term
| at high flow rate saliva becomes |
|
Definition
nearly isotonic
bicarb secretion is high relative to plasma |
|
|
Term
| saliva is __________ to plasma, why? |
|
Definition
hypotonic
because ductal cells are not permeable to water just salt |
|
|
Term
parasympathetic causes _________ saliva
sympathetic causes _____________ saliva |
|
Definition
|
|
Term
| three main glands of glandular gastric mucosa = |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| parietal cells, peptic chief cells, mucous neck cells, enteroendocrine cells (G and D) |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| convert pepsinogen to pepsin --> protein digestion |
|
|
Term
|
Definition
|
|
Term
|
Definition
| pepsinogen and gastric lipase |
|
|
Term
|
Definition
| histamine which stimulate acid secretion |
|
|
Term
|
Definition
gastrin which stimulate acid secretion (HCl and pepsinogen)
activates gastroileal relfex which moves chyme |
|
|
Term
|
Definition
| somatostatin which inhibits acid secretion |
|
|
Term
| how does gastric parietal cells secrete HCl? |
|
Definition
H-K ATPase primary active process, pumps H into parietal cell secretory canaliculi
carbonic anhydrase rxn produces H + HCO3
HCO3 transported into the blood leaving the stomach via HCO3/CL exchanger
Cl leaks out of the cell via cl channels |
|
|
Term
|
Definition
1. pareital cells rich in H+ and Cl
2. non-parietal cells or basal secretion rich in Na |
|
|
Term
| what does prolonged vomiting cause? |
|
Definition
| hypochloremic, metabolic alkalosis due to loss of HCl |
|
|
Term
|
Definition
| path by which bile is secreted by the liver then transported to the first part of the duodenum |
|
|
Term
| acinar cells in the pancreas secrete |
|
Definition
|
|
Term
| centroacinar cells in the pancreas secrete |
|
Definition
| primary aqueous secretion |
|
|
Term
| ductal cells of the pancreas |
|
Definition
|
|
Term
| at low flow rates, primary secretion is |
|
Definition
| a plasma-like solution of electrolytes and H2O |
|
|
Term
| what are the three active (Stimulated) phases: |
|
Definition
| Cephalic, gastric, and intestinal |
|
|
Term
|
Definition
| idea, sight, odor, taste, hypoglycemia |
|
|
Term
|
Definition
| food in stomach, distension |
|
|
Term
|
Definition
|
|
Term
| at rest, no food in the stomach what happens? |
|
Definition
| food buffers the acid, H+ is high, pH low, Hcl secretion in inhibited |
|
|
Term
|
Definition
| H+ is buffered by the food, the pH rises, the inhibition of secretion is removed --> increase HCl secretion |
|
|
Term
| stimulators of gastric secretion is |
|
Definition
| vagus, gastrin, histamine, ghrelin |
|
|
Term
|
Definition
direct stimulation of parietal cell
stimulates ECL cell to secrete histamine
inhibits d-cell secretion of somatostatin (inhibitor) |
|
|
Term
|
Definition
| stimulates G-cell to secrete gastrin |
|
|
Term
|
Definition
direct stimulation of parietal cell
stimulates ECL cell to secret histamine |
|
|
Term
|
Definition
| directly stimulates parietal cell |
|
|
Term
|
Definition
| directly stimulates parietal cell |
|
|
Term
|
Definition
| somatostatin, secretin, CCK &GIP, prostaglandins |
|
|
Term
|
Definition
inhibits parietal cell & gastrin secretion
stimulates inhibitory g-protein which decreases cAMP |
|
|
Term
| secretin is secreted with |
|
Definition
|
|
Term
|
Definition
| inhibits parietal cell, inhibits gastrin secretion, stimulates somatostatin secretion |
|
|
Term
| CCK & GIP is secreted with |
|
Definition
|
|
Term
|
Definition
| inhibit parietal cell and inhibit gastrin secretion |
|
|
Term
| prostaglandins does what? |
|
Definition
| inhibit parietal cell and stimulates inhibitory g-protein which decreases cAMP |
|
|
Term
| what controls somatostatin secretion? |
|
Definition
GRP --> stimulates G-cell
ACh --> inhibits D-cell |
|
|
Term
| what stimulates parietal cells? |
|
Definition
|
|
Term
| what inhibits parietal cells? |
|
Definition
| somatostatin, prostaglandins, secretin, CCK |
|
|
Term
|
Definition
| activation of phospholipase C in Gi tract = yield IP3 and DAG --> increased entry of Ca2+, stimulates secretions and smooth m. contraction |
|
|
Term
|
Definition
in the heart
ACh activates inhibitory g-protein to decrease cAMP producing a decreased heart rate and conduction velocity |
|
|
Term
|
Definition
| activation of phospholipase C in GI tract = increased entry of Ca2+ and simulates secretion |
|
|
Term
| how do diagnose gastrinoma? |
|
Definition
infuse Ca or secretin
Ca infusion that leads to a large increase in gastrin results in greater HCl secretion = gastrinoma
infuse secretin normally inhibits HCl secretion but increases in patients with gastrinoma. |
|
|
Term
| inflammation in the antral region causes what? |
|
Definition
| increases acid secretion which stimulates G cell and inhibits D cell, increases gastrin (which stimulates parietal cell and ECL cell) |
|
|
Term
| inflammation in the body of the stomach does what? |
|
Definition
| directly inhibits parietal and ECF cells resulting in a decrease in acid secretion |
|
|
Term
|
Definition
generate NH3 and CO2 by urease which neutralizes the acid and allows for colonization and further growth
NH3 damages the mucosal wall |
|
|
Term
| what are the enzymes from acinar cells in the pancrease? |
|
Definition
amylase
lipase (with co-lipase)
endopeptidases (trypin with trypsin inhibitor, chymotrypsin, and elastase)
exopeptidases (carboxypeptdases A & B) |
|
|
Term
| ACh does what in the pancreas? |
|
Definition
stimulates both aqueous and enzyme fractions by
1. mediating cephalic phase secretion
2. vagal-vagal reflex to gastric stretch and duodenal receptors |
|
|
Term
| what does the cephalic/gastric phase do in pancreas? |
|
Definition
| increase vagal output in order to stimulate M3 muscarininc receptors on the acinar cells to increase secretion |
|
|
Term
| during intestinal phase in pancreas, what stimulates what? |
|
Definition
stimulation is mostly hormonal
secretin stimulates bicarb secretion from ducts
CCK stimulates enzyme secretion from acinar cells |
|
|
Term
| how do you test for lactose intolerance? |
|
Definition
H2 test.
because the lactose cannot be hydrolyzed to glucose, it is metabolized by bacterial which releases H2. |
|
|
Term
| Name the carriers and what they carry across a cell for carbohydrates. |
|
Definition
Apical side:
SGLT1 = glucose or galactose with 2Na
GLUT5 = fructose
basolateral side:
GLUT2 = glucose, galactose, and fructose |
|
|
Term
|
Definition
| tripeptide/dipeptide uptake more rapid than AA uptake due to higher effectiveness of oligopeptide transporter (pept1) |
|
|
Term
|
Definition
metabolic disorder affecting absorption of nonpolar AA
L-phenylalanine cannot pass through a cell |
|
|
Term
| pacnreatic lipase does what? |
|
Definition
| hydrolyzes TAGs to FAs and 2-MG |
|
|
Term
| Colipase-dependent pancreatic lipase activity |
|
Definition
procolipase is an inactive form secreted by pancreas and activated in intestinal lumen by trypsin
required to aid binding of pancreatic lipase to the micellar lipid-water interface |
|
|
Term
| what does elevated serum lipase indicate? |
|
Definition
|
|
Term
| cells at tips of intestinal villi are specialized for? |
|
Definition
| absorption of ion and H2O |
|
|
Term
| crypt cells are specialized for |
|
Definition
| secretion of ions and H2O |
|
|
Term
| where does the bulk of Na absorption occur? |
|
Definition
|
|
Term
|
Definition
| extracellular hypotonicity or strong hyperpolarization |
|
|
Term
| Where is K+ excretion regulated? |
|
Definition
|
|
Term
| what is increased in cholera? |
|
Definition
| cAMP conc. in intestinal epithelial cells |
|
|
Term
| iron must be in which state to be absorbed? |
|
Definition
|
|
Term
| what acts as solubilizing agents for ferric iron? |
|
Definition
| gastric acidity and vitamin C |
|
|
Term
| what blocks ferrous absorption? |
|
Definition
|
|
Term
| where is ferrous mainly absorbed? |
|
Definition
|
|
Term
cofactor =
cofactor that is organic = |
|
Definition
nonprotein component of an enzyme
coenzyme |
|
|
Term
| what are fat-soluble vitamins? |
|
Definition
A,D,E, and K
associated with lipids in foods and body
dont dissolve in water or urine
stored in body in fat compartments and may become toxic
do not form classical coenzyme structures |
|
|
Term
| what are water-soluble vitamins? |
|
Definition
| thiamin, riboflavin (B2) niacin, b6, b12, biotin, pantothenic acid, folate |
|
|
Term
| what is the function of vitamin E? |
|
Definition
| protects membrane unsaturated FAs |
|
|
Term
| what happens if you have a vitamin A deficiency? |
|
Definition
|
|
Term
| The function of vitamin D? |
|
Definition
| Ca2+ regulation, bone mineral density |
|
|
Term
| what happens if you have a vitamin D deficiency (sequence of events)? |
|
Definition
| lack of vitamin D = inability to make 1,25-diOH-D --> decreased absorption of dietary calcium and increased loss of calicum in feces --> bones are affected |
|
|
Term
| what is the function of vitamin K? |
|
Definition
essential cofactor carboxylation of glutamic acid residues
carboxylated glutamate residues assist Ca2+ binding required for the formation of blood-clotting protein complexes |
|
|
Term
|
Definition
it is an anticoagulant
blocks vitamin K cycle from reusing vitamin K |
|
|
Term
| what is the function of thiamin? |
|
Definition
invovled in the metabolism of enery molecules such as glucose
found on membranes of neurons |
|
|
Term
|
Definition
| part of two coenzymes (NAD, NADP) |
|
|
Term
|
Definition
| inability to absorb dietary typtophan, which results in niacin deficiency |
|
|
Term
|
Definition
| HMG-CoA reductase in the conversion of acetate to cholesterol |
|
|
Term
|
Definition
nearest to entry of hepatic artery
most resistant to injury
oxidative energy metabolism here |
|
|
Term
| Bile acid-dependent secretion |
|
Definition
water follows secretion of bile acids
secretion is proportional to bile acids returned in portal blood and new bile acids synthesized.
synthesis increases when amount return decreases |
|
|
Term
| Bile acid-independent secretion |
|
Definition
| cholangiocytes stimulated by secretin to secrete water and HCO3 |
|
|
Term
| what happens when you infuse HCL into the duodenum? |
|
Definition
| duodenum contraction increases and stomach contraction decreases |
|
|
