Term
| what are the functions of the GI tract, which are the main functions. explain a little about each |
|
Definition
motility: propell, reduce size, mix, proper rate
secretion: electrolytes, galnds
**digestion: to make molecules absorbable
**absorption: nutrients, electrolytes, water |
|
|
Term
what type of tissue is the mouth
what is the muscle of the lips
what is the vermillion border |
|
Definition
stratified squamous
border between skin of mucosa and face
obricularis oris |
|
|
Term
| what is the tounge covered with, anchored by, and its function |
|
Definition
covered with mucosa and papillae, anchored to hyoid
chewing, swallowing, speech |
|
|
Term
| where are taste buds, what can they taste |
|
Definition
they are nerve cells on pepillae
taste sweet, sour, bitter, salty, and umami |
|
|
Term
|
Definition
|
|
Term
what is the difference between intrinsic and extrinsic salivary glands
what are the extrinsic ones |
|
Definition
intrinsic are in oral mucosa and secrete all the time
extrinsic only secrete around eating. parotid, submandibular, sublingual |
|
|
Term
| what is saliva composed of |
|
Definition
| water, ions, mucous, enzymes |
|
|
Term
| what are the functions of saliva |
|
Definition
| moisten, dissolve food, start digestion, antibacterial, antiviral |
|
|
Term
| how does the pharynx contribute to digestion, what type of tissue is it |
|
Definition
stratified squamous
three constrictor muscles
oropharynx and laryngopharynx are used |
|
|
Term
| how does the esophagus contribute to digestion |
|
Definition
| skeletal muscle controlled by vagus pushes food down, collapses when empty |
|
|
Term
| what are the functions of the stomach |
|
Definition
| temporary storage, mixing, break down protein with pepsin, HCl antimicrobial, absorb water electrolytes asprin alcohol |
|
|
Term
| what are some characteristics of the epithelium / lining of the stomach |
|
Definition
simple columnar
glands open into pits
secrete bicarbonate
rugae: longitudinal folds distentable
muscularis: circular and longitudinal |
|
|
Term
| what are the cell types of the stomach, give a general function |
|
Definition
parietal: secrete HCl and intrinsic factor
Chief: secrete pepsinogen
mucous neck cells |
|
|
Term
| where does the small intestine get blood from, where does it drain |
|
Definition
superior mesenteric arteries
hepatic portal vein |
|
|
Term
| by what structure does the duodenum recieve enzymes from the pancreas |
|
Definition
|
|
Term
| what is the biggest part of the small intestines |
|
Definition
|
|
Term
| what structures help with absorption in intestines |
|
Definition
| circular folds (plicae circularis), villi on simple columnar cells, microvilli, and lacteals (fat absorption) |
|
|
Term
| what are some structural characteristics of the large intestines. beriefly describe them / purpose (cell tyoes, structural markers, tissue characteristics) |
|
Definition
teniae coli: 3 longitudinal muscle strips
haustra: sacs
epiploic ependages: omental folds or eritoneum or fat pouches
cecum: holds symbiotic microbes
ileocecal valve
columnar cells: absorb water and electrolytes
goblet cells: secrete mucous to lubricate
lymphoid tissue: control bacteria
NO villi! |
|
|
Term
| what are the layers of the GI tract and their sublayers from lumen out (10 layers, 6 sub) |
|
Definition
1. lumen
2. mucosal layer :epithelial cells, lamina propria, muscularis mucosae
3. submucosa
4. submucosal / meissner's plexus
5. muscularis externa: circular muscle, myenteric plexus, longutidunal muscle
6. serosa
7. peritoneal cavity |
|
|
Term
| what are the parts of the mucosal layer of the GI tract, what are their functions |
|
Definition
epithelial cells: absorb nutrients, secrete mucous (goblet cells), form barrier
lamina propria: CT, blood, lymph. first line of immune defense (MALT)
muscularis mucosae: contracts locally |
|
|
Term
| what is the submucosa of the GI tract made of, what is its function |
|
Definition
collagen, elastin, glands, vessels
helps regain shape after processing |
|
|
Term
| what is the function of the muscularis externa and the different parts |
|
Definition
peristalsis and segmentation
circular: squeezes
longitudinal: shortens |
|
|
Term
| describe the muscle cells of the GI tract (shape, configuration, function) |
|
Definition
spindle shaped, one nuclri, no striations, in sheets, no sarcomere
slow contraction, fatuge resistant
does not always need nervous signal
stimulated by stretch too |
|
|
Term
| what is another name for the serosa, what type of tissue is it |
|
Definition
| simple squamous epithelium with areolar CT beneath it |
|
|
Term
| what organs are retroperitoneal |
|
Definition
| kidney, ureter, suprarenal gland, great vessels, paired branches |
|
|
Term
| what does the peritoneal cavity contain |
|
Definition
| intestines, stomach, liver |
|
|
Term
| what are the steps in the digestive process, briefly explain each (6) |
|
Definition
1. ingestion
2. propulsion: swallowing, peristalsis
3. mechanical digestion: chew, chrun, mix
4. chemical digestion: enzymes
5. absorption: transport into blood or lymph
6. defecation: elimination via feces |
|
|
Term
| explain the process of defecation |
|
Definition
| wall stretching triggers parasympathetic reflex, contraction of smooth muscle, relaxation of internal anal sphinctor, voluntary relaxation of external anal sphincter (aided by diahragm and abdnominal wall muscles) |
|
|
Term
| what is the extrinsic innervation of the GI tract, general purpose of each part |
|
Definition
autonomic nervous system
parasympathetic: stimulate digestion
sympathetic: stop digestion |
|
|
Term
| what does the parasympathetic part of the vagus nerve innervate in GI tract, what type of innervatin |
|
Definition
upper GI, striated muscle of esophagus
many afferent (mechanoreceptors, chemoreceptors, vasovagal reflexes)
some efferent |
|
|
Term
| what does the phrenic nerve innervate in GI tract |
|
Definition
| lower GI tract (striated muscle of external anal canal too) |
|
|
Term
| where do sympathetic preganglionic cell bodies of extrinsic nervous system synapse |
|
Definition
| celiac, superior mesenteric, inferior mesenteric, and hypogastric ganglia |
|
|
Term
| what neurotransmitters to postganglionic fibers of the extrinsic sympathetic nervous system are there |
|
Definition
| adrenergic release NE and N |
|
|
Term
| where do postganglionic fibers of the extrinsic sympathetic nervous system synapse |
|
Definition
some go to submucosal or myenteric plexuses
some go to smooth myscle, endocrine, or secretory cells |
|
|
Term
| where do the postganglionic parasympathetic fibers of the extrinsic nervous system go, why |
|
Definition
| myenteric and submucosal plexuses to coordinate information |
|
|
Term
| what types of parasympathetic neurons are there for the GI tract, what neurotransmitters do they use |
|
Definition
cholinergic: ACh
peptidergic: substance P, neuropeptide, vasoactive inhibitor peptide (VIP) |
|
|
Term
| where are the cell bodies of the enteric nervous system, what do they control |
|
Definition
submucosal and myenteric plexuses
contractile, secretory, and endocrine functions |
|
|
Term
| what is different about the neurotransmitters of the enteric nervous system |
|
Definition
the release neurocrines/neurochemicals and neuromodulators
nerves may secrete more than one |
|
|
Term
| what and how does the enteric nervous system communicate with |
|
Definition
comminicates with autonomic nervous system
recieves info via chemo and mechanoreceptors and sends info back to GI tract
info is relayed between ganglia by interneurons |
|
|
Term
| what qualifies something to be a hormone |
|
Definition
must be secreted in response to physiologic stimulus, carried in blood to distant site of action, independent function from neural activity
must have been isolated, purified, identified, and synthesized |
|
|
Term
| physically describe the endocrine cells of the mucosa |
|
Definition
single or in small groups dispersed over GI tract
NO glands |
|
|
Term
| what are the types of hormones and almost hormones in the GI tract |
|
Definition
gastrin, CCK, secretin, GIP
almost hormones: motilin, pancreatic polypeptide, enteroglucagon |
|
|
Term
| what are the types of gastrin, explain when each is used. where are they secreted from |
|
Definition
little (G17): in response to meal
big (G34): between meals, more common
C-terminal tetrapeptide: fragment that causes lesser effects
secreted from G (gastrin) cells in the antrum of the stomach |
|
|
Term
| what can signal gastrin release what can turn them off |
|
Definition
peptides, AA (phenyalalnine, tryptophan), distension of stomach, vagal reflexes (GRP/bombesin)
low pH or somatostatin turns them off |
|
|
Term
| what are the actions of gastrin |
|
Definition
cause parietal cells to release H
increase trophic growth of mucosa |
|
|
Term
| what are the types of CCK and its receptors, explain why each are used. where is CCK secreted from |
|
Definition
CCK A receptor: CCK only
CCK B receptor: CCK and gastrin
C-terminal hepatapeptide (CCK-7): smallest part of CCK needed for function
I cells of duodenum and jejum mucosa |
|
|
Term
| what stimulates CCK release |
|
Definition
| peptides, AA, FA (not TG) |
|
|
Term
|
Definition
contraction of gallbladder and relaxation of sphinctor of Oddi to release bile
secreation of pancreatic enzymes and bicarbonate
growth of pancreas and gallbladder
inhibit gastric emptying to help absorb fat |
|
|
Term
| what stimulates secretin release, from where |
|
Definition
pH < 4.5 (H+), Fa
S cells in duodenum |
|
|
Term
|
Definition
secretion of pancreatic and biliary bicarbonate
inhibit gastrin |
|
|
Term
| what stimulates GIP release from where |
|
Definition
FA, AA, oral glucose (only one with all three)
K cells in duodenum and jejunum |
|
|
Term
|
Definition
stmulates B cells in pancreas to release insulin
decrease H secretion |
|
|
Term
| where is moltilin do, where is it secreted from and why |
|
Definition
upper duodenum during fasting
increase motility, initiates inter-digestive myoelecric complexes (90 min intervals) |
|
|
Term
| where is pancreatic polypeptide secreted from and why, what does it do |
|
Definition
pancrease in response to carbs, proteins, and lipids
inhibits pancreas secretion of bicarbonate and enzymes |
|
|
Term
| where is enteroglucagon secreted from and why, what does it do |
|
Definition
intestinal cells in response to decreased blood glucose
tells liver to increase glycogenolysis and gluconeogenesis |
|
|
Term
| what are paracrines, what are the ones in the GI tract, how do they work |
|
Definition
secreted by endocrine cells and act locally unlike hormones
somatostatin and histamine |
|
|
Term
| what is somatostatin secreted by and why, what does it to |
|
Definition
secreted by D cells (endocrine and paracrine) in mucosa in response to low pH
secreted by hypothalamus by delta cells of endocrine pancreas
inhibits H secretion |
|
|
Term
| what makes histamine a paracrine peptide, what does it do for the GI tract |
|
Definition
it is not a peptide.
stimulates H secretion by parietal cells |
|
|
Term
| what are neurocrines, what ones are in the GI tract |
|
Definition
peptides made in neurons
ACh, NE, VIP, GRP, enkephalins, neuropeptide Y, substance P |
|
|
Term
| what does ACh do in the GI tract |
|
Definition
increase contraction in wall, salivation, gastric and pancreas secretion
decrease contraction in sphinctors |
|
|
Term
| what does NE do in the GI tract |
|
Definition
increase sphinctor contraction and salivation
decrease contraction of wall |
|
|
Term
| what does vasoactive intestine peptide do in the GI tract |
|
Definition
increase intestinal and pancreatic secretion
decrease contraction of wall |
|
|
Term
| what does gastrin releasing peptide or bombesin do in the GI tract |
|
Definition
|
|
Term
| what do enkephalins or opiates do in the GI tract |
|
Definition
increase wall contraction
decrease secretion |
|
|
Term
| what does neuropeptide Y do in the Gi tract |
|
Definition
| decrease contraction of wall and secretions |
|
|
Term
| what does substance P do inthe GI tract, how is it released |
|
Definition
co-secreted with ACh
increases contraction of wall and secretions |
|
|
Term
| what is the cause of zollnger-ellison syndrome |
|
Definition
gastrinoma: gasrin secreting tumor
in B cells of pancreas |
|
|
Term
| what are the signs of zollnger-ellison syndrome |
|
Definition
| high H secretion, hypertrophy of gastric mucosa, duodenal ulcers, acidification of lumen deactivates pancreatic lipase, decreased fat digestion, steatorrhea |
|
|
Term
| what is the treatment for zollnger-ellison syndrome |
|
Definition
H2 receptor blockers (cimetidine)
H+ pump inhibitors (omeparazole)
tumor removal
gastric resection |
|
|
Term
| what complication can occur in a gastric resection |
|
Definition
| in antrum is removes, H secretion may over decrease causing gastric mucosa atrophy |
|
|
Term
| what are the other names for heartburn |
|
Definition
| acid reflux, GERD, gastroesophageal reflux disease |
|
|
Term
| what are the causes and effects of heartburn |
|
Definition
abnormal lower esophagel concentration and slow stomach emptying, incomplete closure of LES allowing regurgitation of gastric contents into esophagus, hiatial hernia
effects: wall becomes hyperemic (blood flow increases, iflammation) and white patches are seen (leukoplakia), simple squamous epithelium of low esophagus is replaced by columnar which is at risk for adenocarcinoma, heartburn, regurgitation, nausea, dysphasia (difficult swallowing) |
|
|
Term
| what are the types of hemmhorids, what distinguishes them |
|
Definition
internal: superior to pectinal line
external: inferior to pectinal line |
|
|
