GI Phys. & Metabolism

hrdcorhrvivor's version from 2017-05-13 06:14

Section 1

Question Answer
which division of the PNS controls GI systementeric nervous system
primary jobs of the GI systemobtain nutrients from the environment, break down food into absorbable units, absorb these smaller units, respond change and adjust to different foods
the 6 digestive processes1. ingestion 2. secretion 3. propulsion and mixing 4. digestion 5. absorption 6. elimination
ingestion detailedmove food into the digestive tract
secretion detailedexocrine secretions into digestive lumen, promotes digestion, adjust tonicity, lubrication. endocrine secretion into blood stream. control motility/contraction and secretions, food intake and energy
propulsion and mixing detailedmuscular activity of digestive tract, SM, peristalsis throughout and segmentation in small intestine
digestion detailedbreakdown of complex food into small units. mechanical and chemical. carbs: monosaccharides (glucose, fructose). proteins:single amino acids or di/tripeptides. fats: free fatty acids & monoglycerides.
absorption detailedsmall units resulting from digestion, along with water, vitamins, electrolytes transferred from digestive tract lumen into blood/lymph. mainly small intestine
elimination detailedundigested, unabsorbed waste
accessory organs salivary glands, liver, gall bladder, pancreas
4 tissue layers of digestive tractserosa, muscularis, submucosa, mucosa
no food in the lumenpacemaker cells oscillate, basic electrical rhythm in stomach. migrating motility complex: contractions frequent enough to move residual stomach/small intest contents to large intest
food in lumenstretch &peptides in the stomach and small intest activate neural circuits that increase amplitude and frequency of BER, SM spike and contract, increase digestive tract motility
short reflexoriginates in ENS, submucosal and myenteric plexus
long reflexintegrate in CNS, PSNS: excites and enhances GI function via vagus nerve SNS: inhibits GI function except salivation
phases of digestion 31. cephalic phase: smell, sight, thought of food stimulates salivation and secretes gastric juice. 2. gastric phase: gastric secretion cont. & movement of stomach increased to promote entry of chyme into small intest. 3. intestinal phase: events slow the exit of chyme from stomach cont. digestion
oral cavitychewing: mechanical digestion, mixes with saliva. salivary glands: chemical digestion, contains mucous, lysozyme, amylase
pharynxhouses esophagus. swallowing reflex: all or none, initiated when food is forced by tongue to pharynx. GERD: gastrointestinal reflux disease
stomachregions: fundus, cardia, body, pylorus. 3 funx: store ingested food until it can be emptied into small intestine, secretes HCl and enzymes that begin protein digestion, mixing to make chyme
gastric mucosaoxyntic mucosa: fundus and body. pyloric gland area: pylorus
parietal oxyntic cellssecrete HCl and intrinsic factor (helps with B12). funx: activates zymogen pepsinogen into active pepsin, denatures protein, kills microbes
enterochromaffin like cells ECLsecrete histamine. funx: activates parietal cells
mucous cellsline gastric pits and entrance of glands, secrete thin, watery mucous. funx: protects stomach from acidic chyme and enzymes
chief cellssecrete enzyme precursor pepsinogen. funx: with HCl, it turns it into pepsin
G cellssecrete gastrin into bloodstream, stimulates parietal, chief, and ECL cells. increases gastric motility, movement of undigested material into large intest
D cellssecretes somatostatin into bloodstream, inhibits parietal, chief, and ECL cells
stimulates secretions cephalic phase (long reflex): seeing smelling. gastric phase(short reflex): distension. both stimulated by vagus nerve
inhibits secretionsremoval of peptides and sitension as stomach empties, accumulation of acids
4 aspects of gastric motility1. filling: receptive relaxation, eating, mediated by vagus nerve. in stomach 3.mixing:pylorus of stomach 4.emptying: in duodenum
factors of gastric emptying in duodenumfats: when entering, further entry of fats is prevented. acid:unneutralized acid inhibits emptying. hypertonicity: emptying inhibited as osmolarity content rises. distension: too much chyme inhibits emptyting
neural response to gastric emptyingtriggered by intrinsic nerves and autonomic nerves, enterogastric reflex
hormonal response to gastric emptyingrelease of secretin and cholecystokinin CCK into duodenal mucosa

Section 2

Question Answer
3 segments of the small intestineduodenum, jejunum, ileum
functions of the small intestinemixes chyme with digestive juices, increased exposure of chime to absorptive surfaces, propulsion down GI tract
enterocytesepithelial cells of small intestine, apical surface faces lumen and contains microvilli (brush border), basolateral surface faces capillaries, crypt of lieberkuhn is where theyre made, secretes ions and water into lumen
pancreatic juicesodium bicarbonate: from duct cells, neutralizes stomach acid. proteolytic enzymes: from acinar cells
trypsinogenfrom acinar cells, converted to active form trypsin by enterokinase
chymotrypsinogenfrom acinar cells, converted to active form of chymotrypsin by trypsin
procarboxypeptidasefrom acinar cells, converted to active form of carboxypeptidase by trypsin
secretinfrom S cells, increased secretion of sodium bicarbonate from pancreatic duct cells
CCKfrom I cells, secretion of digestive enzymes from pancreatic acinar cells
liverproduction of bile salts. indirect with digestive system: detoxification, synthesis of plasma proteins
bilesecreted by liver, stored by gall bladder. bile acids/salts, cholesterol, bilirubin, bicarbonates. emulsification: neutralizes stomach acids. stimulated by CCK
carbohydrate digestionstarch and carbs are broken down into disaccharides via salivary amylase and pancreatic amylase. absorption via secondary active transport, GLUT 2 (glucose and galactose) and GLUT 5 (frutcose)
protein digestion broken down into peptides and amino acids by pepsin and proteolytic enzymes from pancreas. small peptides transported into cell, absorbed into bloodstream through faciliated diffusion
fat digestionemulsified in bile salts and pancreatic lipase into monoglycerides and free fatty acids (micelles) micelles enter enteroccytes through simple diffusion. resynthesized into triglycerides. packages to form chylomicrons with cholesterol and phospholipids.
large intestine consists ofcecum, ascending, transverse, decending, sigmoid colon, rectum.
gastrocolic reflexmediated from stomach to colon by gastrin and ANS
defecation reflexfeces moves down rectum, stimulating stretch receptors, spinal reflex initiated PSNS motor fibers contract rectum relaxing internal anal sphincter, external anal sphincter relaxes
stored fuel in the body1. carbohydrates, essential for the brain. 2. fats, most energy stored here, energy during fasting. 3. proteins, last resort for energy, soruce of glucose for brain during fasting
fed stateabsorptive state, more anabolic reactions, glucose plentiful, more insulin.
fasting statepostabsorptive state, more catabolic reactions, energy stores used, more glucagon
GLUT 4skeletal muscle and adipocytes
GLUT 3neurons
GLUT 1blood brain barrier
glycogenesisformation of glycogen from sugar
glycogenolysisbreakdown of glycogen

Section 3

Question Answer
GI mucosa epiprotection, absorption, secretion
GI mucosa lamina propriaCT, contains BV, lymph vessels, mucosa-associated lymphatic tissue MALT
GI mucosa muscularis mucosaecreates folds to increase surface area
GI submucosaareolar CT, BV and lymph vessels, submucosal plexus: neuronal network part of ENS
GI muscularispharynx, upper portions of esophagus, ext anal spincter (skel muscle), everything else is sm, myenteric plexus is between muscle layers
GI serosaoutermost layer, areolar CT and simple squamous, aka visceral peritoneum, esophagus lacks serosa, adventitia
visceral peritoneumcovers some organs, aka serosa
parietal peritoneumlines wall of cavity
peritoneal cavityspace between visceral and parietal peritoneum
5 major peritoneal foldsgreater omentum, lesser omentum, falciform ligament, mesentary, mesocolon
oral cavity properfrom gums and teeth to fauces (opening between oral cavity and oropharynx)
hard palateant portion, maxillae and palatine bones
soft palatepost portion, muscular partition between oro and nasopharynx
parotid salivary glandinf and ant to ears
submandibular salivary glandfloor of mouth
sublingual salivary glandbeneath tongue, sup to submandibular
extrinsic muscles of tonguestyloglossus, genioglossus, hyoglossus
intrinsic muscles of tonguetransverse, longitudinal, vertical
lungual frenulumattaches tongue to floor of oral cavity
periodontal ligamentattaches teeth to socket
3 regions of teethcrown: visible, root: below gums, embedded in bone, neck: junx of root and crown at gum line
dentincalcified CT, covered with enamel
incisors4, used for cutting food
caninestear and shred food
premolarstwo sets, crushing and grinding
molars3 sets, wisdom teeth

Section 4

Question Answer
esophagussecretes mucous and transports food to stomach, no serosa has adventitia, passes through esophageal hiatus at diaphragm
stomach muscularislongitudinal, circular, oblique muscles
main pancreatic ductlargest, meets common bile duct
accessory pancreatic ductsmallest
islets of langerhansendocrine, secrete glucagon, insulin
liver hepatocytesmajor funx cells of liver, metabolic, secretory, endocrine funx. produce bile.
bile canaliculicollect bile from hepatocytes
hepatic sinusoidscapillaries between hepatocytes
portal triadbranch of hepatic artery, bile duct, and branch of hepatic vein
gallbladderstores and concentrates bile produced by hepatocytes
small intestine absorptive cellsdigestion and absorption
small intestine goblet cellssecrete mucous
small intestine intestinal glandssecrete intestinal juice
small intestine duodenal glandsalkaline mucous (neutralizes contents from stomach)
large intestine mucosamostly goblet and absorptive cells, no circular folds, microvilli
large intestine muscularislongitudinal muscle modifies to form taenia coli, form haustra (pouches)