GI 1 Flashcards
inhibitory hormones for small bowel peristalsis
secretin and glucagon
caused by intense irritation of intestinal mucosa; involves ANS, brainstem, myenteric plexus (long distances of small bowel covered in minutes)
peristaltic rush
stimulates gastric acid secretion and gastric mucosal growth
gastrin
mediates feedback control of ileocecal sphincter (intensifies when cecum is distended)
myenteric plexus and prevertebral symp ganglia
what pyrloic glands secrete
mucous and gastrin
colonoileal reflex is important for this
inhibits ileal release
what Ach stimulates secretion of
pepsinogen, HCl, mucous
how much bile salts produced per day
6 gm
sympathetic inhibits or activates mucous protection/secretion?
inhibits
frequency of normal small bowel contractions (less than this number typically)
12/min
intensifies peristalsis in ileum (immediately after meal), empties ileal contents into cecum
gastroileal reflex
where most bile salts are reabsorbed
terminal ileum
where secretin is produced
S cells duodenum
occurs during distension of small bowel, acid in upper small bowel, protein breakdown products, or irritation of mucosa (inhibits gastric secretion)
reverse enterogastric reflex
actually excite the muscle contraction; complex interactions among SMC and interstitial cells of Cajal
spike wave
in proximal duodenum…part of small bowel secretion
Brunner’s glands
pits in small intestine (line surface area)
crypts of lieberkuhn
works to neutralize the HCl emptied into the duodenum from the stomach
HCO3
amount of bile produced per day
600-1000 mL
ions present in saliva
K, bicarbonate, Na, Cl
responsible for bile acid secretion
secretin
GI glands release this for vasodilation
kallidin and bradykinin
small bowel digestive enzymes (6)
peptidase, sucrase, maltase, isomaltase, lactase, intestinal lipase
absorbed at terminal ileum
bile acids and folate
released by parasym…excites secretion of pepsinogen, HCl, and mucous
acetylcholine
where cholecystokinen is produced
I cells duodenum/jejunum
enteric NS plexus located between longitudinal and circular muscle layers
myenteric/Auerbach’s plexus
cranial nerves that transmit information from reticular substance medulla/pons for swallowing
V, IX, X, XII
three stages of swallowing
voluntary, pharyngeal, esophageal
enzyme that splits fatty acid from phospholipids (pancreatic secretion)
phospholipase
what temporarily stores 1/2 to 3/4 of nutrients
liver sinusoids
what makes up most gallstones
cholesterol
branch of NS that promotes propulsion
parasym
hormones that act as vasodilator substances to increase splanchnic blood flow (4)
CCK
vasoactive intestinal peptide
gastrin
secretin
where enterochromaffin like cells located
in the recesses of oxyntic glands
(or fundic/gastric glands)
inhibits gastric acid secretion in duodenum; promote pancreatic secretion of bicarbonate (to neutralize acid)
secretin
what intrinsic factor is necessary for (activated by HCl)
absorption B12
how much HCl per L of gastric juice
160 mmol
final secretion from canaliculus includes these substances
water, HCl, KCl, NaCl
what ptyalin digests
starch
what tubular glands secrete (in stomach and upper duodenum)
pepsinogen and acid
how long mass movements usually persist
10-30 min
where gastrin is released
G cells
where tubular glands are located
stomach and upper duodenum
amount of chyme that empties into cecum per day
1500-2000 mL
transmits wave of relaxation preceding peristalsis
myenteric inhibitory neurons
from stomach and colon..inhibits gastric motility and secretion
enterogastric reflex
remove bacteria and harmful matter from splanchnic circulation
reticuloendothelial cells
promotes UGI motility
motilin
inhibits increased stomach motility caused by gastrin
CCK
principal glands for salivation
parotid, submandibular, sublingual, buccal
micelles of bile salts aid in absorption of these
fatty acids, monoglycerides, cholesterol, other lipids
calories consumer per liter of gastric juice produced
1500
cells that make up oxyntic gastric glands
mucous neck cells, peptic/chief cells, parietal/oxyntic cells
what oxyntic glands secrete
HCl, pepsinogen, intrinsic factor, mucus
stimulate pancreatic digestive enzymes
Ach and CCK
stimulates gallbladder emptying; inhibits gastric contraction; and possibly inhibits hunger (respond to fats, FA, monoglycerides)
CCK
factors in the saliva that destroy bacteria
thiocyanate ions, proteolytic enzymes/lysozyme
reflex involved in gastric phase of gastric secretion
vasovagal
function of proximal colon
absorption of water and electrolytes
drug that will weaken segmented contractions (by blocking excitatory activity of enteric NS)
atropine
located between the intestinal vili; contain goblet cells and enterocytes
Crypts of Lieberkuhn
where H. pylori is typically located
antrum
what goblet cells secret in Crypts of Lieberkuhn
mucus
small bowel digestive enzyme important for splitting neutral fats into glycerol and FA
lipase
enteric NS plexus that controls GI movements; increased tone, intensity of contraction, rate of rhythm, velocity of conduction
myenteric
slow closing/opening channels in GI muscle fibers responsible for action potentials
Ca/Na channel
important in “mass movements”; 20 cm distal to this point lose haustrations and contract as one unit, propelling feces (lasts 30 sec…relax for 2-3 min)
constrictive ring
what produces gastrin?
G cells
(in antrum of stomach)
intraluminal pressure of lower esophagus
30 mmHg
inhibits gastric motility; stimulates secretion of insulin by the pancreas
GIP
enteric NS plexus located in submucosa; receives signals about what should be done
submucosal/Meissner’s
hormones that inhibit gastric secretion
secretin, gastric inhibitory factor, vasoactive intestinal polypeptide, somatostatin
3 routs that food in duodenum increases pyloric sphincter tone
enteric NS, extrinsic n to prevertebral ganglia, vagus/brainstem
where sensory nerve endings in GI epithelium send their afferent fibers
enteric plexuses, prevertebral ganglia sympathetic, spinal cord, vagus nerves
direct release of HCl is directly dependent on the amount of this secreted
histamine
enteric NS plexus that controls GI secretion and local blood flow; intestinal secretion, absorption, contraction that causes infolding of mucosa
submucosal
length of primary peristalsis
6-10 sec
splits small peptides into amino acids (small bowel digestive enzyme)
peptidase
performs hydrolysis of cholesterol esters (pancreatic secretion)
cholesterol esterase
hormone that reduces blood flow to splanchnic system
somatostatin
GI hormone that is important in small bowel secretion
secretin
function of distal colon
storage fecal matter
strongly stimulate secretion of acid by parietal cells
gastrin and histamine
activates trypsin; secreted by intestinal mucosa when exposed to chyme
enterokinase
NS responsible for reverse enterogastric reflex
myenteric NS, extrinsic sym and vagus
cells that secrete histamine
enterochromaffin-like cells
most potent emptying of gallbladder
CCK
protein present in mucus secretion (lubricates and protects surface)
mucin
enzyme that catalyzes conversion of OH- to form CO2
carbonic anhydrase
reflexes that facilitate mass movements
gastrocolic and duodenocolic
what parietal cells secrete
HCl
pH of stomach due to HCl acid secretion
0.8
rate of movement for small bowel peristalsis (3-5 hours transit)
1 cm/min
fluid and dissolved substances are absorbed until this amount of feces are expelled (important for diagnosis diarrhea)
80-200 mL
usual stimulus for intestinal peristalis
distension of gut
threshold for spike wave
-40
length of GI spike (time)…10-40x longer than nerve fiber; 1-10 spikes per second
10-20 msec
more abundant form of gastrin
G17
enzyme that hydrolyzes neutral fat into fatty acids and monoglycerides (pancreatic secretion)
pancreatic lipase
sensory cranial nerves involved in initiating pharyngeal stage of swallowing
V and IX
stimulates secretion of histamine
gastrin
stimulates gastric HCl secretion
gastrin
reflex for evacuation
gastrocolic reflex
alpha-amylase that is present in serous secretion
ptyalin
cells in crypts of Lieberkuhn that secrete water and electrolytes; also absorb water, electrolytes, nutrients
enterocytes
where motilin is secreted (during fasting)
stomach and duodenum
regulates small intestine secretion (NS)
local enteric nervous reflexes
what pancreatic amylase breaks down
starch, glycogen, CHO