what are accessory organs? Examples?
secrete contents into lumen of gut; salivary glands, liver, gallbladder, pancreas
what are the 3 salivary glands?
parotid, sublingual, submandibular
liver secretes these things
bile acids, bicarbonates
stores liver secretions
gallbladder
pancrease secretes pancreatic enzymes and bicarbonates into ___
duodenum
three parts of small intestine:
duodenum–>jejunu–>ileum
these bacteria contribute to digesting fibre, provide essential nutrients, prevent pathogenics from colonizing
commensal
these increase growth of commensal bacteria
probiotics
separate portions of GI
sphincters
mjority of absorption take place in
duodenum of small intestine
___part of anus is made up of skeletal muscle
external
myenteric and submucous plexuses involve ______
nerve ganglia (enteric nerves)
deep muscular plexus located in ____ muscle layer
circular
pacemakers found in ___ and ___ plexuses
myenteric; deep
what are the 5 hormones secreted by endocrine cells?
gastrin, CCK, secretin, GIP, motilin
outer connective tissue covering the digestive tract that secretes watery fluid for lubrication
serosa
this layer of GI is where blood and lymph vessels reside, responsible for distensibility and elasticity
submucosa
sympathetic and parasymp activity is example of ___ innervation, enteric nervous sys (nerve plexuses) is example of ___
extrinsic; intrinsic
slow wave potential is also known as:
Basic Electrical rhythm
ICC connected by ____, to allow ____
gap junctions; syncytium
destruction of ICCs in ___ leads to impaired gastric motility, called:
diabetes; gastroparesis
what are the ICC functions?
generate slow wave activity, coordinate active propagation of slow waves, transduce motor neural inputs from ENS to muscle, sense stretch
a receptor-type tyrosine kinase binding to ligand stem cell factor
c-kit
ICCs in stomach beat __ waves/min, in duodenum __ waves/min
3; 12
challenges in GI?
- moving food down tube at appropriate speed without blockage
- digest food without digesting self
- match fluid input/output
- keep bacteria/viruses from entering
how does GI keep bacteria/viruses enter body?
oral cavity sanitizes; ilium of sm intestine proliferate good bacteria which is colonizing large intestine
___ L of fluid/day enter small intestine from ingestion and GI secretions of water
7-10
malabsorption of electrolytes and water in sm intestine lead to _____
diarrheic stool
motility requires ____ and ___ for muscle contraction
ICCs; enteric nerves
major functions of digestive sys?
mvmt/mixing thru alimentary tract, secrete digestive juices/digestion, absorption, circulation blood carry away nutrients, nervous/hormone reg, mucosal immune function, excretion
___ system uses hormonal and neurotrans communication methods with ____
endocrine; stomach
this part of GI referred to as “reservoir”
large intestine
friendly bacteria reside here
appendix
GI is ___ to external enviro
continuous
equation of energy balance?
food intake-energy loss = energy expenditure
molecules are broken down by ___
hydrolysis
nutrients are extracted by __ and ___ digestion
mechanical; chemical
stim depolarization of basal membrane by:
stretch, acetylcholine, parasymp
inhibit basal membrane potential by:
norepinephrine, sympathetics, nitric oxide, VIP
VIP stands for:
Vaso-active Intestinal polypeptide
what are the diff motility patterns?
peristalsis, segmentation, mass mvmt, migrating motor complex
peristalsis occurs in __
esophagus
motor pattern involved with fasting, and stimulated by increase in levels of motilin
migrating motor complex
proteins/electrolytes contained in saliva
lingual lipase, amylase, mucins, IgA, lysozyme, lactoferrin, bicarbonate
you secrete about ___mL saliva per day
1500
parasympathetic input to salivary glands causes _____, sympathetic input causes _____
abundant flow; mucus enrichment (less flow)
damage to ____ cause atrophy in salivary glands
parasymp
damage to salivary glands referred to as:
xerostomia
v salivary secretion caused by:
sleep, fatigue, dehydration, fear
what drugs can inhibit salivary gland secretion?
antidepressants, antihypertensives, psychotropics
syndrome involving autoimmune attack of salivary glands
Sjogren’s syndrome
condition characterized by difficulty in swallowing, food getting stuck, and reduced inhibitory nerve input
achalasia
relaxation mainly due to ___, contraction by ____
NO; ACh
what is GERD?
gastroesophageal reflux disease; characterized by esophagitis, columnar cells replace squamous epithelium, adenocarcinoma
GERD treatments?
proton pump inhibitors, H2 histamine receptor antagonists
How is primary peristaltic wave initiated? How is secondary initiated?
swallowing centre (medulla); distension
functions of stomach?
store ingested food, secrete HCl and enzymes begin protein digestion,
where is gastrin secreted?
from endocrine cells called G-cells in antrum (pyloric gland)
where is ghrelin secreted?
oxyntic gland
mix and pulverize food
antral pump
receptive relaxation mediated by ___ is responsible for constant ___
NO; pressure/volume
stomach can extend to about ____ L
1
storage involves weak mixing in __ and __
fundus; body
mixing involves strong ___ peristaltic contractions
antral
___ hormone increases contractility of antral smooth muscle
gastrin
presence of ____ shut down gastric emptying in a negative feedback loop; this is called ___ reflex
gastric chyme in duodenum (decreased pH), presence of lipids, osmolites, distension in duodenum; enterogastric
neural and hormonal factors in enterogastric reflex?
secretin (acid), cholecystokinin (fats), GIP (gastric inhibitory peptide–>osmolarity change, carbs)
GIP promotes release of ___ from pancreatic __ cells
insulin; beta
gastric enzymes such as ____ are secreted from oxyntic mucosa
pepsinogen (inactive form of pepsin), gastric lipase
ghrelin and gastrin are secreted into ___
blood
____ cells are responsible for acid secretion and intrinsic factor
parietal
intrinsic factor is important for ____
blood development
___ cells are responsible for release of pepsinogen, gastric lipase
chief
mucus created by surface ___ and neck ___ cells
epithelium; mucous
stem cells replenish epithelial cells every ____ days
3-4
functions of HCl:
digestion, activate pepsinogen, kill bacteria
function of intrinsic factor
Vit B12 absorption (cobalamine), lack leads to pernicious anemia
HCl and intrinsic factor are secreted by:
parietal cell
parietal cells have lots of ___
mitochondria (ATP to drive proton pump), tubulovesicles (H/K ATPase)
activation of acid secretion is by ____
histamine, acetylcholine, gastrin binding to respective receptors at basolateral membrane
IF and acid secretion increases with the fusion of ___ and ___
tubulovesicles; intracell canaliculi
what is alkaline tide?
at max acid secretion, bicarbonate in blood supply of stomach
what are three phases of gastric secretions?
cephalic influences, gastric phase, intestinal phase
cephalic contribute __% total acid secretion, gastric __%, intestinal __%
30; 50; 5-10
enzymes in ___ not essential for life, enzymes from ____ are essential
stomach; pancreas
how does stomach not destroy itself with strong acid?
tight junction provide barrier and prevent leakage, luminal mem not permeable to H, layer of mucus offer protection (has bicarbonate), damaged cells rapidly replaced every 3 days
breakdown of the mucosal barrier results in a ____
peptic ulcer
wht causes peptic ulcers?
H. pylori, chem exposure, stressful situations (^ gastric secretions)
how to cure h. pylori peptic ulcer?
antibiotic+proton pump inhibitor
gastric secretion during intestinal phase is inhibited by presence of _____ or _____
lipids; low pH
what are secretions by the small intestine?
mucus and water, GI hormones, lysozyme, no digestive enzymes (except enterokinase)
secretin acts on ____ to secrete
pancreatic ducts; bicarbonate
enterokinase is a _____ enzyme
brush border
enterokinase cleaves __
trypsinogen
“the master enzyme” for all pancreatic proteases
trypsin
primary bile acid comes from____
cholesterol (made in liver hepatocytes)
secondary bile acid comes from ____
colonic bacteria enzymes
primary bile acids are conjugated with ____
taurine, glycine
what are the two types of gallstones?
Ca bilirubenates, cholesterol stones (most common)
what are factors that promote formation of gallstones?
bile stasis, chol. supersaturation in bile, nucleation factors
symptoms of gallstones?
pain below right scapula after eating oily/fatty meal
process where fat globs are turned into droplets so that there’s more SA for pancreatic lipase to act
emulsification
bile secrete ___g bile per day
0.2
need ___ to absorb vit ADEK
bile salts
what does asbt stand for?
apical sodium dependent bilesalt transporter
asbt found at ____
terminal ileum
asbt is important for ____ circulation
enterohepatic
colonic bacteria do these two things to bile salts:
1) deconjugate bile salts
2) remove hydroxyl radical
fat malabsorption results in:
diarrhea
aggregates of bile salts is called:
micelles
production of bile is ^ by:
secretin, stim of vagus nerves
circular folds in small intestine called:
plicae circularis
most absorption happen at ____, most secretion at ___
villi; crypts
small lymphatic vessels are called:
lacteals
villi, crypts, plicae circularis, microvilli on apical mem of sm intestine ^ SA by ___x
600
“the body’s biochem factory”
liver
enzyme that resumes fat digestion by positioning lipase near O/W interface
colipase
blood supply to liver ___% from hepatic portal vein, ___% from hepatic artery
75; 25
hepatic portal vein and artery blood mix at ____
hepatic sinusoids
majority of cells in liver are:
hepatocytes
these cells store vit A
stellate cells
cells that are phagocytic immune cells
Kupffer cells
hepatic artery, hepatic portal vein and bile duct form the _____
hepatic portal triad
things that come into liver from portal vein?
bile salts, nutrients, drugs, foreign substances
things that come into liver from hepatic artery
O2, nutrients, bilirubin, hormones, drugs
things that come out of liver thru bile
bile salts, bilirubin, water/ions, cholesterol
things that come out of liver thru hepatic vein
glucose, plasma proteins, urea, vit. D, metabolites
what does liver store?
glycogen, fats, Fe, Cu, vitamins
liver synth plasma proteins such as
albumin, clotting factors
“fuzzy coat” of sugar moieties, glycosylated proteins
glycocalyx
pancreatic amylase digests starch into ______
maltose, maltriose, short oligos
sugars are digested by ____
brush border enzymes in microvilli of small intestine
examples of brush border enzymes?
sucrase, isomaltase
gluc and gal are transported by ______ carrier protein; it is a ____ active transporter
SGLT-1; secondary
fruc absorbed by ___ which is a _____ transport process
GLUT5; passive
basolateral membrane has GLUT ___ and GLUT ___
2; 5
what does PEPT1 transport?
di-tri peptides, along with H+ ion
3 regions of large intestine?
ascending, transverse, descending
first part of colon??
cecum
discontinuous longitudinal muscle in large intestine is called:
tenia coli
mucosal folds in large intestine called:
haustra
motility of large intestine includes:
haustral contractions, mass mvmts
point of appendix?
refresh bacteria in colon ater large bouts of diarrhea
motility dysfunction in colon characterized by severe constipation, dilation of colon, no myenteric plexus ganglion
mega-colon-Hirschprung’s disease
two defecation reflexes:
intrinsic (weak), parasymp (strong)
in defecation reflex, there is ___ of rectum and relaxation of _____
contraction; internal anal sphincter
parasymp reflex in ____ nerves
sacral, pelvic
what is the largest lymphoid organ in body?
gut-associated lymphoid tissue
lymphoid nodules in the submucosa connective tissue are called:
Peyer’s Patch
associated with colon cancer
polyps (tubular adenoma)
symptoms of polyps?
blood in feces, diarrhea
bacteria in large intestine convert bilirubin to ____
stercobilin
normal range of glucose in plasma?
3.9-6mmol/L
liver shuttles XS gluc into _____, and turned into ____
hepatocytes; glycogen
short term regulation of hunger is provided by _____
GI hormones
long term regulation of hunger is provided by ______
leptin and insulin
inhibitory signals for eating?
leptin, insulin, PYY, CCK
leptin acts on _____ nucleus of hypothalamus by decreasing release of ___ and _____ protein
arcuate; NPY; agouti
leptin stimulates release of ___
MSH (melanocyte stimulating hormone)
insulin stimulates ___ storage and increases ___ secretion; suppresses ___ release in hypothalamus
fat; leptin; NPY