motility
the ability to mix contents and move them from the oral to anal end of the GI tract by muscular contractions
absorption
transport of molecules across epithelial membranes into the body fluids
chyme
mixture of partially digested food and digestive juices that passes from the stomach into the duodenum
peristalsis
waves of smooth muscle contraction
serves to propel the contents of the digestive tract in one direction
segmentation
major contractile activity of the small intestine
bilirubin
yellow substance resulting from heme breakdown
excreted in bile as a bile pigment
gives waste its color
enterohepatic circulation
recirculation of a compound between liver and small intestine
heptocytes
liver cells
digestion
process of converting food into molecules that can be absorbed through the intestine into the blood
H/K ATPase pump
transport H+ against concentration gradient into the stomach while transport K+ in opposite direction
bile salt
act to emulsify fat in the lumen of the small intestine
micelles
colloidal particle formed by the aggreggation of numerous molecules
amylase
digestive enzyme of carbohydrates
trypsin
protein digesting enzyme
lipase
digests triglycerides
emulsification
process of producing an emulsion derived from fat globules
accessory digestive organs
liver
gallbladder
pancreas
overall function of digestive system
process ingested foods into molecular forms and transfer, with water and salts, to the circulatory system
systems working with digestive
cardiovascular
muscular
nervous
respiratory
urinary
smooth muscle function in D.S.
mix luminal content and move contents from mouth to anus
propulsion
swallowing
peristalsis
mechanical digestion
chewing
churning
segmentation
chewing
voluntary control of jaw muscles in addition to rhythmic chewing motions caused by the pressure of food against the gums, hard palate, and roof of the mouth and tongue
chewing involves
skeletal muscles
smooth muscles
neural activity
pressure receptors stimulated by food on the pharyn send…
afferent impulses to the medulla oblongata
efferent fibers tell muscles of pharynx and esophagus to
swallow
soft palate prevents
food from entering the nasal cavity
epiglottis
covers glottis to prevent aspiration
once food is in the esophagus…
upper sphincter closes and waves of muscle contractions move food downward
peristaltic waves
contraction of the muscles surrounding a tube
once food is through the esophagus….
the lower esophageal sphincter closes
stomach
store
dissolve
partially digest macromolecules in food
regulate rates entering small intestine
acidity in stomach kills bacteria entering with food
rhythmic peristalsis in stomach are timed by
pacemaker cells
stomach cells secrete
2 liters of HCl per day
----- gets pumped into stomach as well as -----
H+
Cl-
liver serves as
secretory organ
filter and functions in the removal of old red blood cells
liver major function
secrete bile
liver also
processes and stores nutrients
hepatic portal system
specialized vasculature that delivers absorbed nutrients to the liver for processing before they enter the general systemic circulation
nutrients are absorbed from----- and carried via capillaries to the ------
small intestine
hepatic portal vein
gallbladder
stores and concentrates bile
bile enters from the ---- and exits to the ----- via the -----
liver
duodenum
common bile duct
when the ---- is empty of food, the ---- closes
small intestine
common bile duct
pancreas
produces “pancreatic juice”
rich in bicarbonate and digesting enzymes
bicarbonate in the pancreas functions to
neutralize acid entering duodenum from stomach
the ----- and ------ join the common bile duct from the liver before entering the duodenum
bile duct
pancreatic duct
most material in small intestine is digested and absorbed due to
high absorptive surface area of small intestine
enzymes in small intestine break down food into
monosaccharides
fatty acids
amino acids
nucleotides
after a meal is mostly absorbed…
the migrating myoelectrical complex replaces segmentation
the migrating myoelectrical complex
moves undigested material into large intestine
large intestine
primarily stores/makes feces
small amount of fluid absorption
houses a variety of gut microflora
gut microflora
converts indigestible polysaccharides into short chain fatty acids for absorption