Intestines Flashcards
where is the last stage of food breakdown
digestion on wall of small intestine
what are the enzymes that are involved in the food breakdown at the small intestine
enterokinase
disaccharidases
aminopeptidases
what does the enzyme enterokinase do
activates trypsinogen
what does the enzyme disaccharidases do
completes carbohydrate digestion
what does the enzyme aminopeptidases do
complete protein digestion
how does the small intestine contribute to digestion
absorption of nutrients into blood stream
during peristalsis longitudinal and circular muscles in SI wall contract to push food down tract
where are nutrients absorbed at the small intestine
absorb nutrients through microvilli (and villi)
then absorption across villi walls to the enterocytes to be absorbed into bloostream
how long o enterocytes live for
2-3 days
how are enterocytes replaced
constantly replaced by differentiation of simple cells from crypts of LieberKuhn (glands at villus base)
what do the enterocytes develop during differentiation
brush boarer (microvilli)
digestive enzymes
transporter proteins
what does the villus have
possess nerve supply and motile cells
how is the contents in the small intestine mixed
villi can sway, mix contents gain access to all nutrients
increases blood flow and lymph - enhance absorption
what is the motor activity of intestines effect
propulsive movement - shifts material along gut (peristalsis)
mixing movements - mixes digesta with secretions ensures material close to absorptive surface
what processes occur during motor activity of intestines
segmentation
pendular movements
retroperistalsis (large intestine only)
what occurs during peristalsis in the motor activity of intestine
motor program coordinated by enteric nerves
stimulus causes circular muscle infront of digesta (anal side) to relax due to inhibitory neurone activation
contraction of circular muscle behind it (oral side) ue to excitatory neurone activation
process continues till digesta doesn’t provide sufficient stretch
