Small Intestine Structure and Function Flashcards
3 main parts of small intestine
duodenum, jejunum and ileum
main role of small intestine
absorption
what does each part of the small intestine absorb most
- duodenum - iron
- jejunum - nutrients
- ileum - H2O and NaCl
pit that sits next to a villus
crypt
what do crypt cells do
secrete water and chlorine
how does the intestinal epithelium move H2O in from the lumen
by moving in Na with absorption of nutrients like glucose and amino acids to produce a concentration gradient which pulls the water across
what lymph structure runs up the middle of a villus
a lacteal
how do crypts secrete water into the lumen
by actively pumping chlorine across and creating a concentration gradient
why secrete water
- keep the lumen contents liquid
- aid mixing
- aids nutrient presentation to absorbing surface
- washes away potentially harmful substances
what structure increase surface area in the intestine
plica –> villi –> microvilli
two types of intestinal motility
segmentation and peristalsis
difference between segmentation and peristalsis
segmentation is contraction and relaxation creating short intestinal segments
peristalsis is like this but one contraction moving in a wave
what cells produce the BER
pacemaker cells
what is the basic electrical rhythm
spontaneous re and depolarisation by the pacemaker cells in the longitudinal muscle layer
action potential frequency determines the _____ of contraction
strength
