Absorption Flashcards
(22 cards)
brush border of intestine
finger like protrusions on each cell to increase surface area
contains disaccharidases and proteases
roles of pancreas
secretion of bicarbonate pancreatic juice neutralises chyme
proteases
pancreatic lipase
function of gall bladder
storage and concentration of bile for digestion of lipids
function of bile
neutralise chyme
function of bile salts
emulsify lipids
function of liver
secretion of bile
processing of absorbed nutrients
components of bile
bile salts
phospholipids
HCO3-
also cholesterol, trace metals and bile pigments removed from the blood
glucose v fructose transporter in brush border of intestine
SGLT1
GLUT 5
glucose and fructose transporter between intestinal cells and blood
GLUT2
incretin effect
ingestion of glucose>as glucose passes through GI tract cells release incretin hormones (GLP-1 and GIP) that stimulate insulin secretion from pancreas
infusion of glucose into blood>no incretin hormone release
GIP
stimulated by nutrients in small intestine
secreted by K cells in duodenum and jejunum
stimulates insulin secretion
incretin hormone
GLP-1
stimulated by nutrients in small intestine/incretin hormone
secreted by L cells in ileum
promotes insulin release
inhibits glucagon release
delays gastric emptying
suppresses appetite and energy intake
process of fat breakdown
emulsification by bile salts
hydrolysis by lipase
temporary storage as micelles
transport into lumenal epithelial cells
re-esterification to TAGs
packaged as chylomicrons
enters lymphatic system
segmentation
responsible for motility in small intestine
more peristalsis
contraction and relaxation of longitudinal muscles
gastroileal reflex
Segmentation increased in the ileum with gastric emptying
Once the majority of the meal has been
absorbed, segmentation is replaced with
peristalsis
Migrating myoelectric complex (MMC)
Moves undigested material to the large intestine
Prevents bacteria from remaining in the small intestine too long
functions of large intestine
Primarily storage of material prior to defacation
Some digestion of undigested material (via
bacteria), eg fibre
Fluid absorption concentrates fecal matter
Ileocecal sphincter
large intestine motility
opens to allow chyme through when ileum contracts
closes when large intestine distends
how are fat soluble vitamins absorbed
emulsification
how are water soluble vitamins absorbed
diffusion or mediated transport
During the absorptive state, the primary source of energy for liver cell function is
keto acids derived from amino acids
acids enter the krebs tricarboxcylic acid cycle and are catabolized to provide energy for the liver cells
Ketone bodies derived from fatty acids provide an important energy source during
fasting
