Intestinal phase: vasoactive intestinal peptide (3 things)
activated by chyme in duodenum
inhibits gastric secretions
dilation of intestinal capillaries
Intestinal phase: cholecystokinin (CCK) (4 things)
release due to fatty acids in chyme in duodenum
stimulates bile secretions
inhibits gastric secretions
increases pancreatic juice (enzyme type)
When food enters stomach what happens to rugae
rugae flatten out. increase volume of stomach
Mixing waves in stomach
churning ~every 20 sec
80% of stomach movement
peristaltic contractions in stomach
more powerful than mixing waves
less frequent (20% of movement)
each squirt ~3mL of stomach content
stomach emptying relies on..
distention
greater distention = faster emptying
stomach distention does what (3 things)
activates stretch/mechano receptors
opens pyloric sphincter
fatty acids (hypertonic) low ph in duodenum inhibit gastric emptying
(detected by chemoreceptor)
time food sits in stomach
4 hours
high fat meal time in stomach
6 hours
time in stomach of moleules
CHO < protein < fats
liquids pass stomach in... (how long)
1.5-2 hours
when stomach emptying is too fast
efficiency of digestion and absorption is decreased
when stomach emptying too slow
can damage stomach wall
highly acidic content
increase in stomach motility...
increases emptying
-->local CNS reflexes activated = increase in gastrin
stomach emptying
increase stomach motility
how does the body inhibit gastric motility
hormonal and neural mechanisms
decreases stomach emptying
another word for vomiting
emesis
vomiting triggered by
extreme stretching of stomach
irritants (bacterial toxins, spicy foods, excessive alcohol, drugs)
medulla is trigger (emetic center in brain)
emetic center in the brain (causes vomiting)
medulla
signs of vomiting
increase in abdominal pressure
esophageal sphincter relax
soft palate rises (uvula covers nasal passage)
person is: pale, sweating, nauseated, SALIVATING
Small intestine
location of greatest digestion (chemical digestion and absorption)
SI secretions
mucus, electrolytes (na+), h2o
goblet cells secrete
mucus (stimulated by tactile and chem stimuli)
duodenal cells
secrete mucus to protect from acidic chyme
activated by vagal nerve
-->vagal nerve also stimulates secretin and stim goblet cels
most digestive enzymes come from...
pancreas
pancreatic juice types (2)
aqueous and enzymatic
aqueous pancreatic juice cont.
bicarbonate ions (increases pH)
na+ and k+ ions
water
enzymatic pancreatic juice contains (7 things)
trypsinogen -> trypsin
chymotrypsinogen -> chymotrypsin
procarboxypeptidase -> carboxypeptidase
pancreatic amylase
pancreatic lipase
deoxynuclease
riboxynuclease
what controls pancreatic stim
hormones and neural stimuli
Secretin in pancreas
stimulated by acid (chyme in duodenum)
results in stim of bicarbonate ions
CCK in pancreas
stim by fatty acids and amino acids
results in bile and enzymatic pancreatic juice
parasym response (vagal nerve) in pancreas
stim pancreatic juice
sympathetic response in pancreas
inhibits pancreatic juice
enzymes in intestine bound to...
microvilli
Pancreas: Disaccharidases: dextrinase and glucoamylase
degrade polysaccharides larger than 3 monomers
Pancreas: Disaccharidases: lactase, maltase, sucrase
degrade lactose, maltose, and sucrose
pancreas: peptidases: aminopeptidase and carboxypeptidase
break aas from ends of peptide
pancreas: peptidases: dipeptidase
only breaks dipeptide
pancreas: nucleases
break dna and rna
absorption of monosaccharides in SI
by secondary active transport (with na+)
absorption of aas in SI
nonpolar- diffusion
polar/charged- secondary active transport
lipids form _______ in lymph
chylomicron
chylomicron forms what in blood
LDLs HDLs
Chylomicron made up of (4 things)
phospholipid
triglyceride
cholesterol
protein
iliocecal sphincter
usu. closed
relaxes due to peristaltic contractions
each day ___ of water goes into digestive tract and ___ is absorbed
back into SI
9L
8-8.5L
Bile contains:
bile salts
cholesterol
fats
fat soluble hormones
lecithin
pigmented (green/yellow)
Liver function
produces bile (600mL - 1L)
bile contains digestive enzymes
bile does what:
dilutes
neutralizes
emulsify fats