Transcript Lecture Chpt. 41 Digestion

Quick question: Whose genes matter most to you? Your
mom's? Your dad's? Or genes inside the trillions of bacteria
living in your intestine, your mouth, your nasal passages and
a lot of places we'd rather not mention?
The answer: Obviously, your parents' genes matter, but it turns
out we humans have two sets of genes in us: the ones we
inherited from our human ancestors and the ones that walk in
through our mouths starting when we're just hours old.
"We're all sterile until we're born," says Glenn Gibson, a
microbiologist at the University of Reading in Britain. "We
haven't got anything in us right up until the time we come into
this big, bad, dirty world."
NPR All Things Considered: 11/4/08
http://www.npr.org/blogs/kr
ulwich/2011/06/10/137084
528/gut-bacteria-knowsecrets-about-your-future
Chpt.
41
• The tube is organized into specialized regions that
carry out digestion, & nutrient absorption.
Chewing: mechanically disassembles the food - smaller particles =
advantage more surface area
salivary
amylas
e
Starch & Glycogen
small polysaccharides &
maltose (disaccharide)
->
bolus
mucus helps bolus slide
bolus
mucus helps bolus slide
bolus
Peristalsis
bolus
cardiac orifice
pyloric sphincter
stomach
bolus
HCl
pH of 2 -> breaks protein bonds (peptide
& converts pepsinogen (inactive, precursor
enzyme) into pepsin (digestive enzyme of the stomach)
bonds)
stomach
bolus
Pepsin
proteins -> short polypeptides & amino
Form Follows Function
pepsin converts more pepsinogen… + feedback
HCl converts pepsinogen to pepsin
Chief cells secrete pepsinogen
GASTRIN –
hormone,
stimulates HCl by
the pariatel cells
chyme
3 - 4 hrs.
Your stomach can hold 2-4 liters
chyme
relaxes
small intestine
chyme
diffuses nutrients into blood / much enzyme activity f
hydrolysis of molecules
small intestine
buffer
released
chyme
offsets acidic chyme from stomach into
small intestine
Form Follows Function,
brush border
Same surface area as a tennis court
Therfore, more area for absorption of
nutrients to blood stream
Form Follows Function
Form Follows Function
small intestine
pancreatic
amylase
chyme
small polysaccharides-> maltose
& other disaccharides
small intestine
pancreati
c lipase
chyme
fat droplets ->glycerol, fatty acids
small intestine
nuclease
chyme
DNA/RNA -> nucleotides
small intestine
trypsin
chyme
polypeptides -> -> dipeptide
small intestine
maltase
chyme
maltose -> glucose
small intestine
lactase
chyme
lactose -> glucose
small intestine
sucrase
chyme
sucrose -> glucose
liver
bile
chyme
fat globules -> -> fat droplets
Liver produces BILE
stored in
the gall-bladder - emulsifies fat
stored in gall bladder
bile
liver
detoxifies
alcohol
chyme
Large Intestine (colon)
1.5 meters long!!
large intestine
absorbs water,
unabsorbed
chyme, &
undigested
material not
absorbed in the
sm. intestine
undigested
chyme
[ unabsorbed
Too much absorbed
anus
expulsio
n of
feces
undigested
chyme
Feces is composed of approximately 75%
water and 25% solids. One-third of the
solids is intestinal bacteria, 2/3’s is undigested
mouth
glottis
entrance
esophagus
liver
fat body
small
intestine
large
intestine
gall
blad
der
Unable to
see:
pancreas,
stomach
anus