innit 6 human :
physiology
the structure the wall of the small intestine allows it to digestion & absorb food
of move
,
the human
complex tube from the mouth to the attached to it secreting enzymes &
hormones
°
a
organs
arms →
of the digestive tract / alimentary canal
forming the tube
°
organs organs
-
secreting chemicals
°
accessory organs organs
-
steps the mouth
mechanically mixed with (moistens helps swallow)
o
. o
in
, food is saliva mixture
,
°
saliva contains amylase digestion of starches
→
°
bolus (food mixture) enters oesophagus (gullet) →
moves to the stomach by peristalsis
°
peristalsis -
a contraction & relaxation
wave
of longitudinal & circular muscles (opposite) of
the alimentary canal contents→
forced along
°
longitudinal contract to widen the lumen circular contracts to constrict lumen
the stomach
food churned with acid chyme food & acid mixture
°
in is → -
,
kills btacteria & starts digestion of proteins
small intestine duodenum
first section
.
→
→ neutralization
of stomach acids so
enzymes can function
↳ ideal neutral to alkaline
pH
,°
the lipids ; further digest carbohydrates & proteins
digest fats &
enzymes
the ileum the last section
of small intestine (the digested food absorbed from it)
°
is
-
where most absorption takes place
°
large intestine digested juices & undigested material enter
-
H2O vitamins (Kd B) made by bacteria
-
,
reabsorbed are
↳
can
ferment undigested polysaccharides (E production)
faeces formed & stored the rectum before egestion
-
in
① The
pancreas
- secretes amylase lipase & protease (aid digestion)
,
into
the small intestine
② Liver secretes bile to
emulsify lipids (breaks up large globules)
③ The bladder shoes bite
gall
°
in the small intestine → a muscular tube (about G 7
-
m ) between the stomach & large intestine
3
parts duodenum , and ileum
°
jejenum
:
with villi (increase SA
surface covered
by 30 60
fold) increased absorption
°
inner - →
: o
serosa : outermost layer of connective tissue in contact with body cavities
°
longitudinal & circular muscles :
peristalsis
°
submucosa :
connective tissue
supporting the mucosa
,
contains large veins & arteries
which
give
rise
capillary bed of
to mucosa
innermost layer
forms the soft lining of tube comprised of epithelium
°
:
connective
mucosa
,
tissue & ( ) smooth muscle villi
small intestine
where broken down to taken by the blood
food is absorbed
by villi the
lymph
°
→ →
monomers
up
or
units
Digestion :
large food molecules smaller
the smaller units monomers (easily absorbed)
the (for breaking down) secrete into the lumen (central
space)
the intestine
pancreas &
wall the
of produce
°
enzymes
°
acinar cells secrete
digestive enzymes
duct cells
transport & secrete sodium
hydrogen carbonate
enzymes
through pancreatic duct
pancreatic juice neutralise , stomach acid
lumen small intestine
into the duodenum of
, islets
of Langerhans produce the hormones insulin & glucagon
*
Digestive enzymes amylase starch : :
→ maltose
endopeptidase /trypsin proteins smaller polypeptides
: → have
optimum
" k a)
lipases & phospholipase lipids / phospholipids glycerol fatty acids ( phosphate)
P
→
:
→
,
still too large for vili to take
despite most molecules
°
in
enzymes
are
,
wall of the has immobilised the intestinal epithelial cells
si .
glands produce enzymes
in
Enzymes :
nucleases :
break down DNA & RNA
maltase :
maltose →
glucose
lactase : lactose →
galactose & glucose
exo
peptidases :
remove
single AA
from the end
of small
poly pep .
two
di
peptidases dipeptide AA
:
→
these with
happen by peristalsis helps food & enzymes
°
mixing
→
processes
* cellulose remains
undigested (humans don't
produce cellulose)
intestinal villi
°
food absorption takes place mainly in the small intestine ,
across the epithelium
large SA needed to
enough transport proteins absorb all necessary nutrients
°
a is ensure
by villi location absorption
of
increased
of all digested monomers
absorption taking of digested food substances minerals & vitamins from the lumen of small intestine into the blood
°
-
in
,
producge
mucus
takes
f.
where absorption place
connective
=
tissue
absorbed
carry
nutrients away
intestine
from
microvilli membrane into the lumen
projections of each epithelial cell 's plasma
°
-
-
further surface
increase area
physiology
the structure the wall of the small intestine allows it to digestion & absorb food
of move
,
the human
complex tube from the mouth to the attached to it secreting enzymes &
hormones
°
a
organs
arms →
of the digestive tract / alimentary canal
forming the tube
°
organs organs
-
secreting chemicals
°
accessory organs organs
-
steps the mouth
mechanically mixed with (moistens helps swallow)
o
. o
in
, food is saliva mixture
,
°
saliva contains amylase digestion of starches
→
°
bolus (food mixture) enters oesophagus (gullet) →
moves to the stomach by peristalsis
°
peristalsis -
a contraction & relaxation
wave
of longitudinal & circular muscles (opposite) of
the alimentary canal contents→
forced along
°
longitudinal contract to widen the lumen circular contracts to constrict lumen
the stomach
food churned with acid chyme food & acid mixture
°
in is → -
,
kills btacteria & starts digestion of proteins
small intestine duodenum
first section
.
→
→ neutralization
of stomach acids so
enzymes can function
↳ ideal neutral to alkaline
pH
,°
the lipids ; further digest carbohydrates & proteins
digest fats &
enzymes
the ileum the last section
of small intestine (the digested food absorbed from it)
°
is
-
where most absorption takes place
°
large intestine digested juices & undigested material enter
-
H2O vitamins (Kd B) made by bacteria
-
,
reabsorbed are
↳
can
ferment undigested polysaccharides (E production)
faeces formed & stored the rectum before egestion
-
in
① The
pancreas
- secretes amylase lipase & protease (aid digestion)
,
into
the small intestine
② Liver secretes bile to
emulsify lipids (breaks up large globules)
③ The bladder shoes bite
gall
°
in the small intestine → a muscular tube (about G 7
-
m ) between the stomach & large intestine
3
parts duodenum , and ileum
°
jejenum
:
with villi (increase SA
surface covered
by 30 60
fold) increased absorption
°
inner - →
: o
serosa : outermost layer of connective tissue in contact with body cavities
°
longitudinal & circular muscles :
peristalsis
°
submucosa :
connective tissue
supporting the mucosa
,
contains large veins & arteries
which
give
rise
capillary bed of
to mucosa
innermost layer
forms the soft lining of tube comprised of epithelium
°
:
connective
mucosa
,
tissue & ( ) smooth muscle villi
small intestine
where broken down to taken by the blood
food is absorbed
by villi the
lymph
°
→ →
monomers
up
or
units
Digestion :
large food molecules smaller
the smaller units monomers (easily absorbed)
the (for breaking down) secrete into the lumen (central
space)
the intestine
pancreas &
wall the
of produce
°
enzymes
°
acinar cells secrete
digestive enzymes
duct cells
transport & secrete sodium
hydrogen carbonate
enzymes
through pancreatic duct
pancreatic juice neutralise , stomach acid
lumen small intestine
into the duodenum of
, islets
of Langerhans produce the hormones insulin & glucagon
*
Digestive enzymes amylase starch : :
→ maltose
endopeptidase /trypsin proteins smaller polypeptides
: → have
optimum
" k a)
lipases & phospholipase lipids / phospholipids glycerol fatty acids ( phosphate)
P
→
:
→
,
still too large for vili to take
despite most molecules
°
in
enzymes
are
,
wall of the has immobilised the intestinal epithelial cells
si .
glands produce enzymes
in
Enzymes :
nucleases :
break down DNA & RNA
maltase :
maltose →
glucose
lactase : lactose →
galactose & glucose
exo
peptidases :
remove
single AA
from the end
of small
poly pep .
two
di
peptidases dipeptide AA
:
→
these with
happen by peristalsis helps food & enzymes
°
mixing
→
processes
* cellulose remains
undigested (humans don't
produce cellulose)
intestinal villi
°
food absorption takes place mainly in the small intestine ,
across the epithelium
large SA needed to
enough transport proteins absorb all necessary nutrients
°
a is ensure
by villi location absorption
of
increased
of all digested monomers
absorption taking of digested food substances minerals & vitamins from the lumen of small intestine into the blood
°
-
in
,
producge
mucus
takes
f.
where absorption place
connective
=
tissue
absorbed
carry
nutrients away
intestine
from
microvilli membrane into the lumen
projections of each epithelial cell 's plasma
°
-
-
further surface
increase area
