bio digestion system

1. Location Overview Mechanical Digestion Chemical Digestion
Mouth -food is chewed and
grounded
-saliva glands secrete
saliva
-food forms bolus
easier to swallow (bc
soft and moist)
-food is
broken/ground/chewe
d into smaller pieces
-increase in surface
area for chemical
digestion
-saliva contains
salivary amylase
And begins starch
digestion and glucose
-pH becomes neutral
Esophagus -wave like
contractions push
bolus to the stomach
-main function:
transport food from
mouth to stomach for
digestion
-esophageal
sphincter keeps food
from re-entering
esophagus
-multiple peristalsis at
one time
-sometimes a bolus
of food can be cut
into smaller pieces by
wave-like
contractions,
increasing the SAs
and making it easier
for stomach to digest
-chemical breakdown
continues from mouth
-amylase not acidic
enough to cause a
burning sensation
Stomach -food enters through
pyloric sphincter
-muscular J shaped
organ where food is
temporarily stored
-churns food and
breaks it down
-stomach expands
after a meal
-lined with gastric
glands (protected by
mucus)
-3 layers of muscles
-nerve initiates
stomach contractions
that release partially
digested food into
smaller intestine
-muscle fibres churn
the food producing a
thick liquid called
chyme
-- further increases
SA of food
-gastric glands
secretes gastric
juices
(enzymes, H20 and
protein)
-pepsin (enzyme that
digests protein)
Small intestine -long winding tubes
connected to
stomach
-food digested and
absorbed by
bloodstream
-3 parts:
Duodenum ( breaks
-digesting food is
pushed through
waves of muscular
contractions and
relaxations called
peristalsis
-
-pancreatic amylase
breaks down starch if
not done already
-digests enzymes
from pancreas and
breaks down
macromolecules
-carbohydrates and

2. down food)
Jejunum
Ileum
Last 2 both absorb
nutrients into
bloodstream
proteins are
absorbed
- hormone secretin
releases bicarbonate,
neutralizes stomach
acid
Large Intestine -consists of cecum,
rectum, anal canal
and colon
-absorbs water back
into blood as well as
salts and vitamins
-bacteria in L.I
produces vitamins
that the body absorbs
-volume of
indigestible food is
reduced to ⅔
-billions of anaerobic
bacteria in colon
break down
indigestible material
further
-wave like
contractions push the
semi-digestible food
down to digestive
track
-anaerobic bacteria
further breaks down
food in colon
Rectum and Anus -temporary storage
for feces waste
material
-a ring of muscle that
keeps everything in
rectum until it is time
-more stretched
rectum wall= more
you feel need to poop
None none
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