Transcript Digestive System

Brainstorm: Why do we have to eat in order to stay alive?
P.S. Helpful textbook pages include 446-450 (FYI)
It all starts in your mouth!
 Teeth grind up your food
into smaller pieces that are
easier to digest.
 Bonus: What simple
machine are your teeth?
(this is going way back to
Unit 1 in 6th grade)
 Different kinds of teeth
have different jobs.



Molars grind food down
Canines tear food
Incisors grab food
 Saliva starts to break food
down as you chew.
 Contains enzymes (what
are these again?)
 Comes from salivary glands
canine
incisor
molar
Food is delicious…but why?
 Taste buds (which have
touched on briefly) are tiny
modified hairs on your
tongue that tell our bodies
what something tastes like.
 Smell helps to enhance
taste, why do you think this
is?
 Different parts of your
tongue taste differently
 This is a general overview,
everyone is slightly different
and has some overlap of
sections
Onward to the Esophagus!
 Now that you have thoroughly
chewed your food you swallow
your bolus (chunk of chewed
food)
 Bolus enters the esophagus
 Muscular tube (~25 cm long)
 Secretes mucus to keep food
moist and moving (don’t you
just LOVE mucus?)
 Pushed down by smooth
muscle

Process called peristalsis
 So why doesn’t food go down
our windpipe when we
swallow?
 Bonus: What is our windpipe
called?
 Bonus: What body system is it
involved in?
 Fun Fact Question: What
organ do the digestive system
and respiratory system share?
And now for the Stomach!
 A stretchy, expandable,
muscular bag that can fold on
itself when “empty”
 Houses digestive enzymes (like
pepsin) and HCl (hydrochloric
acid) that help break food
down even further
 Four things happen when food
is heading to/has reached the
stomach:
 1) Your stomach releases
mucus (seriously this stuff is
everywhere) to coat itself and
protect its lining from acid
 2) Mechanical digestion mixes
food by peristalsis
 3) Chemical digestion breaks
food down with acids and
enzymes
 4) Food becomes chyme, a
“thin, watery liquid”
Small intestine yay!
 Measures 4-7 m in length
 Chyme enters the beginning of
your small intestine
(duodenum) where most
digestion takes place
 Bile (greenish liquid) is added
by the liver and digestive
solutions are added by the
pancreas as well
 Your pancreas also makes
insulin (a hormone that allows
sugar to enter your cells)
 Bonus: Why is sugar important
to your cells?
 Absorbs food through folds and
finger-like structures called villi
(increase surface area over
which nutrients are absorbed)
And last, but not least the Large
Intestine!
 Any undigested
chyme enters
large intestine,
which absorbs
water
 It becomes more
solid and is
pushed toward
the end of the
large intestine
(rectum) and out
of the anus as
feces
On a side (but important) note, eat
your yogurt!
 Your digestive tract contains
millions of symbiotic bacteria
that help aid in your digestion of
food.
 Bonus: What does symbiotic
mean?
 You need these bacteria to help
break down and absorb vitamins
 Bonus: What other part of your
body is important for this?
 Some of these bacteria live there
all the time, while others are
found in the food you eat (yogurt
is one of those foods).
So…put your notes away, let’s see
what we remember.
 Turn to a neighbor and see if
the two of you can accurately  And one last time for
and adequately describe the
good
process a sandwich goes
measure…MUCUS!!!!!!
through to digest in your
body.
 You have 3 minutes!