Download The Digestive and Excretory Systems

The Digestive and Excretory
Systems
EQ: HOW DO ORGAN SYSTEMS WORK
TOGETHER TO ENABLE AN ORGANISM TO
MAINTAIN HOMEOSTASIS?
Functions of the Digestive and Excretory
Systems
Digestive System
Excretory System
 Getting food into your
 Getting the materials
body
 Digesting the food
 Absorbing the
nutrients you need
 Eliminating solid waste
you don’t need out of
your body.
 Fluids: Liquids, gases
The Digestive System
 You feel hungry because
your brain receives signals
that your cells need energy.
 But eating is only the
beginning of this story.
 Your body must change a
meal into substances you
can use.
 Your digestive system is a
group of organs that work
together to digest food so
that it can be used by the
body.
Two Types of Digestion
Mechanical
Chemical
 The breaking, crushing,
 Large molecules of
mashing and
pulverizing of the food
food are broken down
into the nutrients that
the body needs for
normal growth,
maintenance and
repair.
Organs of the Digestive System
 Teeth
 Esophagus
 Stomach
 Pancreas
 Small Intestine
 Liver
 Gallbladder
 Large Intestine
Teeth
 Teeth are very important
organs for mechanical
digestion,
 They break and grind food
into smaller pieces so they
can be swallowed more
easily.
 As you chew, saliva
moistens your food to make
it slipperier.
 Saliva also contains
enzymes that begins the
chemical digestive process.
Esophagus
 Once your food is reduced
to a soft mush, the tongue
pushes it down the throat,
which leads to a long,
straight tube called the
esophagus.
 The esophagus squeezes
the food down to the
stomach with muscle
contractions.
 These contractions are
called peristalsis.
Stomach
 Peristalsis forces your food into
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your stomach.
The stomach is a muscular,
saclike organ.
The stomach continues to
mechanically digest your food by
squeezing it with muscular
contractions.
While this squeezing takes place,
enzymes and acids are being
produced, which helps with the
chemical break down of your
food.
After a few hours of this
mechanical and chemical
digestion, your food is reduced
to a soupy mixture called chyme.
The Pancreas
 Most chemical digestion takes
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place after your food leaves your
stomach.
When the chyme leaves the
stomach, the chyme is very acidic.
The chyme never actually enters
your pancreas, which is ovalshaped and between the stomach
in small intestine
Instead, the pancreas produces
fluid (pancreatic fluid) that
contains enzymes that further
breaks down the chyme and
neutralizes the acids in the chyme.
These fluids flow into the small
intestine.
The pancreas also helps produce
hormones (endocrine system) to
help regulate blood sugar.
Small Intestine
 The small intestine is a
muscular tube that is about
2.5 cm in diameter, and
about 6 m in length.
 Inside the small intestine,
there are finger-like
projections called villi.
 The villi are covered with
tiny, nutrient-absorbing
cells.
 Once the nutrients are
absorbed, they enter the
blood stream to deliver the
nutrients to your body.
Liver
 The liver is a large, reddish
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brown organ that helps
with digestion.
It is about the size of a
football.
The liver helps with
digestion in the following
ways:
Makes bile to break up fat
Stores nutrients to be
released later
Breaks down toxins such as
alcohol.
Gallbladder
 Although bile is made by
the liver, bile is
temporarily stored in the
gallbladder.
 Bile is squeezed from the
gallbladder into the small
intestine, where the bile
breaks large fat droplets
into smaller droplets.
Large Intestine –The End of the Line
 Material that cannot be absorbed
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into the blood is pushed into the
large intestine.
The large intestine stores,
compacts and eliminates
indigestible material from the
body.
It is about 1.5 meters long and 7.5
cm in diameter.
Undigested material enters the
large intestine as a soupy
mixture.
The large intestine absorbs most
of the water and changes the
liquid into a semisolid waste
called feces.
Rectum
 The rectum is the last
part of the large
intestine.
 It stores the feces until
they can be expelled.
 It generally takes 24
hours from the time your
food enters your mouth
until it is expelled from
your body.
The Excretory System
 The excretory system is very important to your body
and has only a few parts.
 In a similar way to removing solid waste from your
body, you must also get rid of fluids.
 Excretion is the process of removing waste products
from your body.
Three of your body systems have a role in
excretion
 Your integumentary
system releases water a
waste by way of sweat.
 Your respiratory system
releases carbon dioxide
and water when you
exhale.
 Your urinary system
contains the organs that
remove waste products
from your blood.
Organs of the Urinary System
 Kidneys – a filtering organ
that constantly clean the
blood.
 Ureter – tubes leading
from the kidneys to the
urinary bladder.
 Urinary bladder --- a sac
which holds the urine until
it is expelled from your
body
 Urethra – a tube through
which the urine leaves your
body