Download blood vessels.

Lesson 12
What is the circulatory system?
Can you imagine being a
messenger that makes trillions of
stops in just 30 seconds????
Your blood does!
Blood is an important body
messenger. It is on the move
day and night.
In just 30 seconds, your blood
moves or circulates through
your whole body. It reaches out
to all of your trillions of cells.
Blood transports (carries) to the
cells all the things it needs.
What do your cells need?
Cells need things like:
oxygen
digested foods
The cells absorb or take in
these materials.
The blood is also your body’s
trash collectors.
What type of things are made in
the cells that need to be taken
out with the trash?
heat
carbon dioxide
extra water
The blood picks up these waste
materials from the cells and
takes them to places that get
them out of the body. (we will
talk about that later in the year)
Blood is pumped throughout the
body by the heart. It flows
through a closed system of
tubes, called blood vessels.
Your body has three types of
blood vessels.
Arteries:
-carry blood away from the heart
-carry the materials the cells
need
-except the arteries going to
the lungs carry blood rich in
oxygen and nutrients
Veins:
-carry blood from the body
back to the heart
-except the veins coming from
the lungs, veins carry blood with
dissolved waste products
Capillaries:
-connect arteries and veins
-are microscopic
-most of the blood vessels in
your body are capillaries
The heart, blood vessels, and
blood make up your circulatory
system.
Circulation, or transport, is a
vital function. Life can not go on
without it.