The
Circulatory
System
•Blood
•Heart
•blood vessels
IN:
• What are four good reasons that blood
must be carried to all cells of the body?
• Why doesn’t a unicellular organism need
blood?
Function of the circulatory system:
• CIRCULATE blood throughout the
body
• Transport nutrients to cells
• Transport wastes away from cells
• Fight disease
• Maintain body temperature
Three kinds of blood vessels:
• Arteries
– represented by red
– Carry blood AWAY from the
heart
• Veins
– Represented by blue
– Carry blood back to heart
• Capillaries
– Microscopic vessels
that join arteries and
veins
• The artery has
thick muscular
walls so it can
Pulsate
• The vein has
valves inside to
keep blood flowing
toward the heart
against gravity
• Capillaries are only
one cell thick.
• This allows
molecules to pass
out of the blood to
surrounding cells
by diffusion while
other molecules
pass into the blood
What is passing out of the red blood cell at X?
What may be passing into the blood at Y?
What is passing out of the blood’s plasma at Z?
How does the circulatory system
regulate body temperature and
maintain homeostasis?
The Heart is a pump
• It’s made of cardiac
muscle tissue with
connective tissue
and fat tissue on the
outside
• It has four chambers
• Blood enters form the
vena cava, the largest
vein
• Blood leaves through
the aorta, the largest
artery
The heart has four chambers,
(chambers are spaces)
• Two atria- smaller
chambers at the top
(atrium singular)
– They receive blood from
veins, pump it to ventricles
• Two ventricles- larger
stronger chambers
below
– they pump blood out of
heart
• Valves (one way doors)
separate the chambers to
keep blood flowing the
right direction
Why is it essential for the mammal
heart to have four chambers?
(hint- mammals are very active)
Frog heart – 3 chambers
human heart – 4 chambers
Right side of the heart
• The atrium receives
deoxygenated (oxygen is
used up) blood from the
body through large veins
called the vena cava
(superior and inferior)
• The blood is pumped to
the right ventricle, then to
the lungs via the
pulmonary artery.
• What happens to blood in
the lungs?
Right
left
(the heart is facing you)
Left side of the heart
• Oxygenated blood
returns to the left
atrium from the
lungs
• It’s pumped through
a valve to the left
ventricle, then to the
body via the aorta,
or largest artery
Coronary circulation
• The heart is a hardworking muscle
• It needs a lot of
oxygen and nutrients
• this is supplied by
the coronary
arteries, and wastes
are removed by the
coronary veins
OUT:
• Draw red arrows (oxygenated) and blue
arrows (deoxygenated) on your heart
diagram to show how blood circulates
through the heart.