The Circulatory System
The heart, blood vessels and
blood make up the circulatory
system.
One-way circulation
The English scientist
William Harvey
showed that blood
circulates one-way
through blood
vessels.
Arteries carry blood
away from the heart
Veins carry blood to the
heart
The heart is a
muscular organ
that beats
involuntarily.
It is made up of
cardiac muscle
that needs a large
supply of ATP.
(energy)
Chambers of the Heart
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The heart has 4
chambers.
The atria collect
blood coming into
the heart
The ventricles
pump blood out of
the heart
Oxygen Poor Blood: Enters
the right side of the heart
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
Blood from the
body enters the
heart through the
superior and
inferior vena cava.
The blood empties
into the right
atrium and is then
put into the rt.
ventricle.
Pulmonary Arteries
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The deoxygenated
blood is pumped out
of the heart through
the pulmonary
arteries (the only
arteries that carry
deoxygenated blood)
These arteries carry
blood to the lungs to
pick up oxygen and
drop off carbon
dioxide.
Pulmonary Veins

Oxygen-rich blood
leaves the lungs
and enters the left
atrium of the heart
through the
pulmonary veins.
(the only veins that
carry oxygen-rich
blood)
Oxygen Rich blood: From the lungs
through the left side of the heart
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Oxygenated blood
from the lungs enters
the heart
This blood passes
from the left atrium
into the left ventricle
Then out of the heart
through the aorta (the
largest artery)
Vessels
Arteries always carry blood away from the
heart.
Veins always visit the heart.
Capillaries are small and connect arterioles
to venules.
4 valves within the heart
Within the heart,
structures called
valves
Valves keep blood from
flowing backwards
*Blood circulation
through the heart
animation:
https://www.youtube.com
/watch?v=oHMmtqKgs5
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Blood Pressure
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Blood pressure is the pressure exerted by blood
on the blood vessel's walls.
Hypertension is excessively high blood pressure.
Functions of Blood
Regulate body temperature
Regulate pH
Regulate ions in solution
Protect body from invaders
Restrict the loss of fluid
Blood
Several important blood cells include
 red blood cells,
 white blood cells, and
 platelets
Red Blood Cells = erythrocytes

most numerous type of blood cell

Erythrocytes contain the protein hemoglobin

Hemoglobin contains iron and helps to carry
oxygen around the body
Leukocytes
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White blood cells =
leukocytes
Produced in the bone
marrow like red blood
cells
Leukocytes are larger
than red blood cells
Leukocytes protect the
body against foreign
substances like viruses
and bacteria
Platelets

Platelets:
 Tiny fragments of cells
and plasma proteins
 Platelets help to clot the
blood.
 Platelets come into
contact with the edges of
a broken blood vessel,
their surfaces become
very sticky and cluster of
platelets develop around
the wound
 Clotting factors start a
series of reactions


How does blood
clot?
https://www.yout
ube.com/watch?v
=--bZUeb83uU
Lymphatic system
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The lymphatic system contains small
glands and vessels that collect fluid lost
by the blood
Returns it to the circulatory system
Lymph nodes act as fluid filters and can
produce special white blood cells