Download The Heart

The Heart
How it works
The Heart
Facts




The heart is the organ that supplies blood and oxygen to
all parts of the body and gets rid of waste as well
It is about the size of your clenched fist
It weighs 10.5 oz
The heart is surrounded by a fluid filled sac that helps to
anchor the organ in place and provides lubrication and
protection called the pericardium.
Superior Vena Cava
Large diameter
 Short vein
 Carries deoxygenated
blood from the upper
half of the body to
the right atrium

Inferior vena Cave
Large vein
 Carries deoxygenated blood
from the lower half of
the body to the right
atrium

Right Atrium
One of four chambers
in the human heart
 It receives deoxygenated blood
from the SVC and the
IVC
 Pumps the blood into
the right ventricle

Atrioventricular Valve - Tricuspid
On the right side
between the right
atrium and the right
ventricle
 Three leaflets that
open when the atrium
contracts to push the
blood into the
ventricle
 Prevents the backflow
of blood

Right Ventricle
The second of four
chambers for the
blood to enter
 Receives the
deoxygenated blood
and pumps it into the
pulmonary artery
through the
pulmonary trunk
 More muscular than
the atrium

Pumping
The right ventricle will contract when
there is the proper amount of blood and
pressure in the chamber
 The atrioventricular valve (tricuspid) will
close so the blood DOES NOT go back into
the right atrium
 The pulmonary valve will open when the
pressure from the contraction is increased.

Pulmonary Valve
Also called the
semilunar valve
 Lies between the
ventricle and the
pulmonary trunk then
arteries
 It disperses the
deoxygenated blood
into the pulmonary
arteries and prevents
backflow

Pulmonary Arteries
Arteries carry blood
away from the heart!
 Usually it is
oxygenated
 BUT These arteries
have deoxygenated
blood and it is
transferred to the
lungs

Pulmonary Veins
Large blood vessel
 Always carry blood to
the heart, usually
deoxygenated
 BUT these carry
oxygenated blood
from the lungs back
to the heart
 There are four
pulmonary veins

Left Atrium
Gathers the
oxygenated blood
from the pulmonary
veins
 When the right atrium
contracts, so does the
left

Mitral Valve
AKA: Atrioventricular valve
On the left side of the
heart
 Separates the blood in
the atrium from the blood
in the ventricle
 Has two leaflets
 The diagram shows a
malfunction where it
allows blood back into the
atrium – Prolapse
 Prevents the backflow of
blood

Left Ventricle
Very muscular 4th
chamber of the heart
 Must pump the
oxygenated blood to
all parts of the body
through the aorta

Pumping
The oxygenated blood is pumped from the lungs where the
oxygen is ‘picked up’ to the heart by the pulmonary veins.
 It then enters the left atrium and when there is sufficient
volume and pressure (greater than that in the left ventricle)
the atrium contracts which opens the mitral (atrioventricular)
valve. The blood rushes into the ventricle and when the
pressure and volume here are correct the muscular ventricle
will contract and the mitral valve closes and the aortic valve
opens.
 There is NO backflow of the blood in the heart
 The musculature of the left ventricle is greater than that of
the right. WHY?

Aortic Valve
Valve that is opened
when the left ventricle
contracts allowing the
oxygenated blood to
enter the aorta
 Normally has three
leaflets
 The blood in the
ventricle must have a
greater pressure than
that in the aorta

Aorta
The largest artery in the
human body
 Originates from the left
ventricle and extends down
into the abdomen
 It distributes oxygenated
blood to all parts of the
body
 The blood from the aorta
first passes into the
coronary arteries to supply
blood to the cardiac (heart)
muscle.

Cardiac Cycle
The sequence of events that occurs when
the heart beats
 Two phases:
Diastole – Ventricles are relaxed, lower
pressure
Systole – Ventricles contract, higher
pressure

Diastole





During this portion of the cycle, the ventricle is
relaxed
The atrioventricular valves are open
The pulmonary valve and the aortic valve are
closed
The ventricles fill with blood – right is
deoxygenated and the left is oxygenated
The atria contract filling the ventricles until the
pressure is greater than in the blood vessels
Systole
Ventricles have contracted
 The atrioventricular valves have closed
 The aortic and pulmonaric valves are
opened
 Blood rushes from the ventricles to the
aorta and pulmonary arteries

Fun Facts





The heart beat is strong enough to squirt blood
30 feet
The longer a boy’s ring finger is, the less likely
they are to suffer a heart attack
The human heart beats ~ 35 million times per
year
The heart pumps ~ 1 million barrels of blood in
a lifetime
Most heart attacks occur between 8 – 9 a.m.
Fun Facts





The blue whale has the largest heart – it weighs
one ton (approximately)
The hummingbird heart beat is 1000 times per
minute
Your entire blood volume goes through your
entire body once every minute
Humans have ~ 60, 000 miles of blood vessels
in their bodies
Pig and baboon hearts have been transplanted
into humans
Blood direction
DEOXYGENATED
Superior vena cava and inferior vena cava  Right Atrium
 through the tricuspid valve  Right Ventricle 
through the aortic valve  the Pulmonary arteries  TO
THE LUNGS
OXYGENATED
Pulmonary veins  Left Atrium  through the mitral valve
 Left Ventricle  through the aortic valve  Aorta  to
every cell of the body  back to the vena cava!!
Full Circle!
Label your diagram
Quiz tomorrow!!!!