Muscular double pump. The right
side pumps deoxygenated blood.
The left side pumps oxygenated
blood.
Valves in the heart
prevent blood
flowing the wrong
way
Atrioventricular valves
link the atria and the
ventricles
The semi-lunar
valves link the
ventricles to the
pulmonary artery and
aorta.
Thickness of the chamber walls
Atria: the muscle is very thin. This
is because these chambers do not
need to create much pressure.
Their function is to push the blood
into the ventricles
Right ventricle: They are
thicker than the atria walls.
Enables the ventricle to push
blood out of the heart. It is
thinner than the left ventricle as
it only pumps deoxygenated
blood to the lungs which are
next to the heart. The lungs
have thin capilaries and could
easily burst if the pressure is
very high
Left ventricle: The blood pumped
out of the left ventricle is pumped
through the aorta and needs
sufficient pressure to overcome
the systemic circulation
Cardiac cycle
1. Diastole: Ventricles and atria
relax, internal volume increases and
blood flows into the heart. Blood
flows into the atria and through the
atrioventricular valves.
2.Atrial systole: Atria contract and
ventricles relax. The contraction helps
push the blood into the ventricles and
ensures they are full of blood. Blood
fills the atrioventricular valves and
they snap shut
3. Ventricular systole: Ventricles contract
and atria relax. Contraction at the apex of
the heart and the blood is pushed
upwards. Semilunar valves open and
blood is pushed out of the heart
Cardiac muscle
Sinoatrial node(SAN): Is in
the right atrium and is a
pacemaker. Sets the rhythm
of the heartbeat. Sends
excitation waves to the artrial
walls.
Both atria contract
Collagen prevents
the waves from
being passed
directly from the
atria to the
ventricles
The waves are
transferred from the
SAN to the
atrioventricular
node(AVN)
The AVN is in the septum of
the heart. There is a delay to
make sure all the blood is in
the ventricles before it
contracts
The excitation waves travel down
the Purkyne tissue and causes the
ventricular walls to contract from the base
ECG
P wave: Excitation of the atria.
QRS wave: excitation of the
ventricles. T wave: shows diastole