The Structure
of The Heart
The Heart
• Muscular pump, about the size of a clenched
fist
– Made up of a special muscle called
Myocardium
• This can contract continuously without getting
tired
• Main purpose is to drive blood through the
arteries
– This delivers blood to the working muscles and
other tissues.
Task…
Find a picture of a blank heart (that is suitable to annotate) and
upload it to a blank document.
- Then do some light background research on the different labels of
the heart including…
- Structure of the cardiovascular systemAtria
Ventricles
Bicuspid valve and tricuspid valve
Aortic valve and pulmonary valve
Aorta and vena cava – superior and inferior
Pulmonary vein and pulmonary artery
:
The Heart continued
• The Heart sits in a twin
layered sac known as
the Pericardium
– Filled with pericardial
fluid
• Prevents friction as
your heart beats.
The Heart continued
• The heart wall has 3 layers
–
(Outer)
(middle layer and most of the heart wall)
–
(The inner layer)
 Atria
 Upper chambers of the heart
 Receive blood.
 Right Atrium – receives deoxygenated blood from the body (Via
the Vena Cava)
 Left Atrium – receives oxygenated blood from the lungs (Via the
pulmonary Vein)
• Ventricles
– Lower chambers of the heart
– They have thicker walls and are
stronger
– Job is to pump the blood
– Right Ventricle pumps blood to the
lungs (pulmonary circulation)
– Left ventricle pumps blood to the
body (systemic circulation)
Valves
• Tricuspid Valve
• Bicuspid Valve
– Also known as the mitral valve
• Aortic Valve
• Pulmonary Valve
– All valves make sure that the blood
flows in one direction, and there is no
back flow
• Chordae Tendineae
– Cord like tendons that connect to the
tricuspid and bicuspid valves
• Ensure the valves stay the right way
round and keep the blood flowing in
the same direction.
Aorta and Vena Cava
• The largest vein is the
Vena Cava
– Carries blood
directly into the heart
from the body
– Superior vena cava
– brings blood from
the upper body
– Inferior Vena Cava
– Brings blood from
the lower body.
• The largest
Artery is the
Aorta
– Carries
oxygenated
blood directly
out of the heart
to the body
tissues
Pulmonary Circulation
• Pulmonary Artery
– Carries
deoxygenated
blood from the heart
to the lungs.
• It is the only artery
that carries
deoxygenated
blood
• Pulmonary Vein
– Carries
oxygenated blood
from the lungs to
the heart
• It is the only
vein that carries
oxygenated
blood.
The Heart = Double pump
• To describe the flow of blood
around the heart and the body,
you will need to mention that
the heart is made up of two
pumps
– Pulmonary circulation
• Pumps blood to and from the
lungs
– Systemic circulation
• Pumps blood around the body
Passage of blood flow
 Blood flows into and out of the
heart and around the body in
one direction.
 The heart is split into two
distinct pumps by the Septum.
 This makes sure that the
oxygenated and deoxygenated
blood don’t mix.
 When describing the passage
of blood flow around the heart,
it is best to use a diagram and
start on the right side of the
heart.
The
side of the heart
• Blood enters the heart (when it is relaxed) via the vena cavae,
• It goes into the right atrium
• The right atrium contracts and the blood goes through the tricuspid
valve and into the right ventricle
 The right ventricle contracts and the blood is
pushed out of the heart through the semi lunar
or pulmonary valve and into the pulmonary
artery
 The pulmonary artery carries the blood to the
lungs
 The heart relaxes and the valves close to stop
back flow of the blood
 In the lungs, the blood becomes oxygenated,
and begins it’s journey back to the heart.
The
side of the heart
• The heart is relaxed, and this
allows blood to enter the left
side of the heart from the
pulmonary vein
• It enters the left atrium
• The left atrium contracts and
pushes blood through the
bicuspid valve and into the
left ventricle
•
•
The left ventricle has a very strong muscular wall and contracts very strongly. This
closes the bicuspid valve to prevent backflow, and pushes the blood through the
aortic valve and into the aorta. This is the largest artery and splits taking the blood
to different areas of the body
The heart contracts and the aortic valve closes, preventing back flow of the blood.
Terminology
• Heart rate (H.R.)
– The amount of times the heart beats in a minute.
• Usually measured in beats per minute (b.p.m.)
• Stroke Volume (S.V.)
– The amount of blood leaving the left ventricle in one
beat.
• Normally measure in mililitres
• Cardiac Output
– The amount of blood leaving the heart in one minute
• Normally measured in litres/minute
• Cardiac Output = Stroke Volume x Heart Rate
Task…
 Finish off annotating and labelling the various parts of
the heart: