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Anatomy of the
Heart
By: Alisa Courville
Structures of the heart
 The wall of our heart is
called the Septum. It is up
to the Aorta, Superior vena
cava, Inferior vena cava,
our 4 chambers, our
pulmonary arteries and
pulmonary veins, and
valves in our heart to allow
oxygen exchange
throughout the body and
our lungs.
 Our superior vena cava
collects deoxygenated
blood from our upper
body and returns it back to
the heart.
 Our inferior vena cava
collects all spent blood
from the lower body and
returns it back to the
heart.
 The Left and Right Atrium
collect blood, while our Left
and Right Ventricles pump
blood to the rest of the
body. On the Right side of
your heart you have your
Tricuspid Vales and on the
Left side you have your
Mitral/Bicuspid Valve. These
valves both prevents black
flow of blood into our atria.
 The Aorta is a major blood
vessel that branches off to
pump blood to other major
arteries in the body.
 Our pulmonary veins and
arteries aid in the
pulmonary circuit where
our oxygen exchange takes
place.
The Cardiac Cycle
 Contractions in the heart are a two step
process:
Systole -contraction of the heart
Diastole - relaxation of the heart
*Each HB is it’s own cardiac cycle
When we listen to our Heart Beat the sound we
hear is usually a “lub-dub” kind of sound, this is
from the opening & closing of the valves:
1st: Atrioventricular 2nd semi-lunar
 Ventricles must have a stronger and longer
contraction of blood because blood must be
pumped throughout the body.
*The beat is controlled by a special type of tissue called “Nodal Tissue” which
has both muscular and nervous tissue features.
Intrinsic Heart Beats
There are 2 locations of nodal Tissue:
1) SA Node (Sinoatrial Node) also called the pace
maker and is found in the upper right atria, initiates
the heart beat and sends out an excitation HB
every 0.85 seconds. The impulse causes both atria
to contract
2) The AV Node ( Atrioventricular Node) which is
found at the bottom of the right atrium near the
septum, which contain purjinki fibers that are
found in the walls of the ventricles and septum.
* Purkinji Fibers stimulates both ventricles to contract from the
bottom upwards
Electrocardiograms
 Electrocardiograms register voltage changes across
the surface of the heart as it beats.
The letters PQRST are the standard labels used to
identify the parts of the EKG.
The P Curve records the simultaneous contractions of
the Atria as it drives the blood out into their ventricles.
The Q,R & S curve is the contraction of ventricles as
their driven out of the blood out into their respective
arteries
The T marks the recovery of the Ventricles which
prepares them for the next contraction
Autonomic Control of the Heart
Your heart Rate can be controlled not only by the
cardiac cycle but also by your nervous system
The Heart Rate control centre is located in the
Medulla Oblongata of the brain
The Vagus Nerve has two systems which effect your Heart
Rate:
1) Parasympathetic System: causes your Heart Rate to
slow down
2) Sympathetic System: causes your Heart Rate to increase
The SA Node is connected to your brain by the
“Vagus Nerve” which is connected and found in the
nervous system
Factors that will effect your heart rate, some including:
*Exercise
*Stress
*Alcohol/Drugs
*Diet
 Lack of Oxygen and Blood Pressure levels will signal which
system should come into play
Blood pressure:
The force of blood against blood vessel walls
How does blood pressure work?
- When ventricles contract, approximately 70 ml of blood is
released, this is why our Arteries need thick and elastic walls in
order to withstand the blood pressure
*Blood Pressure readings are not consistently the same
When reading or taking blood pressure there are two different readings: Systolic and
Diastolic
 Systolic Pressure: refers to the pressure when ventricles are contracting. This is the
highest BP reading.
 Diastolic Pressure: refers to is the pressure when the heart is at rest. This is the
lowest BP reading
* Pulse: As blood pumps through our Arteries, the arterial walls swell & then re-coils. The swelling
can be felt in any Artery that is close to the skin
Blood Pressure cont..
 Blood pressure is typically measured along your brachial artery which can be
found along the inner middle of your arm.
 A normal Blood Pressure reading is typically 120/80
120 being our systolic pressure & 80 being our diastolic pressure.
 Hypertension: High blood pressure ie. 140/90 or
125/90
Diet and lifestyle are often the main reasons of hypertension, examples are:
• Stress / working too hard
• Diet (high salt intake)
• Smoking
• Age, sex, and race
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Hypotension: Low blood pressure ie. 90/60
Cuts/amputated limbs
 Plaques: formed by fatty deposits from digested foods. Plaques line the arterial walls
Drugs
which create less surface area resulting in hypertension
Hormones additives
 Proper Kidney function can only be maintained if there is sufficient pressure for
filtration