HEART
• Define the function of the heart
• Identify the different layers of the heart and their function
• Identify the chambers of the heart
Location
• The heart is located in the
thoracic cavity
• Posterior to the sternum
• Superior to the diaphragm
SE
BA
• Between the lungs
• The tip of the heart is called
the ‘apex’ EX
AP
Image source – See slide 28
Anatomy
Image source – See slide 28
The heart has:
3 layers
• pericardium
• endocardium
• myocardium
4 chambers
• 2 atrium
• 2 ventricles
4 valves
• Mitral
• Aortic
• Tricuspid
• Pulmonary
Function
• The heart pumps oxygen and nutrient
rich blood to the organs, tissues and
cells of the body, and eliminates
waste products
Image source – See slide 28
Function
• Blood is carried from the heart
to the organs through arteries,
arterioles and capillaries
• Blood returns to the heart
through venules and veins
Image source – See slide 28
Layers of the Heart
Pericardium:
The heart is surrounded by a fibro serous
sac called the pericardium
The function of the pericardium is:
• To limit cardiac distension and
restrict excessive movement
• To protect and lubricate
The pericardium is composed of:
• Visceral
• pericardium
• Parietal pericardium
Pericardial cavity
Image source – See slide 28
Layers of the Heart
Endocardium:
Innermost/deepest layer of the heart
•
Lines the heart chambers and the
•
valves
•
Smooth thin lining to reduce friction of
• blood flow through the chambers
Cardiac conduction system located in this
layer
Image source – See slide 28
Layers of the Heart
Myocardium:
• Middle, thickest layer
of the heart
• Contains the muscle fibres
which are responsible for
pumping
• Contraction of this layer
allows blood to be pumped
through to the blood vessels
Image source – See slide 28
Physiology of
Cardiac Muscle
The heart is composed of three major types of cardiac
muscle:
1. Atrial muscle
2. Ventricular muscle
3. Specialized excitatory and conductive muscle fibers
The atrial and ventricular types of muscle contract in
much the same way as skeletal Muscle but the duration of
contraction is much longer.
The specialized excitatory and conductive fibers
contract only feebly because they contain few
contractile fibrils; instead, they exhibit either
automatic rhythmical electrical discharge in the form
of action potentials or conduction of the action
potentials through the heart.
Providing an excitatory system that controls the
rhythmical beating of the heart.
Chambers of the Heart
The heart is divided into
four chambers:
A: Right Atrium
V: Right
Ventricle
A: Left Atrium
V: Left Ventricle
Image source – See slide 28
Upper Chambers
The upper chambers are:
• The atria
- Right
- Left
Image source – See slide 28
Upper Chambers
The right atrium:
Receives deoxygenated blood
from the body through the:
• superior vena cava (head and
upper body)
• inferior vena cava (legs and
lower torso)
The left atrium:
Receives oxygenated blood from the
lungs through the:
• pulmonary veins
Image source – See slide 28
Lower Chambers
The lower chambers are:
• The ventricles
– Right
– Left
Image source – See slide 28
Lower Chambers
The right ventricle:
Receives de-oxygenated blood
as the right atrium contracts
The left ventricle:
Receives oxygenated blood
as the left atrium
LV contracts
RV
Valves of the
heart
The valves are located
within the chambers of the
heart.
The function of the valves:
Controls the direction of
blood flow
Allows one way flow of blood
- through chambers
- from the heart to the body
Image source – See slide 28
Valves of the
heart
The four valves are known as:
• the tricuspid valve
• the pulmonic or pulmonary valve
• the mitral valve
• the aortic valve
Image source – See slide 28
Valves of the heart
The tricuspid valve:
• Is an atrioventricular valve,
situated between the atria and the
ventricle
• Controls the opening between the
right atrium and the right ventricle
The mitral valve:
• Is an atrioventricular valve,
situated between the atria and the
ventricle
• Controls the opening between
the left atrium and the left
ventricle
Image source – See slide 28
Valves of the heart
The pulmonic or pulmonary valve:
• Is a semi lunar valve which controls
the blood leaving the heart
• Situated between the right ventricle
and the pulmonary artery
• Controls the flow of blood from the
right ventricle
• Prevents blood flow back to the
right ventricle, as it relaxes
Image source – See slide 28
Valves of the heart
The aortic valve:
• Is a semi lunar valve which
controls the blood leaving the
heart
• Controls blood flow between
the left ventricle and the
aorta
Image source – See slide 28
The Cardiovascular system
Cardiovascular System consists of the:
Heart
Lungs
Blood vessels
It includes:
pulmonary circulation
Systemic circulation
Image source – See slide 28
Pulmonary circulation
Pulmonary circulation is:
The carriage of oxygen-depleted blood
away from the heart to the lungs via the
pulmonary artery
The return of oxygen-rich blood to the heart
via the pulmonary vein
Image source – See slide 28
Pulmonary circulation
Pulmonary circulation and the heart
The inferior and superior vena cava carry oxygen depleted blood to the relaxed right atrium of
the heart
The right atrium contracts and blood travels through the tricuspid valve into the relaxed
right ventricle
The right ventricle contracts, the blood is pumped through the pulmonary valve into the
pulmonary artery to the lungs
Gas exchange occurs in the lungs
Co2 is released and oxygen is absorbed
Blood returned to the heart by pulmonary veins
Systemic circulation
Systemic circulation is:
• The carriage of oxygen-rich blood
away from the heart to the body
• The return of oxygen-depleted blood
back to the heart
Image source – See slide 28
Systemic circulation
Systemic circulation and the heart
• Oxygen rich blood travels from the lungs via the pulmonary veins to the
left atrium
• The left atrium contracts, and blood flows through the mitral valve into the
relaxed left ventricle
• The strong left ventricle contracts and pumps oxygen rich blood through
the aortic valve into the aorta
• The aorta carries blood to the organs of the body
