Cardiovascular System
Heart
Introduction of Cardiovascular Sytem

1.
2.
3.
Consists of;
Blood
Heart
Blood Vessels
Location of Heart

Heart lies between the lungs in the
mediastinum.
Location of Heart

Two-thirds of its mass is to the left of the
midline
Location of Heart

Precordium – The area of the chest
anterior to the heart
Location of Heart

Lies between the vertebral column and the
sternum
Structure and Function of Heart
1.
2.
Pericardium
Layers of the Heart Wall
Pericardium

The heart is enclosed and held in place by
the pericardium
Pericardium

1.
2.
Consists of;
Fibrous pericardium (outer)
Serous pericardium (inner)
Pericardium

Fibrous pericardium – anchors the heart
in the mediastinum
Pericardium

1.
2.
Serous pericardium composed of;
Parietal layer
Visceral layer
Pericardium

Pericardial cavity – a space between the
parietal and visceral layers filled with
pericardial fluid
Layer of the Heart
1.
2.
3.
Epicardium
Myocardium
Endocardium
Epicardium

Consists of the visceral layer of
pericardium and connective tissue
(adipose)
Myocardium

Composed of cardiac muscle
Myocardium

The cells are branched, involuntary, and
have one nucleus
Myocardium

The cells are connected by intercalated
discs, which have gap junctions that allow
ions to flow in between cells during
depolarization
Endocardium

Lines the chambers and covers the
connective tissue in the heart valves
Endocardium

It consists of endothelium
Chambers of the Heart
1.
2.
3.
4.
Right Atrium
Right Ventricle
Left Atrium
Left Ventricle
Chambers of the Heart

On the surface of the heart are auricles
and sulci
Chambers of the Heart

Auricles – small pouches on the anterior
surface of each atrium
Chambers of the Heart

Sulci – Are grooves that contain coronary
arteries and fat and separate the
chambers
Right Atrium

1.
2.
3.
The right atrium receives systemic
venous blood from;
Superior Vena Cava
Inferior Vena Cava
Coronary sinus
Right Atrium

The atrium receives blood low in O2 and
high in CO2
Right Atrium

Interatrial septum - separates the right
and left atria
Right Atrium

Fossa ovalis – an oval depression in the
interatrial septum; it is a remnant of the
foramen ovale
Right Atrium

Tricuspid Valve – Blood passes from the
right atrium into the right ventricle
through here
Right Ventricle

Forms most of the anterior surface of the
heart
Right Ventricle

Pulmonary semilunar valve - Blood passes
from the right ventricle to the pulmonary
trunk via this valve
Left Atrium

Receives pulmonary venous blood from
the pulmonary veins which is rich in
oxygen and low in CO2
Left Atrium

Mitral Valve – Blood passes from the left
atrium to the left ventricle via this valve
Left Ventricle

Thickest and strongest chamber
Left Ventricle

Forms the apex of the heart
Left Ventricle

Blood passes from the left ventricle
through the aortic valve into the aorta
Left Ventricle

During fetal life the ductus arteriosus
shunts blood from the pulmonary trunk
into the aorta
Left Ventricle

At birth the ductus arteriosus closes and
becomes the ligamentum arteriosum
Left Ventricle

The left ventricle is separted from the
right ventricle by the interventricular
septum
Myocardial Thickness and Function

The atria walls are thin because they only
pump blood to the nearby ventricles
Myocardial Thickness and Function

The ventricle wall are thicker because they
pump blood greater distances
Myocardial Thickness and Function

The right ventricle walls are thinner than
the left because they pump blood to the
nearby lungs
Myocardial Thickness and Function

The left ventricle walls are thicker because
they pump blood through the body
Function of Heart Valves

Valves open and close in response to
pressure changes as the heart contracts
and relaxes
Myocardial Thickness and Function

1.
2.
Two types of valves;
Atrioventricular Valves
Semilunar
Atrioventricular Valves
1.
2.
Tricuspid (right side)
Mitral or bicuspid (left side)
Atrioventricular Valves

AV valves prevent blood flow from the
ventricles back into the atria
Atrioventricular Valves

Back flow is prevented by the contraction
of papillary muscles and tightening the
chordae tendinae
Semilunar Valves

SL valves allow ejection of blood from the
heart into the pulmonary arteries and
aorta
Semilunar Valves

Prevent back flow into the ventricles
Circulation of Blood
1.
2.
3.
Systemic
Pulmonary
Coronary
Systemic Circulation

The left side of the heart pumps
oxygenated blood from the left ventricle
into the ascending aorta.
Systemic Circulation

The coronary arteries arise off of the
ascending aorta
Pulmonary Circulation

The right side of the heart receives
deoxygenated blood from the body.
Pulmonary Circulation

The right side of the heart pumps blood
from the right ventricle and sends it into
the lungs via the pulmonary artery
Circulation of Blood

Right atrium receives blood from the
superior and inferior vena cava
Circulation of Blood

The Left atrium receives blood from the
pulmonary veins
Coronary Circulation

It delivers oxygenated blood and nutrients
to and removes CO2 and wastes from the
myocardium
Coronary Circulation

The left and right coronary
arteries branch from the ascending
aorta and carry oxygenated blood
Coronary Circulation

1.
2.
Left coronary artery branches into the;
Left anterior descending artery
Circumflex artery
Coronary Circulation

1.
2.
Right coronary artery branches into;
Marginal artery
Posterior descending artery
Coronary Circulation

Deoxygenated blood returns to the right
atrium through the coronary sinus
Histology of Cardiac Muscle

In comparison to skeletal muscle fibers,
cardiac muscle fibers are involuntary,
shorter in length, larger in diameter, and
squarish rather than circular in transverse
section.
Histology of Cardiac Muscle

They also exhibit branching
Histology of Cardiac Muscle

Have same arrangement of actin and
myosin, and the same bands, zones, and Z
discs as skeletal muscles
Cardiac Conduction System

There is an atrial and ventricular network
Cardiac Conduction System

Fibers within the networks are connected
by intercalated discs
Cardiac Conduction System

The intercalated discs allow the fibers to
work together so that each network serves
as a functional unit
Cardiac Conduction System

Cardiac muscle cells are autorhythmic cells
because they are self-excitable.
Cardiac Conduction System

They repeatedly generate spontaneous
action potentials that then trigger heart
contraction
Cardiac Conduction System

1.
2.
3.
4.
5.
The components of this system are;
Sinoatrial node (SA)
Atrioventricular node (AV)
Bundle of His
Right and Left Bundle branches
Purkinje fibers
Cardiac Conduction System

SA node is the pacemaker
Cardiac Conduction System

From the SA node, a cardiac action
potential travels throughout the atrial
muscle and down to the AV node
Cardiac Conduction System

At the AV node the impulse is delayed
(about 0.1sec)
Cardiac Conduction System

This gives the atria time to completely
contract before ventricular contraction
begins
Cardiac Conduction System

It then passes through the Bundle of His,
Right and Left Bundle Branches, and the
Purkinje fibers, resulting in ventricular
contraction
Cardiac Cycle

1.
2.
Consists of;
Systole (contraction) and Diastole
(relaxation) of both atria
Systole and Diastole of both ventricles
Atrial Diastole

The atria are relaxed
Atrial Diastole

They receive blood from three veins
Atrial Diastole

The A-V valves are open, allowing for 70%
of ventricular filling. The ventricles are
therefore also in diastole.
Atrial Systole

The SA node then fires; after this electrical
event, atrial systole begins (a mechanical
event)
Atrial Systole

Atrial contraction accounts for 30% of
ventricular filling
Ventricular Systole

Shortly after the beginning of ventricular
depolarization, ventricular systole begins
Ventricular Systole

The ventricles contract. The ventricular
pressure becomes higher than atrial
pressures, causing the AV valves to close.
Ventricular Systole

The SL valves open when the ventricular
pressure becomes higher than aortic
(pulmonary arterial) pressure.
Ventricular Systole

Then blood is ejected into the aorta and
pulmonary trunk.
Ventricular Diastole

Begins when the ventricles relax
Ventricular Diastole

Ventricular pressures drop below arterial
pressures, causing the SL valves to close
Ventricular Diastole

The ventricular pressures continue to drop
below atrial pressures, causing the AV
valves to open
Auscultation

Listening to sounds within the body with a
stethoscope
Auscultation

The first heart sound (lubb) is created by
the closing of the AV valves soon after
ventricular systole begins
Auscultation

The second heart sound (dupp) represents
the closing of the SL valves close to the
end of the ventricular systole.
Cardiac Output

The volume of blood ejected from the left
ventricle (or the right ventricle) into the
aorta (or pulmonary trunk) each minute.
Cardiac Output

Cardiac Output = Stroke volume X Heart
Rate
Cardiac Output

Stroke volume – the volume of blood
ejected by the ventricle with each
contraction
Cardiac Output

Stroke Volume = End Diastolic Volume
(130ml) – End Systolic Volume (60ml)
Cardiac Output

Heart Rate – number of beats per minute
Regulation of Heart Rate

Sympathetics impulses increase heart rate
and force of contraction
Regulation of Heart Rate

Parasympathetic impulses decrease heart
rate
Tachycardia

Heart Rate over 100 beats/min
Bradycardia

Heart Rate below 60 beats/min
Fibrillation

Prolonged tachycardia
Exercise And The Heart

Sustained exercise increases oxygen
demand in muscles
Exercise And The Heart

Resting cardiac output 5.25 Liters/minute
Exercise And The Heart

In sedentary people CO may go up to 22
liters/minute
Exercise And The Heart

In trained athletes CO may go up to 40
liters/minute
Exercise And The Heart

Sedentary people increase their CO during
exercise by an increase in HR and SV
Exercise And The Heart
Sedentary people
 Increase in HR more dramatic
 Stroke volume only goes up by 10-35%

Exercise And The Heart

For a given activity, sedentary people’s
maximum HR will be higher than in a
trained athlete
Exercise And The Heart

Trained athletes increase their CO during
exercise by an increase in HR and SV
Exercise And The Heart
Trained Athletes
 Increase in SV more dramatic than HR
 Their SV goes up to 60%

Exercise And The Heart

Athletes have larger stroke volumes due to
longer filling time
Electrocardiogram (ECG or EKG)

Records the electrical currents of the body
generated by the heart
Electrocardiogram (ECG or EKG)

P= depolarization of the atria
Electrocardiogram (ECG or EKG)
QRS= depolarization of the ventricles
(repolarization of atria, but don’t see)

Electrocardiogram (ECG or EKG)

T= ventricles repolarization
Electrocardiogram (ECG or EKG)

PR interval= between beginning of atrial
depolarization and ventrical depolarization
Electrocardiogram (ECG or EKG)

ST segment= ventricle contraction
Electrocardiogram (ECG or EKG)

QT interval = ventricle depolarization
through ventricle repolarization