3. LOCATION
• Size of a fist
• Between your lungs behind sternum
• Slightly towards left of midline (ie sternum)
4.
5. • Superior vena cava returns the
venous blood from the head,
neck and upper limbs.
• Inferior vena cava that returns
the venous blood from lower
parts of the body.
• Both reach right atrium.
• Right atrium communicates with
the right ventricle through the
tricuspid valve. Venous blood
from the right atrium enters the
right ventricle through this valve.
• From the right ventricle, pulmonary artery arises. It
carries the venous blood from right ventricle to the
lungs. In the lungs, the deoxygenated blood is
oxygenated.
6. • Left atrium receives
oxygenated blood from the
lungs through pulmonary
veins.
• Blood from left atrium enters
the left ventricle through the
mitral valve (bicuspid valve).
• Left ventricle pumps the
arterial blood to different parts
of the body through systemic
aorta.
8. • Pericardium has 2 layers and a fluid is present bw them.
• Myocardium is the middle layer of the wall of the heart
and it is formed by cardiac muscle fibers. It forms the
bulk of the heart and it is responsible for the pumping
action of the heart.
Myocardium is formed by three types of cardiac muscle
fibers:
i. Muscle fibers which form the contractile unit of the
heart.
ii. Muscle fibers which form pacemaker.
iii. Muscle fibers which form the conductive system.
Endocardium continues as endothelium of the blood
vessels.
Heart is made up of three layers of tissues:
1. Outer pericardium.
2. Middle myocardium.
3. Inner endocardium.
There are four valves in human heart. Two of the valves are in between the atria and the
ventricles called atrioventricular valves. The other two are the semilunar valves, placed
at the opening of the blood vessels arising from the ventricles, i.e. systemic aorta and
pulmonary artery
9. ACTIONS OF THE HEART
• The actions of the heart are classified into four
types:
• 1. Chronotropic action
• 2. Inotropic action Force of contraction of heart. Types:
i. Positive inotropic action or
increase in the force of contraction.
ii. Negative inotropic action or
decrease in the force of contraction.
Frequency of heartbeat or heart rate.
Types:
i. Tachycardia or increase in heart
rate.
ii. Bradycardia or decrease in the
heart rate.
10. • 3. Dromotropic action
• 4. Bathmotropic action
Conduction of impulse through heart.
i. Positive dromotropic action or
increase in the velocity of conduction.
ii. Negative dromotropic action or
decrease in the velocity of conduction.
Excitability of cardiac muscle
i. Positive bathmotropic action or
increase in the excitability of cardiac
muscle.
ii. Negative bathmotropic action or the
decrease in the excitability of cardiac
muscle.
11. Systemic and pulmonary circulation
SYSTEMIC CIRCULATION
It is otherwise known as greater circulation. The blood pumped from left ventricle passes
through a series of blood vessels of arterial
system and reaches the tissues. Exchange of various
substances between blood and the tissues takes place in
the capillaries. After the exchange of substances in the
capillaries, the blood enters the venous system and
returns to right atrium and then the right ventricles.
PULMONARY CIRCULATION
It is otherwise called lesser circulation. Blood is pumped from right ventricle to lungs through
pulmonary artery. The exchange of gases occurs between blood and alveoli of the lungs
through pulmonary capillary membrane. The oxygenated blood returns to left atrium through
the pulmonary veins.
12. CARDIAC CYCLE
- Cardiac cycle is defined as the sequence of coordinated
events in the heart which are repeated during every
heartbeat in a cyclic manner. Each heartbeat consists of two
major periods called systole and diastole. Systole is the
contraction of the cardiac muscle and diastole is the
relaxation of cardiac muscle.
- This consists of
• Atrial events which constitute atrial systole and atrial diastole.
• Ventricular events which constitute ventricular systole and
ventricular diastole.
• However, in clinical practice, the term ‘systole’ refers to
ventricular systole and ‘diastole’ refers to ventricular diastole.
13. - When the heart beats at the normal rate of
72/minute, the duration of each cardiac cycle
is about 0.8 second.
- Atrial systole occurs during the last phase of
ventricular diastole. Atrial diastole is not
considered as a separate phase, since it
coincides with whole of ventricular systole and
earlier part of ventricular diastole.
14. HEART SOUNDS
• Heart sounds are the sounds produced by the mechanical activities
of the heart during each cardiac cycle. Generally, heart sounds are
produced by:
1. Flow of blood through the chambers of the heart.
2. Contraction of cardiac muscle.
3. Closure of valves of the heart.
• The heart sounds are heard by placing the ear over the chest or by
using a stethoscope or microphone. These sounds are also recorded
graphically.
• Four heart sounds are produced during each cardiac cycle. The first
and second heart sounds are called classical heart sounds. These
sounds are more prominent and resemble the spoken words ‘LUB’
and ‘DUB’ respectively.
15. First heart sound Second heart sound Third heart sound Fourth heart sound
Closure of
atrioventricular
valves
Closure of semilunar
valves
Rushing of blood into
ventricle
Contraction of atrial
musculature
LUB sound DUB sound Low pitched Inaudible sound
Coincides with
peak of R’ wave
Precedes or appears
0.09 second after peak
of ‘T’ wave
Between ‘T’ wave
and ‘P’ wave
Between ‘P’ wave
and ‘Q’ wave
P
Q
R
S
T
16. Conditions when Third Heart Sound becomes Audible by
Stethoscope
• Third heart sound can be heard by stethoscope in children and
athletes. Pathological conditions when third heart sound becomes
loud and audible by stethoscope are
1)Aortic regurgitation (leaking of the aortic valve of the heart that
causes blood to flow in the reverse direction during ventricular
diastole, from the aorta into the left ventricle)
2)Cardiac failure and cardiomyopathy with dilated ventricles.
• When third heart sound is heard by stethoscope the condition is
called triple heart sound. Third heart sound is usually heard best
with the bell of stethoscope placed at the apex beat area when the
patient is in left lateral decubitus (lying on left side) position.
17.
18. • Conditions when Fourth Heart Sound becomes Audible
• Fourth heart sound becomes audible by stethoscope when the
ventricles become stiff. Ventricular stiffness occurs in conditions like
ventricular hypertrophy, long-standing hypertension and aortic
stenosis. To overcome the ventricular stiffness, the atria contract
forcefully producing audible fourth heart sound.
• When fourth heart sound is heard by stethoscope the condition is
called triple heart sound. It is usually heard best with the bell of
stethoscope placed at the apex beat area when the patient is in
supine or left semilateral position.
19. METHODS OF STUDY OF HEART SOUNDS
Heart sounds are studied by three methods:
1. By using stethoscope.
2. By using microphone.
3. By phonocardiogram.
BY USING STETHOSCOPE – AUSCULTATION AREAS
• The first and second heart sounds are heard on the
auscultation areas by using the stethoscope. The
chest piece of the stethoscope is placed over 4 areas
on the chest, which are called auscultation areas.
The four auscultation areas are detailed below.
20.
21. BY MICROPHONE
• A highly sensitive microphone is placed over the chest. The
heart sounds are amplified by means of an amplifier and
heard by using a loudspeaker. First, second and third heart
sounds are heard by this method.
BY PHONOCARDIOGRAM
• Phonocardiography is the technique used to record the heart
sounds. Phonocardiogram is the graphical record of the heart
sounds. It is done by placing an electronic sound transducer
over the chest. This transducer is connected to a recording
device like polygraph. All the four heart sounds can be
recorded in phonocardiogram. It helps to analyze the
frequency of the sound waves
Generally, the ECG and PCG signals are concurrent
phenomena, in which the former is the electrical signal while
the latter is the mechanical signal.
