Functional Anatomy of Heart
Dr.Mohammed Sharique Ahmed Quadri
Assistant Professor Physiology
Almaarefa College
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FUNCTIONAL ANATOMY OF HEART
• Heart beat starts in the fourth week after
conception during intra-uterine life, when
embryo is only few millimeters.
• Throughout life, heart keeps on beating and it
contracts about 3 billion times during an
average life span.
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Circulatory System
• Three basic components
– Heart
• Serves as pump that establishes the pressure gradient
needed for blood to flow to tissues
– Blood vessels
• Passageways through which blood is distributed from
heart to all parts of body and back to heart
– Blood
• Transport medium within which materials being
transported are dissolved or suspended
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CIRCULATORY SYSTEM
• We have two types of circulation:
i). Pulmonary Circulation
ii). Systemic Circulation
 Pulmonary Circulation
Blood is carried from the right ventricle of the
heart to lungs and back to left atrium of the heart.
 Systemic Circulation
Blood is carried from left ventricle to the
body and back to the right atrium.
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Circulatory System
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FUNCTIONAL ANATOMY OF HEART
• Heart is muscular organ. It is involuntary, present
in the middle of the thoracic cavity, about the size
of fist [14cm long, 9cm wide].
• Sternum lies anteriorly and vertebral column
[backbone] lies posteriorly and lungs laterally.
• Heart has base and apex.
- Base is at the top, behind the 2nd intercostal
space.
- Apex is lower down in the 5th left intercostal
space. Slightly below nipple towards mid line
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FUNCTIONAL ANATOMY OF HEART
 Applied
• As the heart lies between the sternum and
vertebral column, it is possible to compress
the sternum and drive blood out of the heart
when heart is not pumping effectively.
• This external compression of heart is done in
CPR [Cardio-Pulmonary Resuscitation], which
is life saving, till proper therapy can be given.
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Circulatory System
• Heart IS A Dual pump
– Right and left sides of heart function as two
separate pumps
– Divided into right and left halves and has four
chambers
• Atria
– Upper chambers
– Receive blood returning to heart and transfer it to
lower chambers
• Ventricles
– Lower chambers which pump blood from heart
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HEART AS A PUMP
• Right and left atrium are separated from each
other by interatrial septum.
• Right and Left ventricle are separated by
interventricular septum.
[Septum is muscular wall which does not
allow the blood to mix between two sides.]
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HEART AS A PUMP
• In between atria and ventricle, there is fibrous
ring, in which valves are embedded.
• Right atrium gets the blood from superior
venaceva [SVC] and inferior venaceva [IVC]. It
is deoxygenated blood.
• Blood from right atrium goes to right ventricle
through right AV valve or Tricuspid valve.
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HEART AS A PUMP
• From right ventricle, blood goes to pulmonary
artery through pulmonary valve, to the lungs.
• In the lungs, blood gets oxygenated and is
returned to left atrium by 4 pulmonary veins.
 IMPORTANT
 Remember  Pulmonary Artery is the only
artery which carries deoxygenated blood and
Pulmonary veins are only veins in the body which
carry oxygenated blood.
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HEART AS A PUMP
• From left atrium, blood goes to left ventricle
through left AV valve or mitral valve [bicuspid
valve].
• From left ventricle, blood goes to aorta
through aortic valve to the body.
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COMPARISON OF RIGHT & LEFT
PUMPS
RIGHT PUMP
• Both sides pump equal
amount of blood.
• Right side has deoxygenated
blood [goes to lungs and gets
O2 in the lungs] .
• Pulmonary Circulation is low
pressure circulation.
• Pulmonary Circulation is low
resistance circulation.
• Right ventricle wall is thin
[2-3mm].
•
•
•
•
•
LEFT PUMP
Both sides pump equal
amount of blood.
Left side has oxygenated
blood.
Systemic Circulation is high
pressure circulation.
Systemic Circulation is high
resistance circulation.
Left ventricle wall is thick
[8-10mm].
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HEART VALVES
• There are four valves.
• They are one way valve.
• Valves open and close passively because of
pressure difference.
• Function of the valve is to prevent back flow
of the blood.
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HEART VALVES
• Four Valves are:
Two AV [Atrioventricular] Valves
i). Right AV Valve – Tricuspid Valve
ii). Left AV Valve – Mitral or Bicuspid Valve
Semi lunar Valves
iii). Aortic Valve
iv). Pulmonary Valve
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Heart valves
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AV VALVES
• AV Valves [Tricuspid & Mitral] are attached to the
papillary muscle and chordae tendineae.
• Chordae tendineae are tendon like tissue and their
function is prevent the eversion or bulging of valves
into atria.
• Chordae tendineae are attached to papillary muscle
which protrude from inner surface of ventricular valve.
• Important -- Papillary muscle and chordae tendineae
are attached to AV valves only.
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AV VALVES
• When ventricle contract, papillary muscle also
contract and pull down the chordae
tendineae, which keeps the valve tightly
closed.
• There are three papillary muscles attached to
the right AV valve [tricuspid valve].
• There are two papillary muscle attach to the
left AV valve [bicuspid or mitral valve].
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SEMI-LUNAR VALVES
 Aortic Valve and Pulmonary Valve
• Aortic Valve is present at the beginning of aorta and
has three cusps.
• Pulmonary Valve is present at the beginning of
pulmonary artery and has three cusps.
• Aortic and Pulmonary Valve open when pressure
increases in left and right ventricle during ventricular
contraction.
• They close when ventricular pressure decreases than
aortic and pulmonary artery pressure.
• They prevent back flow of the blood.
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Heart Valves
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FIBROUS SKELETON OF THE HEART
• In between atria and ventricles, there is fibrous
ring [it is dense connective tissue].
• It provides base for attachment of four heart
valves.
• Atrial Muscle is attached to upper part and
ventricular muscle is attached to the bottom of
the ring.
• Fibrous ring is non-conductive, therefore, special
conductive tissue is required to conduct impulse
from atria to ventricle.
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FIBROUS SKELETON OF THE HEART
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LAYERS OF THE HEART
• Heart has 3 Layers:
1. Endothelium – inner lining of the heart
2. Myocardium – cardiac muscle tissue
3. Pericardium – external layer
• Pericardium has two layers inner visceral [called
epicardium] and outer parietal layer.
• There is pericardial fluid about 5 – 30 ml present
between two layers. It prevents friction between
the layers as they move over each other with
every beat of the heart.
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APPLIED - PERICARDITIS
• Pericarditis is the inflammation of
pericardium.
• It results in painful friction rub between the
two layers of pericardium.
• It can be caused by viral or bacterial infection.
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BLOOD SUPPLY TO THE HEART
• Heart is supplied by coronary arteries
[branches of aorta].
• Cardiac muscle fibers have rich blood supply,
about 1 capillary for each myocardial fiber.
• Cardiac muscle has abundance of energy
generating mitochondria.
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AUTONOMIC NERVE SUPPLY
• Heart is supplied by sympathetic and
parasympathetic nerves.
• Sympathetic Stimulation causes increased force
of contraction [positive INOTROPIC effect] and
increase heart rate [positive CHRONOTROPIC
effect].
• Parasympathetic Stimulation decreased force of
contraction [negative INOTROPIC effect] and
decrease in heart rate [negative CHRONOTROPIC
effect].
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CARDIAC MUSCLE
MICROSCOPIC STRUCTURE
• Cardiac Muscle fibers are connected by
membrane called ‘INTERCALATED DISC’.
• Intercalated Disc have gap junction.
• Gap Junction allow relatively free diffusion of
ions, therefore, action potential travels from one
cell to another easily.
• Therefore, cardiac muscle works as SYNCYTIUM
[one unit], therefore, heart can be depolarized all
at one time, it obeys all or none law.
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Cardiac Muscle Fibers
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CARDIAC MUSCLE
MICROSCOPIC STRUCTURE
• We have Atrial Syncytium and Ventricular
Syncytium. They contract as separate units as
they are separated by non-conducting fibrous
ring.
• The impulse travels from the atria to the
ventricle by specialized conductive tissue.
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References
• Human physiology by Lauralee Sherwood,
seventh edition
• Text book physiology by Guyton &Hall,11th
edition
• Text book of physiology by Linda .s
contanzo,third edition
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