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The HEART
Anatomy and Physiology
Introduction
• Triangular shape
• Size of your fist
• Located between the lungs in lower
portion of mediastinum behind sternum
• 2/3 of mass to left of sternum
• Blunt end is called apex and points toward
left
• Site where heart sounds are best heard
Heart Chambers
• Organ is hollow
• Divided into right and left sides
• Contains four hollow chambers
– Atria- top chambers or receiving chambers
– Ventricles-lower chambers or discharging
chambers
• Atria are smaller than ventricle
• Have right and left atria as well as right and
left ventricles
Layers of Heart
• Endocardium- inner most layer of thin
smooth tissue
• Myocardium-middle muscular layer
• Pericardium-outer layer that consist of two
layers of fibrous tissue
– Visceral Pericardium or epicardium- inner layer
of pericardium
– Parietal Pericardium- loose fitting covering on
the outside of the heart
• Epi-upon or on
Endo-within or in
Chambers of the Heart
Diseases of Layers
• Endocarditis-inflammation or infection of
inner layer of heart
• Thrombosis- blood clot
– Caused by endocardial lining becoming rough
and abrasive to RBC’s passing over its surface.
– As blood flows over a rough surface clots are
subject to form
• Embolis-blood clot that is flowing in blood
stream
• Pericarditis-inflammation or infection of
pericardium
Diseases of Layers
• Pericardial Effusion-when pericardial fluid,
pus of blood may accumulate in the space
between two pericardial layers and impairs
the pumping action of the heart
• Cardiac Tamponade- when pericardial
effusion gets worse and develops a serious
compression of the heart
• Myocarditis-infection or inflammation of
myocardium
Heart Valves
• Atrioventricular Valves-separate the atria
from the ventricles
– Triscupid valve- between right atrium and
ventricle
– Bicuspid or Mitral valve-between left atrium and
ventricle
– Prevents backflow of blood into the atria when
the ventricles contract
– Chordae tendineae-attaches AV valves to the
wall of the heart
Atrioventricular Valves
Heart Valves
• Semilunar Valves-located between the two
ventricular chambers and large arteries that
carry blood away from the heart
– Pulmonary semilunar valve- located between
right ventricle and pulmonary artery
– Aortic semilunar valve- located between left
ventricle and aorta
– Both valves prevent backflow of blood into
ventricles
Disorders of Valves
• Incompetent valves-allow some blood to flow
back into the chamber from which it came
• Stenosed Valves- valves that are narrower
than normal, slowing blood flow from a heart
chamber
• Mitral Valve Prolapse- (MVP) when the flaps
of the Mitral valve extend back into the left
atrium, causing incompetent valves
Semilunar Valves
Heart Action
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Heart is a muscular pumping device
Systole- contraction of the heart
Diastole relaxation of the heart
When heart beats→atria contract first
(atria systole)→forcing blood into
ventricles
• Once filled→two ventricles contract
(ventricular systole)→blood forced out of
heart
Blood Flow Right Side
• Enters heart through Superior/Inferior
Vena Cava
– Blood is oxygen poor from the body
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Goes to Right Atrium
Through Tricuspid Valve
Into Right Ventricle
Through Pulmonary Valve
To Pulmonary Artery and into lungs
Blood Flow Left Side
• From lungs where O2 is added and CO2
removed goes to
• Left Atrium then through
• Mitral Valve to the
• Left Ventricle then through
• Aortic Valve to the
• Aorta where it is carried to all parts of the
body
Anatomy of Heart
Heart Sounds
• Heart with stethoscope on anterior wall of
chest
• Rhythmic and repetitive sounds “Lub dub”
• First sound or lub-caused by vibration and
abrupt closure of AV valves as ventricles
contract
• Longer sound with a lower pitch
• Second sound or dub-caused by closure
of semilunar valves during diastole
Heart Sounds
• Heart Murmurs-abnormal heart sounds caused
by disorders of valves
• Incompetent valves cause a swishing noise as a
“lub” or Dup” ends
• Stenosed valves, often cause swishing sounds
just before “lub” or “dup”
Coronary Circulation
• Heart muscle or myocardium requires on
going supply of blood to function
• Coronary circulation-the delivery of oxygen
and nutrient rich arterial blood to the cardiac
muscle and removal of oxygen-poor blood
from the active tissue to the venous system
• Blood flows into the heart muscle by way of
two small vessels called Right Coronary
Artery and Left Coronary Artery
Coronary Circulation
Coronary Circulation
• Coronary arteries are the first branches of
the aorta
• Myocardial Infarction or heart attack occurs
when one of these arteries are occluded
with a blood clot or plaque
– Tissue death occurs when area is deprived of
oxygen
• Atherosclerosis- “hardening of the arteries”
due to a build up of lips or other substances
inside walls of blood vessels
Coronary Diseases
• Angina Pectoris-Severe chest pain due
that occurs when the myocardium is
deprived of oxygen
– Usually a warning sign that the arteries are no
longer able to supply enough blood and
Oxygen to the heart muscle
• Coronary Artery Bypass Graft-Surgery to
bypass a damaged or occluded coronary
artery
Conduction System
• Cardiac muscles are coordinated by
electrical impulses
• Has it’s own built in conduction system that
is embedded into wall of the heart to
generate and conduct impulses
• Sinoatrial Node- SA Node-sometimes called
the “natural Pacemaker” of the heart
• Atrioventricular Node-AV node- sends
impulses from atria to ventricles
Conduction System
• http://video.about.com/heartattacks/Electro
cardiogram.htm
Conduction System
• AV Bundle or Bundle of HIS- sends
impulses down middle of ventricles
• Purkinje Fibers-carries impulses around
the outsides of the ventricles
• Ventricular beats always follows each atria
beat
• If this does not occur then you have Heart
Blocks
Conduction System
Normal Electrocardiograph
Cardiac Arrhytmias
Cardiac Arrhythmia
• Arrhythmia-an abnormal heart rhythm
• Heart Block-type of arrhythmia where the
impulses are blocked from transmitting
– AV Node Block-Blocked from getting to the
ventricular myocardium
– Complete Heart Block-occurs when the P
waves do not match up with the QRS as seen
on an ECG
Cardiac Arrhythmia
• Bradycardia- slow heart rate, most often
caused by defective SA node
• Tachycardia-fast heart rate, improper
autonomic control of the heart
• Sinus arrhythmia-variation of heart rate
during breathing cycle
– Heart rate increases with inspiration and
decreases with expiration
Cardiac Arrhythmia
• Premature Contractions- contractions that
occur before the next expected contraction
in a series of cardiac cycles
– Premature Atrial Contraction- may occur
shortly after the ventricles contract
– Premature Junctional Contraction-may occur
before the AV node fires
– Premature Ventricular Contraction-may occur
before the Bundle of HIS contracts
Cardiac Arrhythmia
• Fibrillation-a condition in which cardiac
muscle fibers contract out of step with each
other
– Atrial Fibrillation-common in elderly, can be
treated with medications or defrillation
– Ventricular Fibrillation- life-threatening condition
in which defribillation is a must
• Flutter-when cardiac fibers flutter instead of
contracting
• http://www.madsci.com/manu/ekg_rhy.htm
Heart Failure
• Inability to pump enough returned blood to
sustain life
• Right-sided heart failure-failure of the right
side of the heart to pump blood, usually
because the left side is not pumping
effectively
• Left-Sided heart failure- Congestive Heart
Failure-inability of left ventricle to pump
effectively