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Southwestern Illinois
EMS System
Introduction to
Cardiac
Anatomy and Physiology
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Introduction
• Cardiovascular disorder
– Diseases, conditions that involve heart, blood
vessels
• Heart disease
– Conditions affecting heart
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Introduction
• Coronary heart disease
– Coronary arteries, resulting complications
• Angina pectoris, acute MI
• Coronary artery disease
– Affects arteries that supply heart muscle with
blood
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Risk Factors &
Prevention Strategies
• Risk factors
– Nonmodifiable (fixed) risk factors
– Modifiable risk factors
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High blood pressure
Elevated serum cholesterol levels
Tobacco use
Diabetes
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Risk Factors &
Prevention Strategies
• Risk factors
– Modifiable risk factors
• Physical inactivity
• Obesity, body fat distribution
• Metabolic syndrome
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Risk Factors &
Prevention Strategies
• Risk factors
– Contributing risk factors
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Stress
Inflammatory markers
Psychosocial factors
Alcohol intake
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Cardiovascular Anatomy
& Physiology
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Anatomy Review
• Blood vessels
– Arteries
– Arterioles
– Capillaries
– Venules
– Veins
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Anatomy Review
• Heart anatomy
– Location
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Mediastinum
Behind sternum, above diaphragm
Base
Apex
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Anatomy Review
Heart Location
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Anatomy Review
• Heart anatomy
– Heart chambers
• Upper chambers
– Right, left atria
• Lower chambers
– Right, left ventricles
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Anatomy Review
• Heart anatomy
– Septum
– Pulmonary circulation
– Systemic circulation
– Blood carried from heart to body through arteries,
arterioles, capillaries
– Blood returned to heart through venules, veins
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Anatomy Review
Heart anatomy
• Heart layers
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Endocardium
Myocardium
Epicardium
Pericardium
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Anatomy Review
• Heart anatomy
– Heart valves
• AV valves
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Separate atria from ventricles
Tricuspid valve, between right atrium, right ventricle
Mitral/bicuspid valve lies between left atrium, left ventricle
Open when forward pressure forces blood forward
Close when backward pressure pushes blood backward
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Anatomy Review
• Heart anatomy
– Atrial kick
• Blood flows continuously into atria
• 70% flows directly through, into ventricles before atria
contract
• When atria contract, additional 30% added to filling of
ventricles
• When ventricles contract (systole), pressure rises
• Tricuspid, mitral valves close when pressure within
ventricles exceeds that of atria
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Anatomy Review
• Heart anatomy
– Semilunar (SL) valves
• Pulmonic, aortic valves
• Prevent backflow of blood from aorta, pulmonary
arteries into ventricles
• Close as ventricular contraction ends, pressure in
pulmonary artery, aorta exceeds that of ventricles
• Chordae tendinae, connective tissue, attached to AV
valves underside & papillary muscles
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Anatomy Review
• Blood flow through heart
– Enters right atrium via superior, inferior venae cavae,
coronary sinus
– Right atrium through tricuspid valve into right ventricle
– Right ventricle expels blood through pulmonic valve into
pulmonary trunk
– Flows through pulmonary arteries to lungs
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Anatomy Review
• Blood flow through heart
– Low in O2, passes through pulmonary capillaries
– From left atrium through mitral valve into left
ventricle
– Distributed throughout body through aorta, its
branches
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Anatomy Review
• Blood flow through heart
– Tissues of head, neck, upper extremities via
superior vena cava
– Lower body via inferior vena cava
– Superior, inferior vena cava carry contents into
right atrium
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Anatomy Review
• Cardiac cycle
– Repetitive pumping process, events associated
with blood flow through heart
– Systole
– Diastole
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Anatomy Review
• Cardiac cycle
– Depends on cardiac muscle ability to contract,
condition of heart’s conduction system
– Pressure with each chamber rises in systole, falls
in diastole
– Conduction system provides timing of events
between atrial, ventricular systole
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Anatomy Review
• Coronary arteries
– Right, left
– Main arteries
– Left anterior descending (LAD), left circumflex
(LCX), right coronary artery (RCA)
– Lie on outer surface of heart
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Anatomy Review
Coronary Arteries
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Anatomy Review
• Coronary veins
– Travel alongside arteries
– Coronary sinus, largest vein, drains heart
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Anatomy Review
• Heart rate
– Affected by sympathetic, parasympathetic ANS
– Chronotropic effect
– Inotropic effect
– Dromotropic effect
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Anatomy Review
• Heart rate
– Baroreceptors
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Specialized nerve tissue (sensors)
Found in internal carotid arteries, aortic arch
Detect changes in blood pressure
When stimulated cause sympathetic/parasympathetic
response
• Will “reset” to new “normal” after few days of
exposure to specific pressure
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Anatomy Review
• Heart rate
– Chemoreceptors
• In internal carotid arteries, aortic arch, medulla detect
changes in concentration of hydrogen ions (pH), O2,
carbon dioxide in blood
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Anatomy Review
• Heart rate
– Parasympathetic stimulation
• Parasympathetic fibers supply sinoatrial node, atrial
muscle, & AV junction of heart by vagus nerves
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Anatomy Review
• Heart rate
– Sympathetic stimulation
• Sympathetic nerves supply specific areas of heart’s
electrical system, atrial muscle, ventricular myocardium
• When stimulated, norepinephrine released
• Increases in heart rate shorten all phases of cardiac
cycle
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Anatomy Review
• Heart rate
– Increases in heart rate shorten all phases of
cardiac cycle
– Electrolyte, hormone levels, medications, stress,
anxiety, fear, body temperature can influence
heart rate
– Heart rate increases when body temperature
increases, decreases when body temperature
decreases
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Heart as Pump
• Venous return
– Most important factor determining amount of
blood pumped out by heart is amount of blood
flowing into right heart
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Heart as Pump
• Cardiac output
– Amount of blood pumped into the aorta each
minute by heart
– Defined as stroke volume x heart rate
– Stroke volume determined by
• Preload
• Afterload
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Heart as Pump
• Cardiac output
– Frank–Starling’s law
• Greater the volume of blood in heart during diastole
(preload), the more forceful cardiac contraction & more
blood ventricle will pump (stroke volume)
• Important that heart adjust its pumping capacity in
response to changes in venous return
• During exercise, heart muscle fibers stretch in response
to increased volume (preload) before contracting
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Heart as Pump
• Cardiac output
– Frank–Starling’s law
• Factors that increase cardiac output include increased
body metabolism, exercise, age & size of body
• Factors that may decrease cardiac output include
shock, hypovolemia, heart failure
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Conclusion
Please complete the 10 question online exam
and submit when completed.
Thank You
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Southwestern Illinois EMS System