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Cardiovascular System:
The Heart
Heart Development
I. Introduction
Functions of the
Cardiovascular System:
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Transportation:
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Respiratory gasses
Nutrients
Waste
Hormones
Regulation of temperature
Protection (immune system)
Components of the
Cardiovascular System
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Cardiovascular System = heart and the
vessels
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Lymphatic system = lymph vessels, lymph
nodes, lymph organs
Heart Anatomy
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General Features:
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Size
It's a dual pump
Coverings of the Heart:
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Parietal pericardium
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Pericardial sac
Visceral
pericardium
(epicardium)
Heart in Cross-Section
Epicardium
(visceral
pericardium)
Myocardium
Endocardium
Chambers of the Heart
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Atria receive blood
Ventricles pump blood
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Right ventricle pumps blood to the
pulmonary circuit
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Left ventricle pumps oxygenated blood to
the systemic circuit
NOTE: Arteries Always carry blood Away
from the heart
Heart Valves
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Atrioventricular(AV) valves prevent backflow from
ventricles to atria
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Tricuspid valve
Bicuspid valve (mitral valve)
Chordae tendineae originate from papillary muscles
Semilunar valves
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Aortic semilunar valve
Pulmonary semilunar valve
Cardiac Circulation
Electrical Events
in the Heart
Compare and Contrast
Skeletal vs. Cardiac Muscle
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Purpose
Basic principles (all-or-none)
Time
Summation / Tetanus
Refractory period
Source of stimulus / role of NS
Extrinsic Regulation
Autonomic nervous system
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Sympathetic system
Parasympathetic
Intrinsic regulation
(nodal system)
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Sinoatrial (SA) node contains pacemakers
Atrioventricular (AV) node
Atrioventricular bundle (Bundle of His)
Bundle branches
Purkinje fibers
The Cardiac Cycle
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Cardiac cycle = contraction, relaxation cycle
of the heart
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Systole = contraction
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Cardiac Output = heart rate x stroke
volume
Diastole = relaxation
Stroke volume = volume of blood ejected
by a ventricle as it contracts
The Cardiac Cycle
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1. Atrial and Ventricular Diastole
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Atria are filling with blood, AV valves are open and
blood passively fills the ventricles.
2. Early Ventricular Systole
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Ventricles begin to contract, forcing the AV valves to
close
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Isovolumic ventricular contraction: ventricles
contract, but AV and semilunar valves are closed
The Cardiac Cycle
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3. Ventricular Systole and Blood Ejection
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When ventricular contraction generates enough
pressure to open the semilunar valves, blood enters the
arteries
4. Ventricular Diastole
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Ventricles relax, pressure decreases
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Blood flows back into the heart, closing the semilunar
valves
Blood remaining in ventricles is called end-diastolic
volume, EDV
Electrocardiogram
(ECG)
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P wave = atrial depolarization
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T wave = repolarization of ventricles
QRS wave = depolarization of ventricles (and
repolarization of atria).
Arteriosclerosis and
Cardiac Arrhythmia
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Plaques can clog the arteries, causing
restricted blood flow
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Smoking, hypertension, and a diet high in
cholesterol and fats contribute
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High ratio of HDL to LDL is desirable
Myocardial ischemia
Myocardial infarction = heart attack.
Tight stenosis of RCA.
This can cause an
inferior wall myocardial
infarction. Since this is
a short lesion, usually
percutaneous coronary
intervention will be used
- balloon dilatation &
stinting.
Cardiac Arrhythmias
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Arrhythmias
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Bradycardia = heart rate less than 60 beats/ min
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Fibrillation = rapid, uncontrolled contractions
Tachycardia = heart rate more than 100 / min
Flutter = rapid, controlled contractions of atria or
ventricles
Electrical defibrillation can sometimes re-regulate
the myocardial cells to become synchronous again.