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Cardiovascular system anatomy and physiology
Lymphatic system anatomy and physiology
Abnormal heart sounds
Normal heart sounds
Changes in pressure-volume loops
Cardiac and vascular function curves
Altering cardiac and vascular function curves
Law of Laplace
Measuring cardiac output (Fick principle)
Stroke volume, ejection fraction, and cardiac output
Physiological changes during exercise
Cardiovascular changes during hemorrhage
Cardiovascular changes during postural change
Cardiac conduction velocity
Electrical conduction in the heart
ECG normal sinus rhythm
ECG QRS transition
ECG rate and rhythm
ECG cardiac infarction and ischemia
ECG cardiac hypertrophy and enlargement
Control of blood flow circulation
Microcirculation and Starling forces
Blood pressure, blood flow, and resistance
Compliance of blood vessels
Laminar flow and Reynolds number
Pressures in the cardiovascular system
Resistance to blood flow
Action potentials in myocytes
Action potentials in pacemaker cells
Cardiac excitation-contraction coupling
Excitability and refractory periods
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Cardiac work, also known as stroke work, is similar to the concept of work in physics. In physics, work is defined as force times distance.
Stroke work can be thought of as the work performed by the left ventricle to eject a volume of blood, defined as stroke volume multiplied by mean aortic pressure.
And here, stroke volume corresponds to distance, whereas mean aortic pressure corresponds to force. Stroke work is best represented by a pressure-volume loop.
Pressure- volume loops are graphs, where the pressure inside the left ventricle is on the y axis and the volume of the left ventricle is on the x axis.
Each loop represents changes in ventricular pressure and volume over the course of one cardiac cycle, or one heartbeat, which includes both ventricular systole, or contraction, and diastole, or relaxation.
The lower right hand corner is the end-diastolic point, and it’s the point in the cardiac cycle when diastole is over. Αt this point, the mitral valve between the left atrium and the left ventricle, closes, leaving the left ventricle filled with the maximum volume of blood, called the end-diastolic volume.
And then, systole begins, which is when the left ventricle contracts to push that blood into the aorta. Ventricular contraction makes the pressure shoot up, but for a brief period of time, both the mitral and aortic valves are closed, so left ventricular volume doesn’t change.
The cardiac cycle, also called the stroke work, is the work performed by the heart's left ventricle during an ejection of a blood volume. It is the performance of the heart from the beginning of one heartbeat to the beginning of the next, and equals to the product of the mean aortic pressure and stroke volume, which is the amount of blood pumped by the left ventricle in one beat. Cardiac work done in a full minute will be referred to as cardiac minute work. It is equal to the product of mean aortic pressure and cardiac output, since the cardiac output equals heartbeats in one minute times the stroke volume.
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