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Blood Flow and Volume
The heart pumps about all of the body's blood volume (5 liters) through the body in one minute. Blood volume measurements can be taken to assess heart function:
- Stroke volume (SV) - volume of blood pumped out of the heart with each beat (average volume is 70ml)
- Cardiac output (CO) - volume of blood pumped out in one minute
How could you calculate CO if you know the heart rate and the stroke volume?
Image 15: Vascular System
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Watch Video: Heart and Circulatory System (3:04) to view how blood flows through the heart's chambers and valves at a resting adult heart rate (Beats per minute, BPM = 72).
Go to the Anatomy of the Heart from Wisc-Online and click through the animation to view structures and blood flow.
Arteries of the Heart
Coronary arteries supply blood to the heart muscle. Like all other tissues in the body, the heart muscle needs oxygen-rich blood to function. The image below shows the arteries of the heart (coronary arteries).
Image 16: Heart and Coronary Arteries
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There are 2 main arteries supplying blood to the heart muscle itself:
- Right Coronary Artery (RCA) – supplies blood to right side of the heart
- Left Main Coronary Artery (LMCA) – supplies blood to the left side of the heart
- Left Anterior Descending (LAD)
- Circumflex
Coronary Arteries
Since coronary arteries deliver blood to the heart muscle, any coronary artery disorder or disease can have serious implications by reducing the flow of oxygen and nutrients to the heart muscle.
This reduction in oxygen can lead to a heart attack (also known as myocardial infarction) and possibly death.
Atherosclerosis, or a buildup of plaque in the inner lining of an artery causing it to narrow or become blocked, is the most common cause of heart disease.
This image shows the coronary arteries injected with a dye for visualization using fluoroscopy (a special type of X-ray). Any blockages would be visible using this test.
Image 17: Coronary Artery Test
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Plaque Build Up
This image shows a comparison of coronary artery lumens.
Image 18: Plaque Build Up
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Limiting Blood Flow
This image illustrates the narrowing of the artery lumen due to plaque and limiting blood flow. If complete blockage occurs, a heart attack will be the result.
Image 19: Atherosclerosis
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Check your understanding...
What is your cardiac output if your heart rate is 80 bpm and your stroke volume is 70 ml?
If your heart rate increases, what will happen to your cardiac output?
The main arteries supplying blood to the heart muscle are the ___________ and the __________.
