The Function/Components of the HEART



The Function/Components of the HEART

What is the function of the heart?

The heart is a pump that distributes blood to the organs of the body. The heart is made of 4 chambers. The top 2 collecting chambers are called atria; the bottom 2 ejecting chambers are called ventricles.

The right atrium receives blood deficient in oxygen from the body and sends it into the right ventricle. The right ventricle squeezes the blood out to the lungs to pick up fresh oxygen. The oxygenated blood returns from the lungs to the left atrium, which then funnels the blood into the left ventricle. The left ventricle ejects the oxygenated blood into the entire body via the aorta.

What are the major components of the heart?

The heart is made of a contracting muscle that generates the force required to transport blood to all parts of the body. The muscle contracts from the bottom up to eject the blood into the aorta. The aorta branches out into a network of blood vessels that distributes blood to the organs of the body.

In the heart, there are 4 valves that allow the blood to move in 1 direction only. For example, the aortic valve opens when the ventricle contracts and closes immediately when the heart relaxes, preventing the blood from returning back to the left ventricle.

In addition to the muscle and the valves, the heart is made of a complex electrical system that allows the muscle to pump continuously and predictably. Electrical impulses are generated from a site in the right atrium called the sino-atrial node. This serves as the natural pacemaker of the heart, generating electrical impulses at the normal resting rate of 60 to 100 beats per minute. At a rate of 60 beats per minute, the heart contracts approximately 31,536,000 beats per year.

What are heart sounds and murmurs?

Heart sounds are generated from the closure of the valves. There are 2 normal heart sounds. One is generated from closure of the mitral and tricuspid valves when the heart contracts and is called S1. The second heart sound is generated from the closure of the aortic and pulmonic valves when the heart relaxes and is called S2.

Abnormal heart sounds can be generated in the setting of heart failure (S3) or from a very stiff ventricle, such as in the setting of long-standing high blood pressure or heart attacks (S4).

What are the veins?

Once the nutrients and oxygen are delivered to an organ, the blood needs to return to the heart to start the cycle over again. The capillary branches rejoin, forming larger, flexible vessels capable of holding blood. These collecting blood vessels are called veins. The small veins link up to become larger veins. The larger veins eventually lead back to the atria of the heart via the inferior vena cava (the main vein carrying blood to the heart from the lower body) or the superior vena cava (the main vein carrying blood from the upper body, especially the head). Unlike the artery, the vein has very little muscle layer. Also, 1-way valves help the blood to flow in 1 direction toward the heart through the veins. Incompetence of these valves can lead to varicose veins and accumulation of fluid in the legs upon sitting or standing for long periods of time.

The Function/Components of the HEART Review Questions

DIRECTIONS Answer each of the questions below using complete sentences.

1. How many normal heart sounds are there?

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2. What is the function of the aorta?

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3. What are the ejecting chambers called?

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4. What is the heart’s purpose?

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5. How many times approximately does the heart contract per year?

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6. What structure receives blood that is oxygen deficient?

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7. What are veins?

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8. Your heart is a _____________?

9. What is the difference between the inferior vena cava and the superior vena cava?

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10. What are the top two collecting chambers called?

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