Chapter 3. All about the Heart
Chapter 3. All about the Heart. The blood circulatory system is one of the most vital systems in human beings and other higher animals because this system supplies nutrition all over the body for metabolic activities. Blood circulatory system consists of blood, heart and blood vessels. The heart is formed by cardiac muscles. It is a triangular vacuum chambered and pumps like the organ. Blood is circulated by its expansion and contraction. Blood vessels are of three kinds according to shape, structure and function i,e, – artery, vein, and capillary.
Chapter 3. All about the Heart
The heart works like a pump in humans and other animals for circulating blood through vessels. Oxygenated blood is circulated in the whole body through the artery. Normally carbon dioxide-rich blood returns to the heart from different parts of the body through veins. The connecting site of the artery and vein is the capillary system. We will discuss blood in detail in this chapter.
We see and hear about hearts everywhere. A long time ago, people even thought that their emotions came from their hearts, maybe because the heart beats faster when a person is scared or excited. Now we know that emotions come from the brain, and in this case, the brain tells the heart to speed up. So what’s the heart up to, then? How does it keep busy? What does it look like? Let’s find out.
Your heart is really a muscle. It’s located a little to the left of the middle of your chest, and it’s about the size of your fist. There are lots of muscles all over your body — in your arms, in your legs, in your back, even in your behind.
But the heart muscle is special because of what it does. The heart sends blood around your body. The blood provides your body with the oxygen and nutrients it needs. It also carries away waste.
Your heart is sort of like a pump or two pumps in one. The right side of your heart receives blood from the body and pumps it to the lungs. The left side of the heart does the exact opposite: It receives blood from the lungs and pumps it out to the body.
How does the heartbeat? Before each beat, your heart fills with blood. Then its muscle contracts to squirt the blood along. When the heart contracts, it squeezes — try squeezing your hand into a fist. That’s sort of like what your heart does so it can squirt out the blood. Your heart does this all day and all night, all the time. The heart is one hard worker!
The heart is made up of four different blood-filled areas, and each of these areas is called a chamber. There are two chambers on each side of the heart. One chamber is on the top and one chamber is on the bottom. The two chambers on top are called the atria (say: AY-tree-uh). If you’re talking only about one, call it an atrium. The atria are the chambers that fill with the blood returning to the heart from the body and lungs. The heart has a left atrium and a right atrium.
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