8 May
2009

‘Have a heart!’ you’ll hear somebody say. Or ‘he’s all heart!’ Ever said that to anyone?

We all know the body has a heart. Often it’s equated with emotions. ‘Heart-throb’ and ‘heart-break’ are common words which relate feelings to this important part of the body. Although the ancients believed the heart had something to do with life, they also related it to psychological sensations. Of course, it has nothing to do with emotional feelings, although if there are moments of tension or anxiety, the heart will often begin to bang away. This is because the brain sends out impulses to the adrenal glands via the nervous system. In turn, a chemical called adrenaline is pumped into the system. One of its many functions is

to accelerate the heart rate. So, the banging heart and the wildly thumping chest in moment of fright or distress.

The heart is simply one massive muscle which acts as a pump. Its job is to keep the body’s blood circulation active for 24 hours a day. It does this with perfect agility, often for 70 or 80 years or more, beginning a few months after conception. The heart is formed during the first three months following conception, and the baby’s prenatal circulation is soon established.

The heart consists of four chambers, which are referred to as atria and ventricles. There is one of each on each side of the heart, commonly referred to as the right side and the left side.

Blood comes from all parts of the body via a system of collecting lubes called veins. These finally empty into one large tube which enters the right atrium through a valve. The chamber is filled, and at the next heart beat, as the muscle squeezes tightly, the blood is forced through another valve into the right ventricle, a fairly large chamber which accommodates the blood. When the beat stops, the valve snaps shut. At the next beat, this blood is pumped through another valve into a large short tube called the pulmonary artery. This conveys the blood to the lung system.

Here carbon dioxide is released from the blood, and a fresh supply of oxygen taken aboard; the bluish-coloured blood suddenly turns a bright fiery red. At the next pump, the blood flows back via another short tube, called the pulmonary vein, to the left side of the heart.

It gains access to the left atrium, once more via a special valve which conveniently opens for a short time to allow the blood entry. At the next pump, the blood flows from the left atrium to the large left ventricle via another connecting valve. Finally, as the heart pumps again, this refreshed, vigorous, oxygen-rich blood pours forth via another valve into the aorta, a huge artery much the size and shape of a piece of hose pipe.

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