3D-HuBEd No.5 -HEART-

The heart is at a little bit left side of the chest. It circulates blood through the body like a pump. It is divided into the left and the part by the septum. In each of them the atrium is separated from the ventricle by valves. This means that a heart consists of four parts, the left and right atriums and the left and right ventricles.

This is the cycle of a heart's movement. First, the left and right atrium contracts to pump blood into ventricles. Next, ventricles contracts and blood in them is pushed into the lung or the whole body. Blood given oxygen in the lung goes to the left atrium through the pulmonary artery and then it circulates through the whole body. Blood lost oxygen returns to the right ventricle and from there it goes to the lung via the pulmonary artery and gets oxygen again.

The Number of beats of a heart is normaly about 70 times per a minute. When a man takes exercise or feels nervous, sometimes the number goes up 200 per a minute.

Refer to chapter 0 for more information on how to use this textbook.

　　5.1 The structure of the heart

　　5.2 The beat of the heart

5.1 The structure of the heart

the 3-D figure with the name: $HOME/hubed/yyHeart2.tar.gz

[Four rooms of the heart]

A male's heart weighs 280 grams (female's one is 230 grams). It is like a sack made of muscles and has four rooms. The right and left rooms are separated by septums and the up-and-down rooms are partitioned by valves. The left atrium is joined thr pulmonary vein. The right atrium is joined the vena cava. In a heart, some valves work to decide the direction of blood flow. There is a mitral valve between the left atrium and the left ventricle, and there is a tricuspid valve between right atrium and right ventricle. The aortic valve situated between the left ventricle and the aorta, and the pulmonary valve situated between theright ventricle and the pulmonary atery.

[Muscles of the heart]

The heart muscle consists of two layers in atriums and consists of three layers in ventricles.

The structure of heart muscle fiber is like striated muscle same asthe skeletal muscle. Heart muscles are different from ordinary striated muscles. Their diameters are less than about 15 micro meters. Muscle fibers form fine tree structures and the twigs are connected with each other.

The structures about the relation of cross striations and muscle filaments is same as the skeletal muscle's structure.

[Blood]

Blood consists of the erythrocytse(red blood corpusclse), the leucocytse(white blood corpusclse), the thrombocytse(blood platelest), lymphocyte, and the blood plasma. Blood's works are follows:

carriage oxygen and carbon dioxide (erythrocyte and blood plasma)
carriage nourishmentst,hormonese and so on (blood plasma)
killing bacteria (leucocyte)
covering injury (thrombocyte)

Blood always circulates through the whole body. All required exchanges are done between blood and all the cells.

5.2 The beat of the heart

The heart is the pump for the circulation of blood. Blood sent to the lung casts off carbon dioxide and gets oxygen, and then returns to the heart. This is the pulmonary circulation. The blood circulates through the body and supply cells with oxygen and gets carbon dioxide. This is the systematic circulation.

the 3-D figure with the name: $HOME/hubed/yyHeart1.tar.gz

The heart works as a pump which is the power of blood circulation, by voluntary contracts and movement of valves. When heart beat 75 times per a minute, the heartbeat sequence period is about 0.8 second, and the ventricle contraction and dilation period is 0.35 second and 0.45 second each. Of corse, these periods change depend on the situation of body or individual difference. We can know the condition of the heart by theelectronicl transition of muscle movements, transformation of the heart or the sound of valves' open and close.

the 3-D figure with the name: $HOME/hubed/yyFFD.tar.gz