Nutrition, Transportation, Respiration and Excretion
Nutrition, Transportation, Respiration and Excretion
Nutrition, Transportation, Respiration and Excretion
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Life Processes-1 <strong>Nutrition</strong>, <strong>Transportation</strong>, <strong>Respiration</strong> <strong>and</strong> <strong>Excretion</strong><br />
22.8 TRANSPORTATION IN HUMAN BEINGS<br />
MODULE - 5<br />
The Living World<br />
Human circulatory system consists of<br />
(i)<br />
(ii)<br />
Centrally located muscular pump called heart, <strong>and</strong><br />
Blood vessels, which are tube-like<br />
structures, connected to the heart<br />
(Fig.22.6).<br />
Notes<br />
Blood vessels are of three kinds:<br />
• Arteries: Carry blood from heart<br />
to various parts of body.<br />
• Veins: Bring blood from various<br />
parts of body to the heart.<br />
• Capillaries: Thin vessels<br />
between the artery <strong>and</strong> the vein.<br />
The capillaries allow the exchange<br />
of materials between blood <strong>and</strong><br />
tissues.<br />
Fig. 22.6 Arteries, veins <strong>and</strong> capallaries<br />
(iii) Circulating fluid—blood, tissue fluid <strong>and</strong> lymph<br />
22.8.1 Heart<br />
Heart is a powerful muscular organ lying between lung. It is four-chambered- two (right<br />
<strong>and</strong> left) atria (sing. atrium, also called auricles), <strong>and</strong> two (right <strong>and</strong> left) ventricles. (Fig.<br />
22.7a).<br />
Fig. 22.7(a) The human heart<br />
The heart is made of specialised muscle cells, also called cardiac muscle fibers,<br />
which contract <strong>and</strong> relax all the time without getting tired. The contraction <strong>and</strong><br />
SCIENCE AND TECHNOLOGY<br />
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