Plz solve these two question ....
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It is the question of DAV, class7th
Answers
2. As a central part of the circulatory system, the heart is primarily responsible for pumping blood and distributing oxygen and nutrients throughout the body. Because of this task, the heart may be considered one of the most important organs of the body, such that even small dysfunctions or abnormalities may cause drastic changes or effects in the human organism.
The heart is a muscle whose working mechanism is made possible by the many parts that operate together. The organ is divided into several chambers that take in and distribute oxygen-poor or oxygen-rich blood. These chambers are accompanied by veins and arteries that facilitate the same function. With all of its parts working together towards the same goal, the heart successfully pumps blood with ease.
Normally, a good-functioning adult heart could go on three cardiac cycles or 72 beats per minute. This rate changes for children whose heart rates are normally and relatively faster.
3. There are three main types of blood vessels:
This vast system of blood vessels -- arteries, veins, and capillaries -- is over 60,000 miles long. That's long enough to go around the world more than twice!
Blood flows continuously through your body's blood vessels. Your heart is the pump that makes it all possible.
Arteries. Arteries carry oxygen-rich blood away from the heart to all of the body's tissues. They branch several times, becoming smaller and smaller as they carry blood farther from the heart and into organs.
Capillaries. These are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide, and other waste products to pass to and from cells.
Veins. These are blood vessels that take blood back to the heart; this blood contains less oxygen and is rich in waste products that are to be excreted or removed from the body. Veins become larger as they get closer to the heart. The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart.
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