NUTRITION
THE HUMAN BODY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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sitting
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standing
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kneeling
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lying down
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Detailed explanation-1: -Because veins have to work against gravity to get blood back to the heart, contraction of skeletal muscle assists with the flow of blood back to the heart.
Detailed explanation-2: -Normally the pressure on the right side of the heart and in the pulmonary arteries is lower than the pressure on the left side of the heart and in the aorta. This is because: the right side of the heart pumps blue (deoxygenated – little or no oxygen) blood returning from the body back to the lungs.
Detailed explanation-3: -In many body regions, the pressure within the veins can be increased by the contraction of the surrounding skeletal muscle. This mechanism, known as the skeletal muscle pump (Figure 6), helps the lower-pressure veins counteract the force of gravity, increasing pressure to move blood back to the heart.