Troposphere.
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In an oligopoly type of market, there are only few producers whom dominate the market. This is the market type wherein there are only small number of firms that control the majority of the market share. The opposite to Perfect Competition, wherein there are unlimited number of producers. In an oligopoly, since there are only a few numbers competitors, each firm is likely to be aware of each other's action.
The three mechanisms which regulate the heart are endocrine, cardiovascular and Sinoatrial nodes.
The endocrine system consists of the glands and hormones of the human body. The cardiovascular system is the organ system which is responsible for the circulation of the blood around the body and the oxygenation of the body's tissues. The sinoatrial node (SA node) generates the electrical impulses and is considered the natural pacemaker of the heart.
