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-Introducing our Planet-
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Systems within Systems within Systems The first step towards understanding how Earth works is thinking about our planet as a system. We use the word "system" when we want to describe something that is made up of different kinds of parts that join together to form an interconnected whole. Learning to think in terms of systems is very useful because we are surrounded by all sorts of systems. In fact, each of us is our own little system. Each of us is made up of more than 200 kinds of cells. These nerve, skin, muscle, bone, red blood and gland cells all join together to form an incredible system - an individual human person. All the structures that these cells form - our skin, muscles, bones, blood vessels, internal organs - function as an interconnected whole. Looking at ourselves as a system reveals two important features of systems:
Each part of a system can itself be described as a system. You are a system. One of the parts of the "you system" is the way blood moves throughout your body - in other words, your circulatory system. This circulatory system is part of the bigger "you system" but it itself is a system with many parts. The parts of the circulatory system include heart, veins, arteries and blood cells. The heart, a part of the circulatory system, is also a system made of parts. Its parts include muscle cells, nerve cells and valves. A heart muscle cell is part of the heart system but it is also a system which is made up of a cell membrane, cell nucleus and many different proteins. |