Cells, Tissues, Organs and Systems
Cell Theory
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Anything that’s alive is made up of at least one cell.
The cell is the basic unit of life.
All cells come from previously existing cells.
Tissues – when cells group together to carry out a specific function, they’re called tissues. There are four types:
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Muscle tissue is long, and can expand and contract easily (like an elastic band).
Epithelial tissue is packed tightly together, and forms the protective layers for the outside of your organs, and your skin.
Connective tissue holds our bodies together. Picture bits of fruit suspended in jello.
Nervous tissue, which can sense and send signals around your body.
Organs – when tissues group together to perform a specific function, they’re called organs.
Systems – when organs work together to perform specific functions we refer to that as a system. Examples are the circulatory system,
nervous system, etc. Although they each have their own job(s) they all depend on each other.