Human Body

No 1 Every Human Body is Made up of Trillions of Cells

A snowman is built up of trillions of tiny snowflakes stuck together .The human body also made of trillions of tiny pieces. But instead of snowflakes, we are made of things called cells. Cells are the building blocks of all living things. But the cells your skin is made up of are different from that made up of your blood. Your bones are made up of yet another kind. Even though there are different types of cells, they are still all cells. Therefore, they must have some things in common.
What is that makes a cell? Every cell is like a city. Cities can be very different from one another, but they still have things in common. All cities have boundaries around them. Each cell has a membrane around it, which acts like a protective wall. The nucleus, found in most cells, is like the cell’s city hall-it manages how the cell operates. Like the bust streets of a city, the cytoplasm is the place where all the work of the cell is done. This is the material between the nucleus and the cell membrane.

Red blood cells are one exception; they do not have a nucleus.


No 2 Shapes and sizes of cells

Most cells are so small that they can only be seen with a microscope. In animals, an average cell is 0.0004 inch across. Shapes of cells vary. Some look like columns, others are cubes. The cells in your cheek are flat, and nerve cells look like long threads.

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