From a cell to you

About this video

A football team is not eleven goalkeepers. Each player has a job, the players form groups, and the groups together make a team. A body is organised in a similar way, starting from cells.

A bacterium has to do everything itself. In a many-celled body, cells share the work: each kind of cell is shaped for one job. These are specialised cells, and your body has at least 200 kinds. Red blood cells are small and round and carry oxygen. Nerve cells are long and thin and carry messages, some of them about a metre long, from your back to your toes. Muscle cells are long and can shorten, which is how you move. Skin cells are flat and fit together like tiles to cover and protect you.

Do these cells carry different DNA? No: almost every cell in your body carries the same full set of instructions. A skin cell and a nerve cell differ because each uses a different part of them, like two cooks using different pages of the same recipe book.

Biologists describe a body in five levels, each built from the one before: a cell, such as a heart muscle cell; a tissue, many similar cells working together, such as heart muscle; an organ, made of two or more kinds of tissue with a job of its own, such as the heart; an organ system, organs working together, such as the heart and blood vessels; and the organism, the whole living thing: you. Plants have the same levels, from the cells that catch light to leaves, stems and roots. The human body has eleven organ systems, and they depend on each other.

This video goes with the lesson From Cells to Organisms in Biology Level 1 on Knaph.

Transcript

1. 0:00A football team is not eleven goalkeepers. Each player has a job, and the players form groups. Your body works the same way.
2. 0:09In a many-celled body, cells share the work. Red blood cells carry oxygen. Nerve cells carry messages, some about a metre long. Muscle cells shorten, so you move. Skin cells fit together like tiles. You have at least 200 kinds.
3. 0:30Do skin cells and nerve cells carry different DNA? No. Almost every cell has the same instructions. Each uses different pages of the same recipe book.
4. 0:42Biologists describe a body in five levels. A cell. Many similar cells working together make a tissue, like heart muscle. Tissues make an organ, like the heart. Organs working together make an organ system, like the heart and blood vessels. And all the systems make an organism. You.
5. 1:10Plants have the same levels, from cells to leaves to the whole plant. And your body has eleven organ systems, all depending on each other.
6. 1:20Cells make tissues, tissues make organs, organs make systems, and the systems make you.