| A | B |
|---|
| cell | basic unit of structure and function of all living things |
| cell membrane | thin cell covering that holds the parts of the cell together |
| nucleus | organelle that controls a cell's activities |
| cytoplasm | jellyike substance that contains many chemicals to keep a cell functioning |
| diffusion | process by which particles of a substance move from an area where there are many particles to an area where there are fewer particles of the substance |
| osmosis | movement of water and dissolved materials through the cell membrane |
| tissue | cells that work together to perform a specific function |
| organ | tissues that work together |
| system | organs that work together to perform a function |
| capillaries | small tubes that transport blood between the arteries and the veins |
| alveoli | tiny air sacs |
| villi | tiny tubes sticking out of the wall of the small intestine |
| nephrons | small structures in the kidneys through which urea and water travel from the blood |
| bone marrow | the soft center of bones that produces red and white blood cells |
| tendons | tough bands of tissue that attach bones to muscles |
| ligaments | tough bands of tissue that attach bones to each other |
| neurons | special cells that transmit and receive nervous-system signals |
| receptors | special nerve cells that detect conditions in the body's environment |
