| A | B |
|---|
| cell | The basic unit of structure and function in all living things. |
| nucleus | Organelle that controls all of the cell's activity. |
| cell membrane | Thin covering that encloses a cell and keeps its parts together. |
| cytoplasm | A jellylike substance containing chemicals that help keep a cell functioning. |
| diffusion | The process by which many materials move in and out of the cell. |
| osmosis | The diffusion of water and dissolved materials through a cell membrane. |
| receptors | Nerve cells that detect conditions in the body's environment. |
| tissue | Cells that work together to perform a specific function. |
| organ | Tissues that work together to perform a specifc function. |
| system | Organs that work together to perform a function. |
| villi | Tiny tubes sticking into the small intestine that absorb nutrients into the blood. |
| capillaries | The smallest blood vessels. |
| alveoli | tiny air sacs, located at the end of bronchi in the lungs, through which gases are exchanged with the blood. |
| bone marrow | Connective tissue that producess red and white blood cells. |
| nephrons | Tubes inside the kidneys where urea and water diffuse from the blood. |
| joints | Places where bones meet and are attached to each other and to muscles. |
| tendons | Tough bands of connective tissue that attach muscles to bones. |
| ligaments | Bands of connective tissue that hold a skeleton together. |
| neuron | A specialized cell that can receive information and transmit it to other cells. |
