Across
- 4. a signal transmitted along a nerve fiber. It consists of a wave of electrical depolarization that reverses the potential difference across the nerve cell membranes.
- 6. a bacterium, virus, or other microorganism that can cause disease.
- 10. the state or quality of being resistant to a particular infectious disease or pathogen.
- 13. chemical messengers that your body can't function without
- 14. a branching figure (as in a mineral or stone) resembling a tree
- 17. a gap between the pre- and postsynaptic cells that is about 20 nm (0.02 μ) wide
- 18. a rapid sequence of changes in the voltage across a membrane
Down
- 1. a small colorless disk-shaped cell fragment without a nucleus, found in large numbers in blood and involved in clotting.ed
- 2. sit behind the ears and are the second largest lobe
- 3. a colorless cell that circulates in the blood and body fluids and is involved in counteracting foreign substances and disease; a white (blood) cell. There are several types, all amoeboid cells with a nucleus, including lymphocytes, granulocytes, monocytes, and macrophages.
- 5. treatment with a vaccine to produce immunity to a particular infectious disease or pathogen.
- 7. nerve cells that send messages all over your body to allow you to do everything from breathing to talking, eating, walking, and thinking
- 8. an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord
- 9. the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector)
- 11. a large phagocytic cell found in stationary form in the tissues or as a mobile white blood cell, especially at sites of infection.
- 12. a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
- 15. a blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances which the body recognizes as alien, such as bacteria, viruses, and foreign substances in the blood.
- 16. the electrical potential difference across the plasma membrane when the cell is in a non-excited state