Across
- 2. are nerve cells that transmit an action potential.
- 4. part of the nervous system, controlling the muscles and glands, that is not under voluntary control
- 6. a process extending from a neurone that conducts action potentials away from the cell body.
- 9. one of a number of chemicals that are involved in communication between adjacent neurones or between nerve cells and muscles. Two important examples are acetylcholine and noradrenaline.
- 12. a section of myofibril between two Z-lines that forms the basic structural unit of skeletal muscle.
- 13. a hormone produced by a cells of the islets of Langerhans in the pancreas that increases blood glucose levels by initiating the breakdown of glycogen to glucose.
- 14. is the potential difference in electrical charge across the cell surface membrane of a nerve cell when the cell is at rest.
- 17. is found in the alimentary canal and the walls of blood vessels. Its contraction is not under conscious control. See also skeletal muscle.
- 18. is part of the retina that has no rod cells but large numbers of cone cells.
- 20. change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulse passes.
- 22. propagation of a nerve impulse along a myelinated dendron or axon in which the action potential jumps from one node of Ranvier to another.
- 24. a cell adapted to detect changes in the environment.
- 25. the maintenance of a more or less constant internal environment.
- 26. a hormone produced by the adrenal glands in times of stress that prepares the body for an emergency.
- 28. an area of heart muscle in the right atrium that controls and coordinates the contraction of the heart. Also known as the pacemaker.
Down
- 1. depolarisation of the membrane of a receptor cell as a result of a stimulus.
- 3. an organ that responds to stimulation by a nerve impulse resulting in a change or response.
- 5. is a growth response made by a plant in response to an external stimulus.
- 7. are the small fibres that are arranged parallel to each other in a skeletal muscle fibre.
- 8. is the short recovery period that occurs immediately after the passage of a nerve impulse along the axon of a nerve cell.
- 10. is a non-conducting fatty layer around the neurone.
- 11. the portion of the nephron that forms a hairpin loop that extends into the medulla of the kidney. It has a role in the reabsorption of water.
- 12. a junction between neurones in which they do not touch but have a narrow gap
- 15. a condition that results from the core body temperature rising above normal.
- 16. emporary reversal of charges on the cell-surface membrane of a neurone that takes place when a nerve impulse is transmitted.
- 19. substance made up of a carbohydrate molecule and a protein molecule.
- 21. belongs to a class of plant growth factors called auxins.
- 23. tough, flexible, but inelastic, connective tissue that joins muscle to bone. See also ligament.
- 27. one of a group of chemicals, called neurotransmitters, released by neurones. It diffuses across the gap (synapse) between adjacent neurones and so passes an impulse from one neurone to the next.