topic 6

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Across
  1. 2. are nerve cells that transmit an action potential.
  2. 4. part of the nervous system, controlling the muscles and glands, that is not under voluntary control
  3. 6. a process extending from a neurone that conducts action potentials away from the cell body.
  4. 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.
  5. 12. a section of myofibril between two Z-lines that forms the basic structural unit of skeletal muscle.
  6. 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.
  7. 14. is the potential difference in electrical charge across the cell surface membrane of a nerve cell when the cell is at rest.
  8. 17. is found in the alimentary canal and the walls of blood vessels. Its contraction is not under conscious control. See also skeletal muscle.
  9. 18. is part of the retina that has no rod cells but large numbers of cone cells.
  10. 20. change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulse passes.
  11. 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.
  12. 24. a cell adapted to detect changes in the environment.
  13. 25. the maintenance of a more or less constant internal environment.
  14. 26. a hormone produced by the adrenal glands in times of stress that prepares the body for an emergency.
  15. 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. 1. depolarisation of the membrane of a receptor cell as a result of a stimulus.
  2. 3. an organ that responds to stimulation by a nerve impulse resulting in a change or response.
  3. 5. is a growth response made by a plant in response to an external stimulus.
  4. 7. are the small fibres that are arranged parallel to each other in a skeletal muscle fibre.
  5. 8. is the short recovery period that occurs immediately after the passage of a nerve impulse along the axon of a nerve cell.
  6. 10. is a non-conducting fatty layer around the neurone.
  7. 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.
  8. 12. a junction between neurones in which they do not touch but have a narrow gap
  9. 15. a condition that results from the core body temperature rising above normal.
  10. 16. emporary reversal of charges on the cell-surface membrane of a neurone that takes place when a nerve impulse is transmitted.
  11. 19. substance made up of a carbohydrate molecule and a protein molecule.
  12. 21. belongs to a class of plant growth factors called auxins.
  13. 23. tough, flexible, but inelastic, connective tissue that joins muscle to bone. See also ligament.
  14. 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.