Describe the insulating sheaths on axons and dendrites in the nervous systems. How do these help to speed transmission of neural messages?
What will be an ideal response?
Nonneural cells called glial cells wrap around axons (or dendrites) many times, so their wrapping is literally multiple layers of plasma membranes (lipids). In many parts of the nervous system, these cells are called Schwann cells, and the wrapping is the myelin sheath around the axon. This causes the neural message to skip from node to node (nodes are in between adjacent cells). This jumping, called saltatory conduction, results in a much more rapid conduction of nerve impulses.
You might also like to view...
For many years, no one bothered to test the food-competition hypothesis for why giraffes have long necks. Why?
A) It had been much too difficult to test. B) The hypothesis was so plausible that no one thought to question it. C) They tried, but the results were inconclusive. D) The hypothesis did not make clear predictions that could be tested.
No asteroids have orbits that cross the Earth's orbit
a. True b. False Indicate whether the statement is true or false
A red blood cell ____
a. does not possess a nucleus b. is made in the plasma c. can divide in the plasma d. has the ability to repair itself e. lives up to 120 months
Which of the following will occur when a plant is placed into a hypotonic solution?
A. It will wilt. B. Some of its cells will burst. C. Turgor prevents more water from entering the cells. D. Water is actively pumped out of the cells. E. Elastic fibers in the cell walls enable plant cells to stretch and accommodate more water.