Neurons+JO


 * Neurons**

1. Insert an image of the basic neuron structure that includes cell body, dendrites, and axon. p. 249**
 * Neuron Structure

2. Insert an image of a neuron with a myelin sheath.**
 * Myelin Sheath

Myelin sheaths are for protecting axons. Myelin is a lipid substance. it also plays a big role in nerve regeneration. It creates a passage way for new fiber growth.
 * 3. What is the myelin sheath made of? Where is it located? What is its function? p. 249**

The CNS is gray matter because it contains no myelinated axons; white matter is white because it does. In PNS, the myelin gives nerve fibers their white, glistening appearance. serves as an insulator.
 * 4. What is the difference between the "gray matter" and "white matter" in the brain? p.249**

Caused by a loss of myelin from the axons. MS is believe to be caused by the bodys immune system attacking the myelin.
 * 5. What causes multiple sclerosis? P.249**

5. Where are the sodium and potassium ions when the axon is at rest? What is the charge inside the axon?** when resting the axon is not conducting an impulse. the concentration of sodium ions is outside the axon. potassium is inside.
 * Nerve Impulse p.250-252

it is only permeable to K (potassium) and because of this the outside charge is more positive.
 * 6. Which ions can cross the membrane and enter the axon? potassium or sodium?**

When they open the charge on the inside becomes positive. (depolarization)
 * 7. What happens to the charge inside the axon when sodium gates open? Where does sodium go?**

It changes back to negative. It just exits axon. (repolarization)
 * 8. What happens to the charge inside the axon when the potassium gates open? Where does potassium go?**

Depolaization is the positive charge increasing
 * 9. Look at the graph on page 251. What do you think depolarization means? What do you think repolarization means?**


 * 10. What causes depolarization of the axon?**


 * 11. What causes repolarization of the axon?**


 * 12. What is an action potential?**


 * 13. How does the sodium potassium pump reestablish the resting potential during the refractory period?**


 * 14. What is a synapse?**


 * 15. What is a synaptic cleft?**


 * 16. What is a neurotransmitter?**


 * 17. Since neuron's don't touch, how is the signal from one neuron transmitted to another neuron?**


 * 18. Insert an image showing an action potential.**


 * 19. Insert an image showing a synapse. **