3. a. If the membrane reaches the trigger point, known as
Threshold, what electrical potential will be generated?
b. During the depolarization phase, voltage-gated Na channels open and Na enters the cell. 4. What are the two processes that stop the potential from rising above +30 mV? a. Inactivation of voltage gated Na channels b. Opening of voltage gated K channels
5. a. The opening of voltage-gated K+ channels cause the membrane to repolarize. b. Does K+ move into or out of the cell? Out of c. If the membrane potential becomes more negative than –70 mV, this is called hyperpolarization. d. This potential is caused by what characteristic of K+ permeability? Slow decline
6. a. After an action potential, the neuron cannot generate another action potential because Na channels are inactived. This period is called the absolute refractory period. b. During the relative refractory period, the cell can generate another action potential but only if the membrane more depolarized. 7. a. Conduction velocity along the axon is increased by what two characteristics? 1. increased diameter 2. presence of myelin
b. Conduction along a myelinated axon is called saltatory conduction.
8. a. Name the disease whose symptoms include loss of vision and increasing muscle weakness: Multiple sclerosis (from the quiz section) b. What does this disease destroy? Myelin sheaths