Describe the difference between myelinated and unmyelinated nerve fibers (Be Specific). Why is the speed of signal conduction faster in myelinated fibers?

Figure 35.11 Potassium channel blockers, such as amiodarone and procainamide, which are used to treat abnormal electrical activity in the heart, called cardiac dysrhythmia, impede the movement of K+ through voltage-gated K+ channels. Which part of the action potential would you expect potassium channels to affect?

Which of the following statements best describes saltatory conduction? a. It inhibits direct neurotransmitter release. b. It transmits the action potential at the nodes of Ranvier andthus speeds up impulses on myelinated axons. c. It increases neurotransmitter release at the presynapticmembrane. d. It decreases neurotransmitter uptake at chemically gatedpostsynaptic channels. e. It removes neurotransmitters from the synaptic cleft.

Discuss the function of each of the following: astrocytes, oligodendrocytes, ependymal cells, in icroglia, cranium, vertebral column, meninges, cerebrospinal fluid, and blood—brain barrier.

Which of the following does not contribute to propagation of action potentials? a. As the area outside the membrane becomes negative, itattracts ions from adjacent regions; as the inside of the membrane becomes positive, it attracts negative ions from nearby in the cytoplasm. These events depolarize nearby regions of the axon membrane. b. The refractory period allows the impulse to travel in only one direction. c. Each segment of the axon prevents the adjacent segments from firing. d. The magnitude of the action potential stays the same as it travels down the axon. e. Up to a limit, increasing the intensity of the stimulus increases the number of action potentials.

In the propagation of a nerve impulse: a. the refractory period begins as the K+ channel opens, allowing K+ ions to flow outward along their concentrationgradient. b. Na+ ions flow out of the axon with their concentration gradient. c. positive charges lower the membrane potential to its lowestaction potential. d. gated K+ channels open at the same time as the activationgate of Na+ channels closes. e. the depolarizing stimulus lowers the membrane potential toopen the Na+ gates.

Watch this video (http://openstaxcollege.org/l/motorpathway) to learn more about the descending motor pathway for the somatic nervous system. The autonomic connections are mentioned, which are covered in another chapter. From this brief video, only some of the descending motor pathway of the somatic nervous system is described. Which division of the pathway is described and which division is left out?

If a person has a motor disorder and cannot move their aim voluntarily, but their muscles have tone, which motor neuron—upper or lower—is probably affected? Explain why.

Why do neurotransmitters have to be removed from the synapse?

A presynaptic neuron in the cerebrum transmits information to hundreds of other neurons. This process is an example of (a) convergence (b) divergence (c) temporal summation (d) spatial summation (e) a graded potential