1. In the 1800s, the scientist Paul Ehrlich injected blue dye into the bloodstream of animals. He observed that all tissues except the CNS/brain turned blue. Based on what you know about the CNS, explain Ehrlich’s results. What experiment could you design in order to stain the brain a blue color?

2. The pyrethrin insecticides disable inactivation gates of Na+ channels so that the channels remain open. In neurons poisoned with pyrethrins, what would you predict would happen to the membrane potential? Explain your answer.

3. Hyperkalemia is an excess of potassium in the extracellular fluid. What effect would this have on the resting membrane potentials of the nervous system and on neuronal excitability?

4. During sleep, relay neurons in the thalamus reduce information reaching the cerebrum by altering their membrane potential. Are these neurons more likely to have depolarized or hyperpolarized? Explain you reasoning.

5. What would happen if the dorsal root of a spinal nerve were damaged (be specific)?

6. If the Na+ – K+ pumps of nerve cells slowed down due to a metabolic disorder, how would this affect the resting membrane potential? Would it make neurons more excitable or more difficult to stimulate?

7. A person can survive destruction of an entire cerebral hemisphere but cannot survive destruction of the hypothalamus, which is a much smaller mass of brain tissue. Explain this difference and describe some ways that destruction of a cerebral hemisphere would affect one’s quality of life

8. Novocain is a local anesthetic that prevents voltage-gated Na+ gates from opening. Explain why this would block the conduction of pain signals in a sensory nerve.

9. Organize the following terms into a map or outline: somatic, afferent, peripheral nervous system, spinal cord, sensory, sympathetic nervous system, autonomic, brain, parasympathetic nervous system, efferent, motor, central nervous system.

10. Draw 3 neurons that synapse with one another (include one excitatory neuron and one inhibitory neuron). Label the presynaptic and postsynaptic neuron(s), cell bodies, dendrites, axons and axon terminals. Draw an arrow(s) to the location of all the voltage-gated channels and ligand-gated channels we discussed. Draw an arrow(s) to the location(s) of action potential propagation and graded potentials.

11. In diagnosing bacterial and viral infections of the nervous system, samples of CSF are extracted from the spinal cord. Specifically where would the CSF be extracted from and what meningeal layers and spaces would the needle pass through starting with the most superficial layer/space.

12. If a cell experienced a large increase in the concentration of Cl- ions in the ICF, would the membrane potential be higher or lower than the resting membrane potential? Why?