CHAPTER 2: NERVE CELLS & NERVE IMPULSES
Part I: Nerve Cells and Nerve Impulses
Terms:
Neuron Lysosomes
Glia Golgi Complex
Soma (Cell Body) Sensory Neuron
Dendrites Motor Neuron
Dendritic Spines Interneurons
Synapses Afferent Axon
Presynaptic Terminals (End bulbs) Efferent Axon
Myelin Sheath Intrinsic Axon
Cell Membrane Astrocytes
Cytoplasm Oligodendrocytes
Cell Nucleus Schwann Cells
DNA Radial Cells
Chromosones Plasticity
Mitochondria Blood-Brain Barrier
Ribosomes Active Transport System
Endoplasmic Reticulum
Concepts/Questions:
1. What are the two general types of cells in the nervous system?
2. What name the typical parts of a neuron (its structure).
3. Be able to label the individual structures in the a typical human neuron. What are the functions of
each of these neuronal structures?
4. Describe the locations, typical numbers of, and functions of dendrites and axon terminals,
respectively. Why does the added surface area provided by dendritic spines aid in neural
communication?
5. What are the functions/characteristics of Sensory, Motor, Intrinsic and Inter-neurons? Which are the
most frequently found neuron in the nervous system (particularly within the brain).
6. Distinguish among afferent and efferent axons. Give an example of each.
7. List the different types of glia mentioned in class. What is the function of each type? Is the fewer or
greater glia than neurons in the body? Generally speaking, do glia or neurons occupy more total
mass of the body?
8. As we age in life, describe the potential changes in the brain's neural structure (think neural death
and neural growth). How does this question relate to the concept of plasticity?
9. What is generally the process of brain cancer growth? Why don’t most cancer fighting drugs attack
cancer in the central nervous system?
10. Why is the Blood-Brain Barrier important to have for the brain, but would be unhelpful if the rest of the
body's circulation was "barrier-ed"? What mechanism assures that the brain is not completely cut off
from nutrients. What are some substances that can cross the BBB, and why is this possible?
Part II: The Nerve Impulse
Terms:
Resting Potential (Axon-located) Local Anesthetic
Polarization General Anesthetic
Bi-Lipid Layer Absolute Refractory Period
Selective Permeability Relative Refractory Period
Concentration Gradient Axon Hillock
Sodium Ions (Na+) Propogation
Potassium Ions (K+) Unmyelinated Axons
Chloride Ions (Cl-) Myelinated Axons
Microelectrode Nodes of Ranvier
Electrical Gradient Saltatory Conduction
The Action Potential Local Neurons
Hyperpolarization Graded Potentials
Depolarization
Threshold
Action Potential
All-or-None Law
Voltage Activated Channels
Questions/Concepts:
1. What is the resting potential (generally speaking and specifically in terms of millivolts). How is it
measured?
2. What are the two types of pressure gradients that affect ionic movement and are responsible for the
existence of a resting potential. Explain each.
3. Name the factors that are responsible for concentration gradients in the neuron. How is this related
to Sodium and Potassium Ions?
4. How do selective permeability and the sodium-potassium pump lead to an electric gradient
(electrostatic pressure)?
5. Why is the resting potential of behavioral/evolutionary importance?
6. How is a suprathreshold stimulation of a nerve like flushing the toilet?
7. Name the 6 steps sequence of ionic movement during the action potential and relate these changes
to changes in the electrical potential (difference in electrical signal between inside and outside of the
cell).
8. How do local and anesthetic acts to dull pain?
9. Shortly after the nerve "fires" (the action potential), and the electrical potential of the cell is still above
its threshold, why don't the voltage channels re-open allowing the cell to fire again? What would it
nd
take to get the cell to produce a 2 AP shortly after a first?
10. How does the action potential "propagate" from one location to the next locations, thus produce a
"forward wave of depolarization" down the length of the axon? Why is must this be a "forward
wave"?
11. What is an average speed of conduction for a myelinated axon? How does this speed compare to
unmyelinated axon?
12. Relate the concept of "graded potentials" to electrical propagation in dendrites and cell bodies and
local neuron (Discuss specifically what happens to the electrical wave if the graded potentials are
weak or strong?).