1. Chapter 1 Nerve Cells and Nerve Impulses

2. The Structure of a Neuron
Neuron cells are similar to other cells of the body but have a distinctive shape
Figure 1.3 Neurons, stained to appear dark
Note the small fuzzy-looking spines on the dendrites.
Photo courtesy of Bob Jacobs, Colorado College

3. Nervous System - brain - spinal cord neuron: - primary units of
the nervous
system
- nerve cell:
- cell body
- dendrites
axons
2008 McGraw-Hill Co., Inc. All rights reserved

4. A Vertebrate Motor Neuron
Figure 1.4 The components of a vertebrate motor neuron
The cell body of a motor neuron is located in the spinal cord. The parts are not drawn to scale; a real axon is much longer in proportion to the soma.
© Cengage Learning

5. Dendrites
Branching fibers with a surface lined with synaptic receptors responsible for bringing information into the neuron
Some also contain dendritic spines that further branch out and increase the surface area of the dendrite
The greater the surface area of the dendrite, the more information it can receive

6. Dendritic Spines Figure 1.6 Dendritic spines
Many dendrites are lined with spines, short outgrowths that receive incoming information. Source: From K. M. Harris and J. K. Stevens, Society for Neuroscience, “Dendritic Spines of CA1 Pyramidal Cells in the Rat Hippocampus: Serial Electron Microscopy with Reference to Their Biophysical Characteristics.” Journal of Neuroscience, 9 (1989), pp. 2982–2997. Copyright © 1989 Society for Neuroscience. Reprinted by permission.

7. Cell Body/Soma Contains the nucleus, mitochondria, and ribosomes
Responsible for the metabolic work of the neuron
Covered with synapses on its surface in many neurons

8. Axons
Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs, or muscles
Maybe have a myelin sheath, an insulating material that contains interruptions in the sheath known as nodes of Ranvier
Presynaptic terminals at the end points of an axon release chemicals to communicate with other neurons

9. Afferent, Efferent, and Intrinsic
Afferent axon: refers to bringing information into a structure
Efferent axon: refers to carrying information away from a structure
Interneurons or intrinsic neurons are those whose dendrites and axons are completely contained within a single structure

10. Motor and Sensory Neurons
A motor neuron
Has its soma in the spinal cord
Receives excitation from other neurons
Conducts impulses along its axon to a muscle
A sensory neuron
Is specialized at one end to be highly sensitive to a particular type of stimulation (touch, light, sound, etc.)

11. Nervous System (cont.) Glial cells:
- support neurons and transport nutrients
- produce the myelin sheath
- influence the transmission of messages from
one neuron to another across synaptic
gaps
2008 McGraw-Hill Co., Inc. All rights reserved

12. Nervous System (cont.) Myelin sheath and synaptic transmission:
- white fatty coating on
axon
- multiple sclerosis
2008 McGraw-Hill Co., Inc. All rights reserved

13. The Blood-Brain Barrier
A mechanism that surrounds the brain and blocks most chemicals from entering
The immune system destroys damaged or infected cells throughout the body
Because neurons in the brain generally do not regenerate, it is vitally important for the blood brain barrier to block incoming viruses, bacteria, or other harmful material from entering

14. Blocking Sodium Channels
Local anesthetic drugs block sodium channels and therefore prevent action potentials from occurring
Example: Novocain and Xylocaine

15. Nervous System (cont.) Neural transmission: - ions - cell membrane:
- semi-permeable
- polarized
- depolarization
- action potential
- all-or-none principle
2008 McGraw-Hill Co., Inc. All rights reserved

17. The transmission of a nerve impulse.
The following are the answers to questions 1–4:
The answer is b. Outside.
The answer is a. Inside.
The answer is d. Negatively charged.
The answer is c. Positively charged.
The following is how the figure should be labeled:
b. Resting potential
a. Threshold
c. Depolarization
d. Repolarization
e. Hyperpolarization