2. Nervous System
– Central nervous system (CNS):
• Brain
• Spinal cord
– Peripheral nervous system (PNS):
• Sensory neurons
• Motor neurons (somatic and
autonomic)
5. The Nervous System
• A physical organ system like any other
• 2 main kinds of cells
– Neurons
– Glia
6. Basic units of the nervous system
Receive, integrate, and transmit
information
Operate through electrical impulses
Communicate with other neurons
through chemical signals
More about neurons and neuronal
anatomy later
Neurons
7. Glial cells
• 100 billion neurons
• 10x more glial cells
• Glial cells
– Support neurons (literally, provide physical
support, as well as nutrients)
– Cover neurons with myelin
– Clean up debris
– “Housewives”
9. Three main types of neurons
• Sensory Neurons
• Interneurons
• Motor Neurons
10. Sensory (Afferent) vs. Motor (Efferent)Sensory (Afferent) vs. Motor (Efferent)
e.g., skin
e.g., muscle
Gray’s Anatomy 38 1999
sensory (afferent) nerve
motor (efferent) nerve
Neurons that send signals from the senses,
skin, muscles, and internal organs to the CNS
Neurons that transmit commands from the
CNS to the muscles, glands, and organs
13. Neurons
Axon of another
neuron
Axon of another
neuron
Cell BodyCell BodyDendritesDendrites
AxonAxon
Myelin
Sheath
Myelin
Sheath
Dendrites of
another neuron
Dendrites of
another neuron
14. Neural Anatomy
Dendrite
the bushy, branching extensions of a
neuron that receive messages and
conduct impulses toward the cell body
Axon
the extension of a neuron, ending in
branching terminal fibers, through which
messages are sent to other neurons or to
muscles or glands
15. Neural Anatomy and
communication
Synapse
junction between the axon tip of the sending
neuron and the dendrite or cell body of the
receiving neuron
tiny gap at this junction is called the synaptic
gap or cleft
Synapse movie
17. Specific Parts: The Neuron
Function
Neurons = 3 functions: Reception, Conduction, Transmission
1.3.
2.
18. Action Potential
When dendrites stimulated, the delicate
balance is altered
Membrane breaks down
Positively charged ions rush in
(depolarization)
Charge = less negative
Causes release of chemicals from
terminal buttons
20. Relay Race
• Action Potential starts at dendrite
– Through cell body
– Down Axon
– Axon Terminals
• How does it get to the next cell’s dendrites?
• Neurons don’t touch
– Synapse = millionth inch gap
– In synapse = vesicles w/ neurotransmitters
» Chemical messengers that transmit info
22. Myelin Sheath
–Fatty material made by glial cells
–Insulates the axon
–Allows for rapid movement of
electrical impulses along axon
–Nodes of Ranvier: gaps in myelin sheath
where action potentials are transmitted
–Multiple sclerosis is a breakdown of
myelin sheath
–Speed of neural impulse Ranges from 2 –
200+ mph
24. Neurotransmitters
chemical messengers that traverse the
synaptic gaps between neurons
when released by the sending neuron,
neurotransmitters travel across the
synapse and bind to receptor sites on
the receiving neuron, thereby
influencing whether it will generate a
neural impulse
25. Neurotransmitters (>60)
• Acetylcholine (ACh)
– 1st
substance identified as NT
– Links motor neurons and muscles (contract or relax)
• e.g. curare vs black widow spider
– Also involved in memory, learning, sleep, dreaming
(acetylcholine movie)
• Endorphins (the brain’s own morphine)
– 1973 injected rats with morphine
– Bound like NTs
– Brain had receptors for exogenous substance?
• Brain must produce its own morphine
• Released during pain and discomfort
Figure 3.20 on page 89
The sympathetic division of the nervous system prepares the body for action, whereas the parasympathetic returns it to a resting state.
Figure 2.5B from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Figure 2.6 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:
Figure 2.6 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source:
Figure 2.7 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
Source: