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Copyright © 2010 Pearson Education, Inc.
Nervous System
Copyright © 2010 Pearson Education, Inc.
Figure 8-1
Copyright © 2010 Pearson Education, Inc.
8-2: Neurons & NeurogliaI. Neurons - send & receive signals
A. Structure• Cell body (soma) – contains organelles• Dendrites – receive info• Axon – carries outgoing signals• Synaptic terminals – ends of axons
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8-2: Neurons & Neuroglia
B. Organization
– clusters of cell bodies form gray
matter
• In PNS ganglia
• In CNS centers or nuclei,
cortex
– bundles of axons form white
matter
• In PNS nerves
• In CNS tracts or columns
Copyright © 2010 Pearson Education, Inc.
8-2: Neurons & Neuroglia
II. Neuroglia (glial cells)
A. Neuroglia in CNS:
1. Astrocytes: support & repair
– maintain blood-brain barrier
2. Oligodendrocytes: form myelin around axons
3. Microglia: phagocytic cells (protection)
4. Ependymal cells: produce or circulate cerebrospinal
fluid (CSF)
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8-2: Neurons & Neuroglia
B. Neuroglia in PNS
1. Satellite cells: support neurons
2. Schwann cells: form myelin
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Quiz Thursday
• Structure of a neuron
• Neuroglia in CNS & PNS
• Information processing throughout the CNS & PNS
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8-3: Membrane & Action Potential
I. Membrane Potential – charge difference on either side of PM
A. Contributing Factors:• Ions (Na+, K+,Cl-) &
proteins (Pr-) • Membrane Channels
– Leak channels
– Gated channels
– Na+ / K+ exchange pump
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8-3: Membrane & Action PotentialB. Resting Potential of neuron is
-70mV
C. Graded Potential : localized Δ in resting potential
• depolarization: shift toward 0mV
D. Action Potential: electrical
impulse affecting entire PM
• occurs when stimulus
causes depolarization to
threshold (-60mV)
• All-or-none principle
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8-4: Synapses
• Synapse – site where a neuron communicates w/ another cell
• Presynaptic neuron transmits AP to postsynaptic neuron or
effector cell via neurotransmitters
– can be excitatory or inhibitory
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Synapses
• Types of NTs:
– Norepinephrine – released at adrenergic synapses -
excitatory
– Dopamine, serotonin, GABA – inhibitory
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8-5: The Meninges
• Meninges – protect brain & spinal cord (3 layers)
– contains CSF
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8-7: The Brain
• CSF - produced at choroid plexus (capillary network)
lined by ependymal cells
– transports chemical messengers, nutrients, wastes
– cushion & support
– Ventricles: 4 chambers each w/ a choroid plexus
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Major Regions of the Brain
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8-6: Anatomy of Spinal Cord
• Central canal: filled w/
CSF
• Dorsal root: sensory
neurons
• Ventral root: motor
neurons
• Dorsal & ventral roots join
to form a spinal nerve
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I. CerebrumA. Corpus callosumB. Primary sensory cortexC. Association areas
– Premotor cortexD. General interpretive area (Wernicke area)E. Prefrontal cortexF. Basal nucleiG. Limbic system
– Amygdala – Hippocampus
II. DiencephalonA. EpithalamusB. ThalamusC. Hypothalamus
III. CerebellumIV. Brain Stem
A. Midbrain– Reticular formation
B. PonsC. Medulla oblongata
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The Brain
Figure 8-16a
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The Brain
Figure 8-16b
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The Brain
Figure 8-16c
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The Cerebrum
Figure 8-19
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8-9: Reflexes
• Reflex: automatic response to stimulus
– Reflex arc: opposes original stimulus (fig 8-28)
1. Stimulus activates receptor
2. Activation of sensory neuron
3. Integration by postsynaptic cell
4. Activation of motor neuron
5. Effector response
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Figure 8-28
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8-9: Reflexes
– Monosynaptic reflex: sensory neuron synapses directly
on motor neuron
• stretch reflex
– Withdrawal Reflex: move body part away from stimulus
• flexor reflex
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Stretch Reflex
Figure 8-29
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A Flexor Reflex
Figure 8-30
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Aging and the Nervous System
• Anatomical and physiological changes begin after
maturity (age 30)
• 85% of people over age 65 have changes in mental
performance and CNS function
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Aging and the Nervous System
• Reduction in Brain Size and Weight
• Reduction in Number of Neurons
• Decrease in Blood Flow to Brain
• Changes in Synaptic Organization of Brain
• Changes in CNS Neurons
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