copyright © 2010 pearson education, inc. nervous system

Copyright © 2010 Pearson Education, Inc.

Nervous System


Figure 8-1


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


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



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)



B. Neuroglia in PNS

1. Satellite cells: support neurons

2. Schwann cells: form myelin


Quiz Thursday

• Structure of a neuron

• Neuroglia in CNS & PNS

• Information processing throughout the CNS & PNS


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


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


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


Synapses

• Types of NTs:

– Norepinephrine – released at adrenergic synapses -

excitatory

– Dopamine, serotonin, GABA – inhibitory


8-5: The Meninges

• Meninges – protect brain & spinal cord (3 layers)

– contains CSF


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


Major Regions of the Brain


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


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


The Brain

Figure 8-16a


The Brain

Figure 8-16b


The Brain

Figure 8-16c


The Cerebrum

Figure 8-19


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


Figure 8-28


8-9: Reflexes

– Monosynaptic reflex: sensory neuron synapses directly

on motor neuron

• stretch reflex

– Withdrawal Reflex: move body part away from stimulus

• flexor reflex


Stretch Reflex

Figure 8-29


A Flexor Reflex

Figure 8-30


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


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

copyright © 2010 pearson education, inc. nervous system

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