Transcript PowerPoint to accompany Hole’s Human Anatomy and

10.1: Introduction
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Dendrites
• Cell types in neural tissue:
• Neurons
• Neuroglial cells (also
known as neuroglia, glia,
and glial)
Cell body
Nuclei of
neuroglia
Axon
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© Ed Reschke
Divisions of the
Nervous System
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Brain
• Central Nervous System (CNS)
• Brain
• Spinal cord
Cranial
nerves
Spinal
cord
• Peripheral Nervous System (PNS)
• Cranial nerves
• Spinal nerves
Spinal
nerves
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(a)
Divisions of Peripheral
Nervous System
• Sensory Division
• Picks up sensory information and delivers it to the CNS
• Motor Division
• Carries information to muscles and glands
• Divisions of the Motor Division:
• Somatic – carries information to skeletal muscle
• Autonomic – carries information to smooth muscle,
cardiac muscle, and glands
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Divisions Nervous System
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Central Nervous System
(brain and spinal cord)
Brain
Peripheral Nervous System
(cranial and spinal nerves)
Cranial
nerves
Sensory division
Spinal
cord
Sensory receptors
Spinal
nerves
Motor division
Somatic
Nervous
System
Skeletal muscle
Autonomic
Nervous
System
Smooth muscle
Cardiac muscle
Glands
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(a)
(b)
Functions of Nervous System
• Sensory Function (receiving • Integrative Function (deciding
information)
what to do about information)
• Sensory receptors gather
• Sensory information used to
information
create:
• Sensations
• Information is carried to the
• Memory
CNS
• Motor Function (acting
on information)
• Decisions are acted
upon
• Impulses are carried
to effectors
• Thoughts
• Decisions
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10.3: Description of Cells of
the Nervous System
• Neurons vary in size and shape
• They may differ in length and size of their axons and
dendrites
• Neurons share certain features:
• Dendrites
• A cell body
• An axon
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Neuron Structure
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Chromatophilic
substance
(Nissl bodies)
Dendrites
Cell body
Nucleus
Nucleolus
Neurofibrils
Axonal
hillock
Impulse
Axon
Synaptic knob of
axon terminal
Nodes of Ranvier
Myelin (cut)
Axon
Nucleus of
Schwann cell
Schwann
cell
Portion of a
collateral
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10.4: Classification of Neurons
and Neuroglia
• Neurons vary in function
• They can be sensory, motor, or integrative neurons
• Neurons vary in size and shape, and in the number of axons
and dendrites that they may have
• Due to structural differences, neurons can be classified into
three (3) major groups:
• Bipolar neurons
• Unipolar neurons
• Multipolar neurons
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Classification of Neurons:
Structural Differences
• Multipolar neurons
• 99% of neurons
• Many processes
• Most neurons of
CNS
• Bipolar neurons
• Two processes
• Eyes, ears, nose
• Unipolar neurons
• One process
• Ganglia of PNS
• Sensory
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Dendrites
Peripheral
process
Axon
Direction
of impulse
Central
process
Axon
Axon
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(a) Multipolar
(b) Bipolar
(c) Unipolar
Classification of Neurons:
Functional Differences
• Sensory Neurons
• Afferent (approach)
• Carry impulse to CNS
• Most are unipolar
• Some are bipolar
• Interneurons
• Link neurons in CNS
• Aka association neurons
• Multipolar
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Central nervous system
Peripheral nervous system
Cell body
Dendrites
Sensory
receptor
Cell body
Axon
(central process)
Axon
(peripheral process)
Sensory (afferent) neuron
Interneurons
• Motor Neurons
• Efferent (exit)
• Carry impulses away from CNS
to effectors
• Multipolar
Motor (efferent) neuron
Axon
Effector
(muscle or gland)
Axon
Axon
terminal
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Types of Neuroglial Cells
in the PNS
1) Schwann Cells
• Produce myelin found on peripheral myelinated neurons
• Speed up neurotransmission
2) Satellite Cells
• Support clusters of neuron cell bodies (ganglia)
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Types of Neuroglial Cells
in the CNS
1) Microglia
• CNS
• Phagocytic cell
3) Oligodendrocytes
• CNS
• Myelinating cell
4) Ependyma or ependymal
2) Astrocytes
• CNS
• CNS
• Ciliated
• Scar tissue
• Line central canal of spinal
• Mop up excess ions, etc.
cord
• Induce synapse formation
• Line ventricles of brain
• Connect neurons to blood
• Keep CSF moving
vessels
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Types of Neuroglial Cells
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Fluid-filled cavity
of the brain or
spinal cord
Neuron
Ependymal
cell
Oligodendrocyte
Astrocyte
Microglial cell
Axon
Myelin
sheath (cut)
Capillary
Node of
Ranvier
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10.5: The Synapse
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• Nerve impulses pass
from neuron to neuron at
synapses, moving from a
pre-synaptic neuron to a
post-synaptic neuron.
Synaptic
cleft
Impulse
Dendrites
Axon of
presynaptic
neuron
Axon of
postsynaptic
neuron
Axon of
presynaptic
neuron
Impulse
Cell body of
postsynaptic
neuron
Impulse
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Synaptic Transmission
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Direction of
nerve impulse
• Neurotransmitters are
released when impulse
reaches synaptic knob
Axon
Ca+2
Synaptic knob
Synaptic
vesicles
Presynaptic neuron
Ca+2
Cell body or dendrite
of postsynaptic neuron
Mitochondrion
Ca+2
Synaptic
vesicle
Vesicle releasing
neurotransmitter
Axon
membrane
Neurotransmitter
Synaptic cleft
Polarized
membrane
Depolarized
membrane
(a)
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