NERVOUS SYSTEM
FUNCTION
 Directs:
 Links:
DIVISIONS OF THE NERVOUS SYSTEM
Both of the systems listed below work together to maintain homeostasis in the body.
 Central Nervous System (CNS) –
 Composed of:
 Controls:
 Integrates:
 Dependent upon:
 Peripheral Nervous System (PNS)
 Communication link:
 Contains:
 Composed of:
 Divisions of PNS

Somatic Nervous System (Voluntary)

Autonomic Nervous System (ANS)

Sympathetic N.S. –

Parasympathetic N.S. –
NERVOUS SYSTEM CELL TYPES
NEURONS –
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NEUROGLIA (GLIAL CELLS) –






 There are four types of glial cell types (neuroglia) in the CNS:

Astrocytes –

Oligodendrocytes –

Ependymal Cells –

Microglia –
 There are two types of glial cell types (neuroglia) in the PNS:

Schwann Cells –

Satellite Cells –
NEURON STRUCTURE
 Cell Body (perikaryon or soma) –

Nissl bodies –
2

Cytoplasm –
 Neuron Processes (Neurites)

Two types of neuron processes:
 Dendrites –
 Axon (nerve fiber) –

Axoplasm –

Axolemma –

Axon hillock –

Axon collaterals –

Telodendria –

Synaptic knobs (terminal boutons) –

Schwann cell –

Myelin sheath –

Node of Ranvier –

Neurilemma –
CLASSIFICATION OF NEURONS
 Structural Classification

Multipolar –

Bipolar –

Unipolar –
3
 Functional Classification

Afferent (sensory) –

Efferent (motor) –

Association neurons or interneurons –
OTHER NERVOUS SYSTEM STRUCTURES
 Ganglion –
 Nuclei –
 Tract –
 Nerve –


Composed of many bundles of axons called fascicles

Each nerve is enclosed by connective tissue coverings:

Endoneurium –

Perineurium –

Epineuriun –
NEURON FUNCTION
THE SYNAPSE –
 Two types:

Electrical synapses –

Chemical synapses –
4
 Neurotransmitters –

Released at:

Produced in:

Stored in:

Release caused by:
THE RESTING MEMBRANE POTENTIAL
 Resting Membrane Potential (RMP) –

Excitatory neurotransmitters –
 Depolarization –

Inhibitory neurotransmitters –
 Hyperpolarization –
MEMBRANE POTENTIALS ACTING AS SIGNALS
 Graded Potentials




5
POSTSYNAPTIC POTENTIALS
 Excitatory Postsynaptic Potentials (EPSP) –
 Inhibitory Postsynaptic Potentials (IPSP) –
TYPES OF NEUROTRANSMITTERS
 There are over 40 known neurotransmitter substances. Some of the most common are:

Acetylcholine (Ach) –

Norepinephrine –

GABA (Gamma aminobutyric acid) –

Dopamine –

Serotonin –
THE ACTION POTENTIAL (NERVE IMPULSE)
 Consists of:



 If depolarization reaches threshold:
 The positive RMP change causes:
 A sudden influx of:
 Begins at:
 Types of Ion Channels

Chemically Gated –
6

Voltage Gated –
 Propagation –
 Repolarization –
 Sodium-Potassium Pump –
 Absolute Refractory Period –
 Summation –

Spatial summation –

Temporal summation –
 All-or-None Phenomenon



 Saltatory Conduction –
SUMMARY OF EVENTS
7
CLASSIFICATION OF NERVE FIBERS
 Nerve fibers may be classified based on their diameter, degree of myelination, and speed of conduction.


 Fiber Types

Type A Fibers –

Type B Fibers –

Type C Fibers –
TYPES OF NEURONAL CIRCUITS
 Converging circuits –
Convergence
 Diverging Circuits –
RECEPTION, TRANSMISSION AND RESPONSE
Divergence
 Reflex Action –
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