1. Introduction to the Nervous System Ms. Cohen
Of all the Nerve!
Introduction to the Nervous System
Ms. Cohen

2. Organs of the Nervous System
Brain
Spinal cord
Numerous nerves
Specialized sense organs such as eyes and ears
Microscopic sense organs such as those found in the skin

3. Divisions of Nervous System
Central Nervous System
Peripheral Nervous System
CNS - Brain, spinal cord
PNS - Nerves that extend to the periphery of body
Autonomic nervous system - involuntary functions (breathing rates, respiratory rates, etc)
Somatic - voluntary functions (motor neurons)

4. Cool link to understanding the divisions of the Nervous System

5. Neurons What do they do? 3 parts:
carry the impulses that make things happen.
cell body, branching projections called dendrites and elongated axons.

6. Supporting cells
Glial cells (astrocytes): Specialized connective tissue cells that support & protect neurons
Microglia - smaller, microbe eating scavengers
Oligodendrocytes -help to hold nerve fibers together and produce myelin

7. Sensory neurons transmit impulses to the spinal cord and brain from all parts of the body.
Motor neurons transmit impulses in the opposite direction - away from the brain and spinal cord.
Interneurons conduct impulses from sensory neurons to motor neurons.
Conduct impulses
From sensory to
Motor neurons
To spinal cord
Away from spinal cord

8. Axon is covered in ________________.
Myelin is formed by ____________ __________.
Nodes of Ranvier -
Myelin
Schwann cells
are indentations between adjacent Schwann cells that aid in quick transmission of signals

10. Nerve Bundle Organization
White matter - has myelin
Each axon in a nerve is surrounded by fibrous connective tissue called endoneurium.
Groups of these axons are called fascicles which are surrounded by perineurium
Epineurium covers whole nerve (fibrous sheath)

11. Reflex Arcs - no brain involvement

12. Nerve Impulses Self propagating wave of electrical disturbance that
travels along the surface of a neuron’s plasma membrane.
Stimulus occurs
Charges across the membrane change from - to +
This change “travels” down the membrane of axon
Synapse occurs at terminal end of presynaptic neuron
Post synaptic neuron receives impulse and carries
on the “message” or signal

13. Action Potential

15. Action Potential Video