1. The Nervous System
Nerve Cells

2. Nerve Cells
Called “neurons”
Three Types
Motor
Sensory
Inter

3. Motor Neurons
Relays messages from brain or spinal cord to muscles and organs

4. Sensory Neurons
Relays message from receptors (like in skin) to brain or spinal cord

5. Interneurons Makes up the brain and spinal cord
Relays messages from sensory to motor neurons

6. Parts of a Nerve Cell Cell body Nucleus Dendrites Axon Terminal Fibers
Synaptic Endings
Myelin Sheath

7. Cell Body The largest part of the cell.
It holds the general parts of the cell like the nucleus and other organelles needed for the cell to function

8. Nucleus
Control Center of the cell
Contains most of the cell’s DNA

9. Dendrites Large, branching area near cell body
Brings information TO cell body
Rough Surface
Usually many per cell

10. Axon Branch further from cell body
Carries information AWAY from cell body
Usually only one per cell
Smooth Surface

11. Terminal Fibers Branches of an axon Have synaptic endings which send
neurotransmitters from
one cell to another

12. Myelin Sheath Insulating fat layer surrounding the
axon of a nerve cell.
Helps messages travel
Faster and stops them
From leaking away

13. What is a Nerve?
A nerve is a discrete bundle of several thousand neuron axons wrapped around each other

14. How Do Nerves Transmit Messages?

15. Answer:
Chemicals (transmitting molecules), called neurotransmitters, are sent from axon terminal across synapse (synaptic cleft) to a receptor on a dendrite.