1. NERVES

2. NERVES
a nerve is a
bundle of
neurons

3. Neuron Interaction & Integration
sensory neuron
sensory receptors
interneuron
effector
Interaction Between Neurons
motor neuron

4. Nerves 2 main types of nerve cells
Glial cells –non-conducting and used for structural and nutritional support
Neurons – carry nerve impulses

5. Typical Neuron
dendrite
cell body
Myelin sheath
Synapse
axon

7. Neuron Structure Functional cells of NS
Transmit electrochemical messages called nerve impulses to
Other neurons
Effectors (muscles or glands)

8. Neuron Structure (cont.)
Neurons lose their ability to divide
If destroyed, not replaced
Neuralgia
Support cells for neurons that can divide
Astrocytes – anchor blood vessels to nerves
Microglia – act as phagocytes
Oligodendrocytes – assist with production of myelin sheath

9. Neuron Structure (cont.)
Dendrites – short
Receive nerve impulses for the neuron
Axons – long
Send nerve impulses away from the cell body
Neurons have a cell body and processes called nerve fibers that extend from the cell body.

10. Neuron Structure (cont.)
White matter – axons with myelin sheath
Schwann cells
Wrap around some axons
Cell membranes contain myelin
Myelin insulates axons and enables axons to send nerve impulses more quickly
Gray matter – axons without myelin sheath
Schwann cells
Axon
Dendrites

11. Myelin Sheath
& Schwann Cell
Nodes of Ranvier

12. myelinated nerve fibers are covered by neurilemma which, along with the Schwann cell, promotes the regeneration of the nerve fiber after trauma

13. Components of a Neuron
Dendrites
are short branches that surround the cell body of the neuron.
Axons
carry impulses away from the cell body
Myelin sheath
Axons may be enclosed in a fatty sheath produced by a Schwann cell or glial cell. Acts as insulation for neurons by preventing the loss of charged ions. Very white in appearance.

14. Neurilemma
covers myelinated nerve fibers and it promotes the regeneration of the nerve fiber after trauma
Nodes of Ranvier.
small gaps between each Schwann cell on an axon
Saltatory Action
myelin sheath increases the speed of nerve transmission., from 1m/s to 100m/s or 360 Km/h

15. myelinated neurons form white matter in the unmyelinated grey matter
myelinated nerve fibers are
covered by neurilemma which
promotes the regeneration
of the nerve fiber after trauma
Unmyelinated nerves lack a
myelin sheath. These will not
be regenerated after injury.

16. Multiple Sclerosis Not hereditary. The cause of MS is not known.
T cells (immune cells) attack cells and tissues in the CNS. This results in damage to myelin, nerve fibers and the cells that make myelin. 

17. The main functions of the nervous system:
Receive information
Make decisions about the response
Sorts impulses and sets priorities for action
i.e. walking across the street – eat a bar or drive a car
Transmit impulses to the motor units (muscles) which carry out appropriate action