cells of the nervous system
1. Neurons
Functional units of the nervous system Three specialized nerve cells groups:
- Sensory neurons
- Interneurons
- Motor neurons
Components: Dendrites, Cell Bodies, and Axons
Myelin Sheath
Whitish coat of a fatty protein, segmented around most axons.
It functions to:
Factors increasing the speed of movement of the nerve impulse:
Whitish coat of a fatty protein, segmented around most axons.
It functions to:
- Protect the axon
- Electrically insulate fibers
- Increase the speed of nerve impulse transmission
Factors increasing the speed of movement of the nerve impulse:
- Myelinated axons compared to non-myelinated axons
- Size of diameter of axon ( increase diameter = decrease speed of nerve impulse)
- Nerve impulses jumping from Node of Ranvier to another
2. Glial Cells
Schwann Cells in PNS and Oligodendrocytes in CNS produce the myelin shealth on neurons.
- Also known as Neuroglial cells or Supporting Cells
- Non-conducting cells
- Structural Support
- Health and growth of nerve cells
Schwann Cells in PNS and Oligodendrocytes in CNS produce the myelin shealth on neurons.
NERVE REPAIR
Neurilemma
White Matter
Grey Matter
Does not regenerate after injury = Permanent damage!
- Thin membrane surrounding axon
- On all nerve fibres in the PNS
- Promotes regeneration of damaged axons.
White Matter
- Nerves within brain and spinal cord (CNS)
- Myelinated fibres
- Has Neurilemma
Grey Matter
- Other nerves in brain and spinal cord (CNS)
- Non-myelinated fibres
- No Neurilemma
Does not regenerate after injury = Permanent damage!
Now that we have an understanding of the structure of the axon, let's investigate how a nerve impulse or action potential is created.
Resources:
DiGiuseppe, Maurice et al. (2003). Nelson Biology 12. Nelson Canada ELHI (1 Edition). Toronto, Ontario: Thomson Canada Limited
DiGiuseppe, Maurice et al. (2003). Nelson Biology 12. Nelson Canada ELHI (1 Edition). Toronto, Ontario: Thomson Canada Limited