1. Nervous Tissue

2. The Neuron
A neuron is a type of cell type that conducts impulses, or action potentials.
The structural components of a neuron are:
1. cell body - the large area filled with cytoplasm and containing a nucleus.
2. dendrites – the many projections from the cell body.
3. hillock – the cone-shaped projection that extends from the cell body and becomes the axon (nerve fiber).

3. The Neuron
4. Schwann cells- neuroglia cells that cover and wrap around the axon of peripheral nerves.
5. myelin – a fatty white substance found in the Schwann cell.
6. nodes of Ranvier – the gaps that occur between the
Schwann cells.
7. telodendria – the distal ends of axons they are usually branched.
The telodendria are sometimes referred to as:
Axon terminals
Synaptic knobs

4. Neuron

5. Schwann Cell vs Myelin

6. Dendrite
Cell Body
Nucleus
Axon Hillock
Axon

7. Axon Terminal or Synaptic knobs
Cell Body
Nucleus
Schwann Cell
Myelin
Axon
Node of Ranvier
Telodendria
Axon Terminal or Synaptic knobs

8. The Shapes of Neurons (3)

9. Unipolar Neuron
Associated with “touch”
Cell Body
Dendrite
Axon
CNS
Have one extension from the cell body that splits to become two long branches.
Carry impulses towards the central nervous system.

10. Bipolar Neuron Has two projections from the cell body.
Associated with sight, smell and hearing
Dendrite
Axon
Cell Body
Has two projections from the cell body.
One process conducts impulses towards the cell body and the other process conducts impulses away from the cell body.

11. Multipolar Neuron Has multiple projections from the cell body.
Associated with skeletal muscles
Cell Body
Axon
Dendrites
Has multiple projections from the cell body.
Most common type of neuron.

12. Sensory Neurons Afferent = Toward the CNS
These carry sensory information from the body to the CNS (brain and spinal cord)
Two subdivisions:
1. Somatic fibers – relay information from the skin, skeletal muscles and joints.
2. Visceral fibers – relay information from internal body organs.

13. Motor Neurons Efferent = Away from CNS
These are neurons that carry information from CNS to the body, specifically, to the:
Muscles
Glands

14. “Gray” Matter
Brain tissue is made up of millions of neurons.
It is gray because there is no myelin protecting the axons

15. Glial Cells (helper cells)
4 different types of glial cells
Associated with neurons
Provide supportive to neurons
AKA: neuroglia

16. Supporting Cells in the CNS Astrocytes
Star Shaped
Many functions
Monitor the exchanges between capillaries and neurons
Nutrient transfer

17. Supporting Cells in the CNS Oligodendrocytes
Produce the myelin sheath which provides insulation for some neurons in the CNS
They do the same thing as the Schwann cells, just at a different location

18. Supporting Cells in the CNS Microglia
Small oval cells with long thorny processes
Monitor the health of neurons
Specialized immune cells that phagocytize microorganisms and debris