chapter 7 notes continued

Chapter 7 Nervous System

Part 4: Specialized cells

1.     Support cells = neuroglia

a.    Function –Support, insulate, and protect neurons.

b.    Types:

                                          i.    Astrocytes = star-shaped- brace neurons, abundant, form barrier between capillaries and neurons, control the chemical environment in the brain

                                        ii.    Microglia = small cells, spider-like phagocytes, dispose of debris.

                                       iii.    Ependymal cells-Line cavities of the brain and spinal cord, circulate cerebrospinal fluid with their cilia.

                                       iv.    Oligodendrocytes-Wrap around nerve fibers in the central nervous system, produce myelin sheaths.

                                         v.    Satellite cells- Protect neuron cell bodies

                                       vi.    Schwann cells- Form myelin sheath in the peripheral nervous system in a jelly roll-like fashion.

1.     Myelin sheath-Whiteish, fatty material covering axons

2.    Nodes of Ranvier- Gaps in myelin sheath along the axon; speeds up impulse.

2.    Nerve cells = neurons- Cells specialized to transmit messages.

a.    Cell body-Nucleus and metabolic center of the cell.

b.    Processes-Fibers that extend from the cell body.

                                          i.    Dendrites- Conduct impulses toward the cell body.

                                        ii.    Axons- Conduct impulses away from the cell body(longest cells in our bodies).

c.    Functional properties

                                          i.    Irritability

                                        ii.    Conductivity

                                       iii.    Nerve impulses

1.     Resting neuron

2.    Depolarized neuron