A&P - Chapter 18 (Part 3) Flashcards
What do Schwann cells do? (2)
- Support nerve fibres
2. Forms a myelin sheath on axons in the PNS
What do schwann cells have a similar function to?
Oligodendrocytes in the CNS
- wraps itself around the axons of the neurons
What does myelin act as?
An insulator
What is myelin formed by in the CNS?
Oligodendrocytes
What is myelin formed by in the PNS?
Schwann cells
What are unmyelinated spaces called?
Nodes of Ranvier
What is the node of Ranvier capable of generating? Why?
- Electrical activity
- saltatory conduction - Not insulated
Saltatory conduction
Allows for rapid and effective transmission of a nerve impulse
Saltatory
Jumping
What are neurons?
Excitable cells that initiate and conduct impulses that make all nervous system functions possible
- structural/functional units of the NS
What are the 3 main parts of the nervous system?
- Dendrites
- Cell body
- Axon
What does the cell body contain? (2)
- Nucleus
2. Organelles
What are dendrites?
Branching projections
What do dendrites do?
They conduct impulses to the cell body
What is the main part of the neuron?
The cell body
Where is the cell body found?
In the CNS
- or close by
Axon
Long, single projection from the cell body
Is the axon myelinated?
Sometimes
What does the axon do?
Transmits impulses away from the cell body
How do the distal tips of the axon terminate?
In a synaptic knob
What are the distal ends in sensory neurons of dendrites?
Shorter
What are the 3 types of structures of a neuron?
- Multipolar
- Bipolar
- Unipolar
Multipolar structure
Multiple extensions from the cell body
Bipolar structure
Exactly 2 extensions from the cell body
Unipolar structure
Exactly 1 extension from the cell body
What are 3 types of functions of a neuron?
- Sensory
- afferent - Motor
- efferent - Interneurons
- sensory to motor
What happens if neurons are damaged?
They wont duplicate because once damaged they cant repair
What type of nervous cell is most likely to be cancerous? Why?
- Glia cells
2. Because they reproduce
