Module 5 (Neurons and Supporting Cells) Flashcards
What are the 2 principle cell types in the NS
Neurons (nerve cells) and supporting cells
What are neurons
Cells that are excitable and can generate and transmit rapid electrical signals to other neurons
Neuron structure
Structural units of the NS
Cell body
Dendrites
Axon
Direction of nerve impulses
Unidirectional so they only occur in one direction
Do not travel in the opposite direction
Pathway of nerve impulses
From the dendrites to the call body through the axon to reach dendrites of adjacent neurons or target organs
3 classifications of neurons
Pseudounipolar (unipolar)
Bipolar
Multipolar
Classification of neurons
Can be classified based on the number of cellular processes (dendrites and axons) that extend from the cell body
Pseudounipolar (unipolar) neurons
Have one cellular process that splits into a dendrite and an axon
What kind of nerves are pseudounipolar (unipolar)
General sensory nerves
Bipolar neurons
Have one dendrite and one axon that extend directly from the cell body
Have 2 distinct cellular processes
Where are bipolar neurons found
Only in special senses, like sight and hearing
Multipolar neruons
Have multiple dendrites and one axon
Summing to 3 or more cellular processes
What type of neurons are multipolar
Motor neurons
Most common
Supporting cells of the CNS
Known as neuroglia or glia
Functions of supporting cells
Protect and support neurons
Aid in sending signals between neurons to improve communication
Do not generate or transmit nerve impulses
4 type of supporting cells in the CNS
Astrocytes
Microglia
Ependymal
Oligodendrocytes
What are astrocytes
Large star shaped cells with numerous processes
Communicate with neurons and blood vessels to maintain the integrity of the neural tissue
Which cell is the most abundant of the glial cells in the CNS
Astrocytes
What are microglia
Small glial cells, perform many protective functions in the CNS
Able to phagocytose and eliminate waste products from other cells
What is the least common type of supporting cell
Microglia
What are ependymal
Cuboidal in shape and line cavities of the brain and spinal cord
Assist in the production, circulation, and monitoring of cerebrospinal fluid (CSF)
What are oligodendrocytes
Wrap around axons in the CNS to form myelin sheath
Have many processes that extend to myelinate axons
What is myelination
Important function of some neuroglia to wrap myelin around parts of an axon
Insulates the axon and increases the speed at which electrical signals can travel down the axon
What is myelin composed of
Mainly fat and appears white
What are unmyelinated regions of an axon called
Nodes of Ranvier (neurofibril nodes)
Disease associated with demyelination of axons
Multiple sclerosis
Leads to neurological symptoms
Supporting cell of the PNS
Schwann cell
What are Schwann cells
Equivalent to oligodendrocytes as they from myelin sheaths around axons in the PNS
