Nerve Ultrastructure Flashcards
Two types of nervous system cells
Nerve cells (neurons) and glial cells
Example of glial cell and function
Schwann Cell - provides lipid sheath to periphery neurones
Key structural components of a neuron cell
Cell body, dendrites, axon and axon terminal
Many neuronal cell bodies can group together to form…
A nucleus in the CNS and a ganglion in the PNS
Dendrites are…
Extended portions of a neurone cell body which receive signals
Axons are…
Long thin structures which transmit a nerve impulse
Myelin sheathes are formed by…
Oligodendrocyte cells in the CNS and Schwann cells in the PNS
Nodes of Ranvier allow…
Saltatory conduction of impulses
Axon terminals allow for the secretion of
Neurotransmitter
Axons of neurons are grouped together in the PNS to form..
Nerves
Connective tissue which surrounds the axon of an individual neuron
Endoneurium
Connective tissue which surrounds the axons of nerve fascicles
Perineurium
Connective tissue which surrounds a nerve
Epineurium
Neurones can be classified by
Structure or function
Unipolar neurones - structure and example
No dendrites, one unbranched axon. Found in the cochlear nucleus of the brain
Pseudounipolar neurones - structure and example
One axon divided into two branches. Sensory neurones
Bipolar neurones - structure and example
Typically one axon and one dendrite - found in the retina
Multipolar neurones - structure and example
Many dendrites and one axon - motor neurones
Sensory (afferent) neurones and motor (efferent) neurones are found in the…
PNS
Intermediate neurones are found in the…
CNS
Multiple sclerosis is when…
Myelin sheathes fail to form around nerves, causing visual, motor and auditory problems
Multiple sclerosis is thought to be caused by…
Autoimmunity of myelin or failure by oligodendrocytes to form myelin
Motor neurone disease is…
A group of diseases which includes ALS (amyotrophic lateral sclerosis). Motor neurones degenerate for unknown reasons and are thought to have dysfunctional mitochondria
MND begins…
In the peripheral nerves, and makes its way to the central nervous system
Life expectancy of MND
3-5 years