The Nervous System Flashcards
How many pairs of cranial nerves are there?
12
How can you divide the nervous system at the gross level?
Brain, spinal cord and nerves.
How many pairs of spinal nerves are there?
31
What are the two types of cell in the nervous system, and in what proportion are they present?
Neurons (10%)
Glia (90%)
What glia are present in the CNS, and what are their functions?
Oligodendrocytes - myelination of the axons
Astrocytes - physical support of neurons, phagocytosis, constitute blood brain barrier, assist in transfer of nutrients and waste products between neuron and blood stream, break down glucose to lactate for neuronal nourishment.
Microglia - inflammatory response, phagocytes.
Ependyma - ciliated cells lining ventricles and central canal of spinal cord, promote circulation of spinal cord.
What are the glia of the PNS, and what are their functions?
Schwann cells - myelination of axons.
Microglia - immunity and inflammation, phagocytosis.
Satellite cells - physical support of neurones.
What does the cell body contain?
Nucleus
Nissl substance - RER
Golgi
Some cell bodies have dendrites.
What is the diameter of a cell body?
4-120um diameter
What is a collection of cell bodies?
Grey matter
What is a collection of axons?
White matter
What is grey matter in the CNS?
Nerve nuclei
What is grey matter in the PNS?
Ganglia
What is the membrane surrounding the axon called?
Axonal membrane
Where are the nodes of ranvier found, and what is their function?
Between the Schwann cells wrapped around the axon.
Speeds up nerve impulse as it causes saltatory conduction of the impulse.
What is the end of the axon called?
Axonal terminal
What is the axonal membrane that is covered in a Schwann cell called?
Internodal membrane
What is the first part of the axon called?
Initial segment.
What is the axonal hillock?
Part of the cell body that connects to the axon.
How is the speed of nervous impulse related to the level of myelination?
Directly proportional - CV=6FD
How thick is the myelin in a thin axon?
0.5um