organization of nervous system Flashcards
What are interneurons?
have short axons and produce direct effects only in their immediate neighbourhood
What apparatus does the cell body of a neuron contain?
The nucleus, Golgi apparatus, ribosomes and mitochondria, nissl bodies
what proportion of the neurons of the cerebral cortex are pyramidal cells?
60%
what are Nissl Bodies?
Rough Endoplasmic reticulum densely packed with ribosomes
What is the purpose of Nissl Bodies?
They allow high rates of protein synthesis.
What is the range of cell body size?
5- 120 micrometers
What are dendrites
Highly branched extensions of the cell body
What is the length of axons?
up to 1 mm
What surface area of the neuron do the dendrites usually constitute?
Up to 90% of the surface area of the neuron
How are the dendrites of a neuron arranged?
They are arranged in the cell-typical pattern called a dendritic tree
What do the dendrites of spiny neurons have?
Dendrites on spiny neurons are covered with hundreds of tiny projections called dendritic spines
What are nerves lacking dendritic spines called?
Aspiny Neurons
what is the site of origin of an axon called?
Axon Hillock
What is the range of diameters of the axons?
0.2 - 20 micrometers in humans
What is the range of lengths of an axon?
from a few micrometers to over a meter.
what are the branches of axons usually called
Axon collaterals
What are the swollen ends of the axon called?
terminals/ boutons
What do the ends of the axons contain?
Mitochondria and vesicles
Some axons have swellings long their length, what are they called?
Varicosities
two differences in the anatomy of an axon vs dendrite
Axons are less highly branched an do not have protein synthetic machinery
How are the proteins made in the cell body transported into and along the axon?
Via axoplasmic transport
Axon terminals are rich in which organelle?
Mitochondria
How can nerve cells be classified?
They are classified by their structure, connections and neurotransmitters
What are neurons with one; two; or more than two neurites called?
Unipolar, bipolar and multipolar neurons respectively.