Axons

pgs. 40 - 49

axon hillock

a swelling of the axon where it joins the soma (links with axon initial segment)

axon initial segment

a short, specialized segment of axon adjacent to the soma where neuronal action potentials are usually initiated (also spike initiation zone)

axon terminal

the end region of an axon, usually a site of synaptic contact w/another cell (also terminal bouton/presynaptic terminal)

terminal arbor

many short branches at the end of an axon that forms one or more synapses

innervation

neuron makes synpatic contact w/another cell

synaptic cleft

narrow space between pre- & postsynaptic membrane

synaptic transmission

transfer of information at the synapse to another neuron

neurotransmitter

a chemical released by a presynaptic element upon stimulation that activates postsynaptic receptors

anterograde transport

axoplasmic transport from a neuron’s soma to the axon terminal

retrograde transport

axoplasmic transport from an axon terminal to soma

dendritic tree

all the dendrites of a single neuron

receptors

1) a specialized protein that detects chemical signals (such as NTs) and initiates a cellular response, 2) a specialized cell that detects environmental stimuli and generates neural responses

dendritic spines

a small sac of membrane that protrudes from the dendrites of some cells and receives synaptic input

neuron type

a subset of neurons that share similar structure (patterns of dendrites and axons)

neuron w/single neurite

unipolar

neuron w/2 neurites

bipolar

neuron w/3 or more neurites

multipolar

stellate cell

a neuron characterized by a radial, star-like distribution of neurons

pyramidal cell

a neuron characterized by a pyramid-shaped cell body and elongated dendritic tree; found in cerebral cortex

spiny neuron

a neuron with dendritic spines

aspiny neuron

a neuron with no dendritic spines

primary sensory neurons

a neuron specialized to detect environmental signals at the body’s sensory surfaces

motor neurons

a neuron that synapses on a muscle cell and causes muscle contraction

interneurons

any neuron that is not a sensory/motor neuron - also describes a CNS neuron whose axon doesn’t leave the structure in which it resides

projection neurons

neurons that have long axons extending from 1 part of the brain to the other

local circuit neuron

neurons that have short axons