Neurons: structural class and circuits

Neurons are structurally classified according to?

the number of processes extending from the cell to the body 

Multipolar neurons structure

several dendrites and one axon

Multipolar neurons are located in:

the brain and spinal cord (interneurons)

most motor (efferent) neurons are MP

Bipolar neurons structure

two processes coming off, one main dendrite and one axon

Bipolar neurons location

retina of the eye, inner ear, and olfactory are of the brain

Unipolar neurons structure

are sensory neurons, cell body is between the axon and dendrite that are brought together and fuse into a single process that divide into two branches from the cell body 

Unipolar neurons location

cell body is located outside CNS in dorsal root ganglia 

What are neural circuits?

neurons organized into complicated networks, each is a functional group or neurons that process a specific kind of info 

Simple series circuit

presynaptic neuron stimulates a single postsynaptic neuron (knee-jerk reflex)

Diverging circuit 

nerve impulse from single presynaptic neuron causes stimulation of (several) increasing number of postsynaptic neurons 

Diverging circuit use

small number of neurons in the brain that govern particular body movement stimulate a much larger number of neurons in the spinal cord

Converging circuit

several presynaptic neurons synapse with a single postsynaptic neuron (receives several impulses from different sources)

Converging circuit usage

single motor neuron synapses with skeletal muscle fibers at NMJ (coordinates body movements)

Reverberating circuit

presynaptic cell causes postsynaptic cell to transmit impulses through the circuit again and again 

Reverberating circuit usage

short: breathing and short term memory

long: waking up, sleeping 

Parallel after-discharge circuit

single presynaptic cell stimulates a group of neurons, which each synapse with a common post synaptic cell

Parallel after-discharge circuit usage

involved with precise activities like mathematical equations