IPHY 3410 - Chapter 12: Nervous System

CNS (central nervous system)

brain and spinal cord

integration and interpretation

sensory input

dictates motor response

PNS (peripheral nervous system)

cranial nerves/branches, spinal nerves/branches

neurons transport sensory input toward CNS and motor output away from CNS

sensory input

sensory receptors monitor internal and external changes

gathered stimuli send to CNS for processing

integration of information

processes information from multiple receptors and dictates a response

motor output

initiation and activation of motor response

interneurons

processing of sensory input activation of motor output ALWAYS CNS CONTAINED

afferent

to brain

efferent

to body

neurons

able to respond to stimulus & carry an electrical impulse

Excitable cells (carry electrical impulse)

supporting cells

help neurons to function more efficiently

Non-excitable cells (cannot carry electrical impulse)

cell body (soma)

single nucleus and organelles of neuron

dendrite

receptive regions, carry info toward cell body, none to multiple

axon

carry info away from cell body, one per neuron, can be short or long, end at axon terminals, surrounded by myelin sheath

axon terminals

end of neuron, synapse

schwann cell

surrounds axon

myelin sheath

insulates axon so action potential can travel quickly

myelinated axon

fastest signal

schwann cell wraps around single axon

unmyelinated axon

schwann cell surrounds multiple axons

slower conduction

oligodendrocyte

cell that forms myelin sheath in CNS.

multiple sclerosis

Gradual destruction of myelin in CNS (oligodendrocytes)

Plaques develop when myelin is damaged —> disrupts action potential

Motor and sensory problems develop over time

autoimmune, unk cause

neuron vs nerve

neuron: cell that carries electrical impulse

nerve: collection of many neurons

nerve

collection of axons in PNS (motor and sensory)

tract

collection of axons in CNS (interneurons)

multipolar neuron

most common

axon and multiple dendrites (2+)

motor neurons and interneurons

bipolar neuron

found in a few locations (but in abundance): retina

axon and single dendrite

special sensory

unipolar (pseudo-unipolar) neuron

typical sensory neuron (afferent)

single axon connected via short process to cell body.

no dendrites!

sensory neurons (PNS)

afferent

cell bodies clustered in ganglia

unipolar

motor neurons (PNS)

efferent

cell bodies within CNS

multipolar

interneurons

neurons of the CNS

multipolar

endoneurium

surrounds axon

thin reticular CT

perineurium

surrounds fascicle of axons

fibrous CT

epineurium

surrounds whole nerve

dense irreg CT

synapse

site wehre neurons communicate w each other or w other cells

presynaptic neuron

carries impulse toward synapse

postsynaptic neuron

carries impulse away from synapse

end at axon terminals

synaptic vesicles

vesicles in the axon terminal containing neurotransmitters

synaptic cleft

where neurotransmitters are released in the synapse of two neurons

axodendritic synapse

pre axon attached to post dendrite

most common

axosomatic synapse

pre axon attached to post cell body

axoaxonic synapse

pre axon to post axon

more common in brain

CNS supporting cells

astrocytes, microglia, ependymal cells, oligodendrocytes

PNS supporting cells

satellite cells, schwann cells

astrocytes

most abundant supporting cell

nourish neurons (transfer glucose)

take up excess neurotransmitters from EC space

microglia

smallest and least abundant

protect brain from pathogens

also remove dead/dmg neural tissue

ependymal cells

make up ciliated simple cuboidal epithelium of the CNS.

ventricles of brain

canal of spinal cord

cilia circulate cerebral spinal fluid (CSF)

satellite cells

surround cell body, prevent info “crossover”

ganglia

clusters of neuronal cell bodies

Tic Douloureux (trigeminal neuralgia)

nerve disorder that causes sensation or stabbing pain or shock in regions of the face