Chapter 3 Flashcards
central nervous system
brain & spinal cord
peripheral nervous system
- all the other nerves in the body
- divided into somatic and autonomic (inside)
3 types of neurons
sensory, motor, & interneurons
sensory neurons
- detect info from world
- somatosensory provide info from skin and muscles
motor neurons
direct muscles to contract/relax
interneurons
communicate within short circuits
parts of a neuron
dendrites, cell body, axon, and terminal buttons
dendrites
short, branchlike appendages that detect chemical signals
cell body
- aka soma
- collect & integrate info
axon
- transmit signals
- can be really long
- covered in a myelin sheath
terminal buttons
at the end of the axon
synapse
gap where chemical communication occurs between neurons
what is a neuron covered with
a semipermeable membrane that allows ions to travel through ion channels
resting membrane potential
inside a neuron is slightly more negative than outside, so it’s polarized
sodium potassium pump
increases potassium & decreases sodium within cell to maintain resting potential
action potential
aka neural firing
electrical signal that passes along the axon
types of chemical signals
excitatory (depolarize cell membrane by making inside more +) or inhibitory (increase polarization by making inside more -)
what happens when a neuron fires
- sodium gates open–> sodium ions rush in and inside becomes +
- potassium gates open–> K rushes out and inside becomes even more +
- Na then K gates close, cell is even more - than normal
- K-Na pump restores resting state
myelin sheath
insulates axons and allows signals to travel faster
made of glial cells
nodes of Ranvier
small gaps of exposed axon between the sheath
all or none principle
a neuron fires with the same potency each time or not at all
what are the neurons that send/receive signals called
presynaptic sends and postsynaptic receives
neurotransmitters
- made in axon, stored in vesicles in terminal buttons
- convey signals across synapses
receptors
specialized protein molecules located on receiving membrane that respond to a specific neurotransmitter and can open or close ion channels
three major events that terminate a neurotransmitter’s influence
reuptake, enzyme deactivation, or autoreception
reuptake
a neurotransmitter is taken back into the presynaptic terminal buttons
enzyme deactivation
an enzyme destroys a neurotransmitter
autoreceptors
monitor how much neurotransmitter has been released and detect excesses
agonist vs. antagonist
agonists are drugs that enhance actions of neurotransmitters by blocking reuptake or mimicking a neurotransmitter, antagonists inhibit them