unit 2 part 1 (9-13) Flashcards
neuron
nerve cells
cell body
part of neuron that contains nucleus
dendrites
extensions of cell body, receives and integrates messages
axon
neuron extension; passes messages through branches to other neurons or muscles
myelin sheath
fatty tissue encasing axons to speed up impulses
glial cells / glia
cells in ns that protect neurons. learning, thinking, memory
action potential
brief electrical charge that travels down axon
threshold
minimum stim required to trigger neural impulse
refactory period
brief resting pause after a neuron is fired
all or none response
neuron reaction of firing or not firing
synapse
space between axon tip of sending neuron and dendrite/cell body of receiving neuron
neurotransmitters
chemical messengers that cross synaptic gap brtween neurons
reuptake
neurotransmitter reabsorption by sending neuron
endorphins
natural painkillers
agonist
increase neurotransmitter action
antagonist
decrease neurotransmitter action
nervous system
bodys fast communication network; all of the nerve cells of central and peripheral nervous systems
central nervous system
brain and spinal cord
peripheral nervous system
sensory and motor neurons connecting cns to body
nerves
bundled axons connecting cns to muscles, glands, organs
sensory/afferent neurons
carry info from tissue to brain and spinal cord
motor/efferent neurons
carry outgoing info from brain and spinal cord to muscles and glands
interneurons
neurons within brain and spinal cord
somatic nervous system
PNS; voluntary control of skeletal muscles
autonomic nervous system
PNS; controls muscle glands and internal organs
sympathetic ns
gives energy; arouses (fight or flight)
parasympathetic ns
calms, conserves energy
reflex
automatic response to stimuli; spinal cord
endocrine system
set of glands that secrete hormones into bloodstream
hormones
chemical messengers that travel via bloodstream; endocrine glands