Ch 3- neurons and neural transmission Flashcards
(31 cards)
sensory neurons
make initial contact with the environment and are responsible for carrying the message inward toward the spinal cord and brain
interneurons
most plentiful type of neuron, make no direct contact with the world but they convey information from one internal processing site to another
motor neurons
carry messages and commands away from central nervous system to the muscles and glands that produce responses
glial cells
cells that fill in space between neurons, remove waste, or help neurons to communicate efficiently
myelin sheath
an insulating material that protects the axon and helps to speed up neural transmission
reflexes
largely automatic body actions- such as the knee jerk- that are controlled primarily by spinal cord pathways
dendrites
look like tree branches. primary information receivers,
soma
cell body of the neuron, also called metabolic center, where genetic material is stored
axon
the long tail-like part of a neuron that serves as the cell’s transmitter. the electric signal called the action potential travels down the axon
terminal buttons
the tiny swellings at the end of the axon that contain chemicals important to neural transmission
synapse
small gap between the terminal buttons of a neuron and the dendrite or cell body of another neuron
direction of information flow in a neuron
dendrites, soma, axon, terminal buttons
Messages travel ___ from one point to another within a neuron, but the message is transmitted ____ between neurons.
electrically, chemically
resting potential
the tiny electrical charge in place between the inside and the outside of the resting neuron
main ions in neural transmission
positively charged sodium and potassium and negatively charged chloride
action potential
the all-or-none electrical signal that travels down a neuron’s axon
excitatory message
ion channels open, sodium ions flow into the cell (depolarization), moves electrical potential of cell from negative to 0
inhibitory message
cell membrane pushes more positive ions out of the cell or allows negative ions to move in (hyperpolarization), electrical potential of the cell becomes more negative
axon hillock
near the point where the axon leaves the cell body, all of the excitatory and inhibitory potentials combine.
When will a cell “fire” an action potential?
If enough excitatory messages have been received (aka the net electrical potential inside the cell has become sufficiently less negative)
Nodes of ranvier
the gaps in insulation (myelin sheath) that permit action potential to jump down the axon rather than travel from point to point
neurotransmitters
chemical messengers that relay information from one neuron to the next
glutamate
most common neurotransmitter in the brain, excitatory neurotransmitter, involved in memory
acetylcholine
a neurotransmitter that plays multiple roles in the central and peripheral nervous systems, including excitation of muscle contractions
