Biology Quizlet: Nervous System

central n.s. (CNS)

Brain and spinal cord; processes information.

peripheral n.s. (PNS)

Nerves outside CNS; connects body to CNS.

neuron

Cell that sends electrical and chemical signals.

sensory neuron

Sends info from body to CNS.

motor neuron

Sends commands from CNS to muscles/glands.

interneuron

Connects neurons within the CNS.

dendrite

Receives signals from other neurons.

axon

Carries signals away from the cell body.

axon terminals

Ends of axon; release neurotransmitters.

cell body

Contains nucleus; processes signals.

synapse

Gap between neurons where signals are passed.

resting potential (polarized)

Neuron at rest; inside is negative.

action potential (AP) / nerve impulse

Electrical signal sent down the axon.

depolarization

Sodium enters; inside becomes positive.

repolarization

Potassium exits; returns to resting state.

hyperpolarization

Membrane becomes more negative than resting.

Sodium (Na+)

Ion that enters during depolarization.

Potassium (K+)

Ion that exits during repolarization.

Calcium (Ca2+)

Triggers neurotransmitter release at axon end.

sodium channel

Lets Na+ into neuron during depolarization.

potassium channel

Lets K+ out during repolarization.

sodium / potassium pump

Restores resting state using ATP (3 Na+ out, 2 K+ in).

calcium channel

Opens at axon terminal to let in Ca2+.

neurotransmitter

Chemical that carries signal across synapse.

pre-synaptic cell

Neuron sending the signal.

post-synaptic cell

Neuron or cell receiving the signal.

neuromuscular junction (NMJ)

Synapse between motor neuron and muscle.

"All or None" Response

Neuron fires fully or not at all.

threshold

Minimum stimulus needed to start an action potential.