Nervous System (IB Biology SL - C2.2)

axon

the long, narrow body of a neuron

myelin sheath

a fatty white, insulating substance surrounding the axon of some nerve cells, produced by glial cells

nodes of Ranvier

gaps in the myelin sheath; allows for saltatory conduction

synaptic cleft

the space between adjacent neurons; between the axon terminus and neighbouring dendrite

calcium (Ca)

ion responsible for triggering neurotransmitters to move toward the synaptic cleft

saltatory conduction

mode of impulse movement along a myelinated axon

sodium (Na)

ion that initiates the action potential

transporter proteins

membrane channels on the axon terminus for the re-uptake of used neurotransmitters

potassium (K)

ion found at higher concentration inside the neuron at resting potential

threshold potential

the point of stable imbalance at which an action potential will be realized

oscilloscope trace

the graph use to show a neural impulse

resting potential

the state with a ionic reading of -70mV (in humans)

action potential

depolarization and repolarization

neurotransmitter

compounds released from the axon terminus into the synapse due to Ca+ entering the cell

acetylcholine

common neurotransmitter used to signal muscle movement

acetylcholinesterase

enzyme in the synaptic cleft that eliminated acetylcholine

receptor proteins

molecular structures on the dendrites that receive neurotransmitters

dendrite

branched extensions from the soma of a neuron

neonicotinoids

chemicals that mimic the acetylcholine neurotransmitter and are highly neurotoxic to insects, leading to paralysis and death

depolarization

beginning of the action potential when Na+ enter the axon through Na+ channels, followed by K+ leaving the axon via K+ channels

repolarization

second part of the action potential, caused by reentry of K+ into the cell while Na+ exits the cell.