Module 1.3A Flashcards
Neurons
Neuron
A nerve cell; the basic building block of the nervous system.
Cell Body
The part of a neuron that contains the nucleus; the cell’s life support center.
Dendrites
A neuron’s often bushy, branching extensions that receive and integrate messages, conducting impluses toward the cell body.
Axon
The segmented neuron extensions that passes messages through its branches to other neurons or to muscles or glands.
Myelin Sheath
A fatty tissue layer segmentally encasing the axons of some neurons; it enables vastly greater transmission speed as neural impulses hop from one node to the next.
Glial Cells (glia)
Cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.
Action Potential
A neural impulse; a brief electrical charge that travels down an axon.
Threshold
The level of stimulation required to trigger a neural impulse.
Refractory Period
In neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.
All-or-none response
A neuron’s reaction of either firing (with a full-strength response) or not firing.
Synapse
The junction between the axon tip of the sending neurons and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
Neurotransmitters
Chemical messengers that cross the synaptic gap between neurons. When released by the sending euro, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
Reuptake
A neurotransmitter’s reabsorption by the sending neuron.
Endorphins
“morphine within”; natural, opioid-like neurotransmitters linked to pain control and to pleasure.
Agonist
A molecule that increases a neurotransmitter’s actions.
