Chapter 2 Flashcards
NEURON
a specialized cell transmitting nerve impulses; a nerve cell.
DENDRITES
a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
CELL BODY
the nucleus-containing central part of a neuron exclusive of its axons and dendrites that is the major structural element of the gray matter of the brain and spinal cord, the ganglia, and the retina — called also perikaryon, soma.
AXON
the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.
MYELIN SHEATH
the insulating covering that surrounds an axon with multiple spiral layers of myelin,
TERMINAL BUTTONS
Tiny bulblike structures at the end of the dendrites, which contain neurotransmitters that carry the neuron’s message into the synapse.
NEUROTRANSMITTERS
a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.
SYNAPSE
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
RECEPTOR
SITES
the part of a nerve that receives and reads chemical signals (neurotransmitters) from other nerves to transmit the electrical signals that transfer information through the brain and nervous system.
THRESHOLD
the level of strength a stimulus must reach to be detected.
ACTION POTENTIAL
threshold in a neuron is the point of depolarization at which the neuron fires, transmitting information to another neuron.
ALL-OR-NONE
PRINCIPLE
law is a principle that states that the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus.
NEURAL FIRING
An action potential is part of the process that occurs during the firing of a neuron. During the action potential, part of the neural membrane opens to allow positively charged ions inside the cell and negatively charged ions out. … When the charge reaches +40 mv, the impulse is propagated down the nerve fiber.
EXCITATORY
NEUROTRANSMITTERS
Excitatory neurotransmitters are neurotransmitters that increase the likelihood that a nerve cell will produce an action potential, an electrochemical impulse that nerve cells use to transmit signals
INHIBITORY
NEUROTRANSMITTERS
A neurotransmitter that generally activates receptors that have reversal potentials more negative than threshold for action potential firing.
ACETYLCHOLINE
a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter.