Nervous System Vocabulary** Flashcards
Sheath formed from schwann cells on the exterior of some axons
Neurilemma
Depolarization and repolarization along an axon
Nerve impulse
Nerve cells
Neurons
Chemicals that axons secrete on the effectors
Neurotransmitters
Specialized cells of the nervous system that support, nourish, and protect neurons
Neuroglial cells
A neuron that transmits impulses from the CNS to the effector
Motor neuron
Fatty layers formed from certain neuroglia that surround axons, providing insulation
Myelin sheath
An electrical charge on a cell membrane surface due to an unequal distribution of positive and negative ions on either side of the membrane
Polarized
The difference in electrical charge between the inside and the outside of an undisturbed nerve cell membrane
Resting potential
A type of neuroglial cell that surrounds an axon of a peripheral neuron, forming the neurilemma sheath and myelin
Schwann cell
The space between 2 cells forming a synapse
Synaptic cleft
Neurons that transmit impulses from receptors to the CNS
Sensory neurons
Process that requires energy to move a substance across a cell membrane, usually against the concentration gradient
Active transport
The sequence of electrical changes that occurs in a portion of a nerve cell membrane that is exposed to a stimulus that exceeds the membrane’s threshold
Action potential
A nerve fiber that conducts an impulse away from the neuron cell body
Axon
A type of neurotransmitter which is a biochemical secreted at axon ends of many neurons; transmits nerve messages across synapses
Acetylcholine
Portion of nerve cell that included a cytoplasmic mass and a nucleus, and from which nerve fibers extend
Cell body
Process of a neuron that receives input from other neurons
Dendrites
The loss of an electrical charge on the surface of a cell membrane
Depolarized
A neuron between a sensory neuron and a motor neuron
Interneuron
Simulation level that must be exceeded to elicit a nerve impulse
Threshold
Membranous cytoplasmic sacs formed by infoldings of the cell membrane
Vesicle
Space between Schwann cells
Nodes of Ranvier
A change or signal in the environment that helps nerves to react in some way
Stimulus
The restoration of a polarized state across a membrane.
Repolarization
A mechanism of active transport that moves potassium ions into and sodium ions out of a cell.
Sodium-potassium pump
a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances.
Blood-brain barrier
The spreading of something
Propagation
a neuron conducting impulses outwards from the brain or spinal cord
Efferent neurons
a neuron conducting impulses inwards to the brain or spinal cord
Afferent neurons
A small mass of differentiated tissue
Node
Ends of the axon that release neurotransmitters
Axon terminal
a period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation.
Refractory Period
The potential difference between the region inside the membrane and the region outside the membrane
Resting potential
Neurons are depolarized sufficiently
Threshold potential
