Glossary
- Absolute Refractory Period
- time during an action period when another action potential cannot be generated because the voltage-gated Na+ channel is inactivated
- All-or-None
- the principle that the response of a neuron or muscle fiber to a stimulus at any strength above the threshold is the same, that the muscle fiber or neuron cell responds completely or not at all
- Continuous Conduction
- slow propagation of an action potential along an unmyelinated axon owing to voltage-gated Na+ channels located along the entire length of the cell membrane
- Depolarization
- change in a cell membrane potential from rest toward zero
- Excitatory
- results in the membrane potential being closer to threshold
- Hyperpolarize
- a change in a cell's membrane potential that makes it more negative
- Inhibitory
- the membrane potentail gets farther away from threshold and is less likely to be able to send an action potential
- Leakage Channel
- ion channel that opens randomly and is not gated to a specific event, also known as a non-gated channel
- Ligand-gated Channels
- another name for an ionotropic receptor for which a neurotransmitter is the ligand
- Myelin Sheath
- lipid-rich layer of insulation that surrounds an axon, formed by oligodendrocytes in the CNS and Schwann cells in the PNS; facilitates the transmission of electrical signals
- Potential (membrane potential)
- distribution of charge across the cell membrane, based on the charges of ions
- Repolarization
- return of the membrane potential to its normally negative voltage at the end of the action potential
- Resting Membrane Potential
- the difference in voltage measured across a cell membrane under steady-state conditions, typically -70 mV
- Saltatory Conduction
- quick propagation of the action potential along a myelinated axon owing to voltage-gated Na+ channels being present only at the nodes of Ranvier
- Spatial Summation
- combination of graded potentials across the neuronal cell membrane caused by signals from separate presynaptic elements that add up to initiate an action potential
- Sodium Potassium Pump
- membrane-bound transporter found in nearly all cells that transports potassium ions into the cytoplasm from the extracellular fluid while simultaneously transporting sodium ions out of the cytoplasm to the extracellular fluid
- Temporal Summation
- combination of graded potentials at the same location on a neuron resulting in a strong signal from one input
- Threshold
- millivolt level that must be reached before the action potential can be produced
- Voltage-gated Channel
- ion channel that opens because of a change in the charge distributed across the membrane where it is located
Grant and Other Information
Except where otherwise noted, this work by The Community College Consortium for Bioscience Credentials is licensed under a Creative Commons Attribution 4.0 International License.
Text from Michael Ayers, M.S. for c3bc.
Other text from BioBook licensed under CC BY NC SA and Boundless Biology Open Textbook licensed under CC BY SA.
Other text from OpenStaxCollege licensed under CC BY 3.0. Modified by Alice Rudolph, M.A. and Andrea Doub, M.S. for c3bc.
Instructional Design by Courtney A. Harrington, Ph.D., Helen Dollyhite, M.A. and Caroline Smith, M.A. for c3bc.
Media by Brittany Clark, Jose DeCastro, Jordan Campbell and Antonio Davis for c3bc.
This product was funded by a grant awarded by the U.S. Department of Labor's Employment and Training Administration. The product was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership.
;
