Action Potential Propagation and Synaptic Transmission

Vocabulary terms covering action potential origination, refractory periods, axonal propagation, myelination, and the discovery of chemical neurotransmission.

Taurine

A substance found in energy drinks that acts as a GABA receptor agonist.

Axon Hillock

The slightly swollen region adjacent to the soma where action potentials typically originate due to a thinner membrane and a resting potential closer to threshold.

Absolute Refractory Period

The phase during repolarization where open voltage-dependent potassium channels prevent the neuron from producing another action potential, regardless of stimulus size.

Relative Refractory Period

The period during the undershoot following an action potential when a second action potential can only be triggered by an exceptionally large stimulus.

Oligodendrocyte

The type of glial cell that produces myelin in the central nervous system, which includes the brain and spinal cord.

Schwann Cell

The type of glial cell that provides myelin to axons located in the peripheral nervous system.

Nodes of Ranvier

Unmyelinated gaps along an axon where voltage-dependent channels are located and electrical resistance is lower across the membrane.

Saltatory Conduction

The jumping of an action potential from node of Ranvier to node of Ranvier, which significantly increases the speed of neural conduction along an axon.

Multiple Sclerosis (MS)

A neurological condition involving the selective degradation of myelin, which disrupts the conduction speed and precise timing of action potentials needed for coordinated movement.

Phantom Limb Pain

A condition where an individual reports pain in an amputated or missing limb despite the lack of sensory nerve activity at the periphery.

Charles Sherrington

The British scientist who deduced from reflexes (such as simultaneous contraction of one muscle and relaxation of another) that signal modification occurs in the synapse.

Otto Loewi

The scientist who demonstrated through a frog heart experiment that neurons communicate with target tissues via chemical messengers released into the fluid.

Ringer's Solution

A nutrient-containing fluid that mimics the internal fluid of the thoracic cavity and keeps dissected tissues or organs viable for extended periods.

Vagus Nerve

A nerve that, when electrically stimulated in Otto Loewi's frog heart experiment, causes the heart rate to decrease.

Accelerator Nerve

A nerve connected to the frog heart that, when stimulated in Otto Loewi's preparation, causes the heart rate to increase.

Chemical Transmission

The principle that while information within a single neuron is electrical, information transfer across the synapse between neurons is chemical.