Nerve Signaling

Nerve Signaling

The process of transmitting electrical signals along the plasma membrane of a neuron.

Continuos conduction

The slow conduction of action potentials along unmyelinated fibers with smaller diameters.

Saltatory conduction

The fast conduction of action potentials along myelinated fibers with large diameters, where the action potential jumps from node to node.

Excitability

The ability of neurons to generate electrical signals.

Conductivity

The ability of neurons to conduct electrical signals.

Action potential

A nerve impulse, which is an electrical signal that travels along the plasma membrane of a neuron.

Membrane potential

The difference in electrical charge between the inside and outside of a cell, caused by the difference in charged ions on both sides of the plasma membrane.

Ion channels

Integral membrane proteins that allow the movement of ions across the membrane through facilitated diffusion.

Sodium channels

Ion channels specific for sodium ions that are gated and opened by a neurotransmitter.

Potassium channels

Ion channels specific for potassium ions that are voltage gated and open during repolarization of the membrane.

Gated ion channels

Ion channels that open or close in response to specific stimuli, such as changes in voltage or the binding of a neurotransmitter.

Voltage-gated channels

Ion channels that open when a particular threshold voltage is reached.

Ligand-gated channels

Ion channels that open in response to the binding of a chemical, such as a neurotransmitter.

Stimulus-gated channels

Ion channels that open in response to a specific stimulus, such as pressure or chemicals.

Local potentials

Small changes in the membrane potential that occur in response to the opening of stimulus-gated ion channels.

Threshold

The minimum membrane potential required for voltage-gated sodium channels to open and initiate an action potential.

All-or-nothing principle:

The principle that action potentials either occur fully or do not occur at all.

Refractory period

A period of time during which a second action potential cannot be generated.

Synapse

The junction between two neurons or between a neuron and an effector cell where nerve signals are transmitted.

Electrical synapse

A type of synapse where action potentials are spread by ions moving through gap junctions between cells.

Chemical synapse

A type of synapse where communication is done through the release of neurotransmitters that bind to receptors on the postsynaptic cell.

Synaptic transmission

The process by which neurotransmitters are released from the presynaptic neuron, travel across the synaptic cleft, and bind to receptors on the postsynaptic neuron.

Summation

The adding of two or more inputs on a postsynaptic neuron, where an action potential is triggered if the sum of inputs is enough to reach the threshold.

Divergence

A single neuron with axon collaterals that can branch out to different postsynaptic neurons, allowing information to be sent to different destinations.

Convergence

Multiple presynaptic neurons that converge on a single postsynaptic neuron, allowing information from different sources to be processed into a single pathway or action.

Neurotransmitters

Chemical messengers that are manufactured in the cell body of a neuron, packaged into vesicles, and released at the synapse to bind to receptors on the postsynaptic cell.

Direct effect

When neurotransmitters bind to membrane channels and directly open them to allow ions to enter the cell.

Indirect effect

When neurotransmitters bind to receptors and initiate a cascade of events within the cell to eventually open ion channels.

Inhibitory effect

When neurotransmitters bind to receptors and cause hyperpolarization of the postsynaptic cell, making it less likely to generate an action potential.

Excitatory effect

When neurotransmitters bind to receptors and cause depolarization of the postsynaptic cell, making it more likely to generate an action potential.

Termination of neurotransmitters

The mechanisms by which neurotransmitters are removed from the synaptic cleft, including enzyme degradation, reuptake, and diffusion.