Neural Signalling and Synaptic Transmission Vocabulary

A set of vocabulary flashcards covering key terms and concepts related to neural signalling, action potentials, myelination, synaptic transmission, exogenous chemicals, and sensory perception.

Neuron

Specialised cell of the nervous system that carries electrical impulses.

Dendrites

Short branched fibres that receive signals from other neurons or receptors.

Cell Body

The part of a neuron that contains the nucleus and receives incoming signals.

Axon

A single elongated fibre that carries the electrical impulse away from the cell body.

Resting Potential

The electrical charge difference across a neuron's plasma membrane when it is not transmitting a signal, equal to $-70\,mV$ in neurons.

Sodium-Potassium Pump ($Na^+/K^+$ Pump)

A transmembrane protein that uses ATP to actively transport $3\,Na^+$ out of the neuron for every $2\,K^+$ pumped in against their concentration gradients.

Myelin Sheath

A fatty substance that wraps around axons to form an insulating layer.

Giant Squid Axon

A non-myelinated axon with a large diameter of $500\,\mu m$ that conducts impulses at $25\,m/s$ to drive escape responses.

Synapse

A junction where a neuron connects with another neuron or target cell.

Presynaptic Membrane

The membrane at the end of the axon terminal where depolarization opens voltage-gated calcium ion channels.

Depolarization

The phase of an action potential where positively charged $Na^+$ ions enter the neuron, making the inside less negative and increasing potential from $-70\,mV$ to $+30\,mV$.

Repolarization

The phase of an action potential where $K^+$ ions move out of the neuron, returning the internal charge back to a negative value of $-70\,mV$.

Hyperpolarization

A state where the membrane potential drops below resting potential to around $-80\,mV$, making the neuron less likely to fire.

Saltatory Conduction

The process by which an action potential jumps from one node of Ranvier to the next, conducting signals much faster in myelinated axons.

Schwann Cells

Cells that assist in wrapping the myelin sheath around an axon.

Nodes of Ranvier

Gaps in the myelin sheath along an axon where ion pumps and channels are clustered.

Exogenous Chemicals

Substances originating from outside the body that alter signals across the synapse.

Neonicotinoids

Synthetic insecticides that resemble nicotine and act as agonists by binding to nicotinic acetylcholine receptors.

Cocaine

An exogenous chemical that acts at dopamine synapses by blocking reuptake transporters, allowing dopamine to remain in the cleft and continually stimulate the postsynaptic neuron.

Inhibitory Neurotransmitters

Chemicals that make the postsynaptic membrane potential more negative (below threshold), producing hyperpolarization and making an action potential less likely.

Summation

The process by which signals from multiple presynaptic neurotransmitters are combined at the postsynaptic neuron to determine whether an action potential will fire.

Free Nerve Endings in the Skin

Sensory structures containing channels for positively charged ions that open in response to stimuli such as high temperatures, acid, or capsaicin to transmit pain impulses.

Consciousness

The state of being aware of and able to think of one's own existence, thoughts, and surroundings, serving as an emergent property arising from system interactions.