Neuroscience Fundamentals - Neurons, Synapses & Neurotransmitters

The metabolic center of the neuron containing the nucleus, ribosomes, and endoplasmic reticulum. It is responsible for maintaining cell health and synthesizing essential proteins and neurotransmitters.

Branch-like extensions of a neuron that receive chemical signals from other neurons and transmit electrical impulses toward the soma.

The axon is a long projection that conducts electrical signals away from the soma. The axon hillock is the specialized junction connecting the soma to the axon where action potentials are initiated if threshold is reached.

The myelin sheath is a fatty layer formed by Schwann cells (PNS) or oligodendrocytes (CNS) that insulates axons. Gaps in myelin called Nodes of Ranvier enable rapid saltatory conduction of action potentials.

The electrical charge difference across a resting neuronal membrane, typically $-70\text{ mV}$. It is maintained primarily by passive ${\text{K}}^{+}$ leak channels and the ${\text{Na}}^{+}/{\text{K}}^{+}$ ATPase pump ($3{\text{ Na}}^{+}$ out, $2{\text{ K}}^{+}$ in).

Triggered when membrane potential reaches threshold (approx. $-55\text{ mV}$), causing voltage-gated ${\text{Na}}^{+}$ channels to open rapidly. Driven by electrochemical gradients, ${\text{Na}}^{+}$ rushes into the cell, driving $V_m$ up to $+30\text{ mV}$.

Occurs when voltage-gated ${\text{Na}}^{+}$ channels inactivate and slow voltage-gated ${\text{K}}^{+}$ channels open. Efflux of ${\text{K}}^{+}$ out of the cell restores the negative internal charge.