1: Neurons and Synapses

Neurons and Synapses

Your brain contains about 86 billion neurons—specialized cells that process and transmit information. Think of them as biological wiring, sending messages to control everything from breathing to solving puzzles. Each neuron has three key parts:

1. Dendrites: Branch-like structures that receive signals from other neurons.
2. Cell Body (Soma): The neuron’s core, where incoming signals are combined.
3. Axon: A long "cable" that sends electrical impulses away from the cell body.

Neurons communicate through a two-step process: electrical signals travel within a neuron, and chemical signals jump between neurons.

Step 1: Electrical Signaling (The Action Potential)

When dendrites receive enough stimulation, an electrical wave—called an action potential—zips down the axon like a pulse of electricity. This impulse moves quickly because axons are insulated by a fatty layer called myelin. Myelin acts like rubber coating on a wire, speeding up signals.

Step 2: Chemical Signaling (The Synapse)

At the axon’s end, the electrical signal reaches a synapse—a tiny gap between neurons. Here, the message turns chemical:

• The sending neuron releases neurotransmitters (chemical messengers) into the synapse.
• These neurotransmitters float across the gap and lock onto receptors on the receiving neuron’s dendrites.
• If enough receptors are activated, the receiving neuron fires its own electrical impulse.

Key Players: Neurotransmitters

Different neurotransmitters trigger distinct effects:

• Glutamate excites neurons (e.g., boosts learning).
• GABA calms them (e.g., reduces anxiety).
• Dopamine drives reward and motivation.
  After delivery, neurotransmitters are either reabsorbed by the sender or broken down, resetting the synapse for the next signal.

Why Synapses Matter

Synapses aren’t static; they strengthen or weaken with use—a feature called plasticity. Repeated communication makes synapses more efficient, helping you form memories or learn skills. Conversely, unused connections fade. This adaptability lets your brain rewire itself throughout life.

Neurons and synapses form a dynamic network where electrical bursts and chemical whispers create thoughts, emotions, and actions—all in milliseconds.