Neurons and Synaptic Transmission

Neuron

The basic building block of the nervous system that processes and transmits messages through electrical and chemical signals.

Sensory neuron

A nerve cell that carries messages from the peripheral nervous system (PNS) to the central nervous system (CNS)

Relay neuron

A nerve cell within the CNS that connects sensory neurons to motor or other relay neurons

Motor neuron

A nerve cell that connects the CNS to effectors like muscles and glands

Cell body (Soma)

The core part of a neuron containing the nucleus with genetic material.

Dendrite

Branchlike structure at the receiving end of a neuron that collects chemical signals from neighboring neurons.

Axon

The long extension of a neuron that carries electrical impulses away from the cell body toward the terminal boutons.

Myelin sheath

A fatty layer surrounding and protecting the axon to prevent signal loss.

Nodes of Ranvier

Gaps in the myelin sheath that speed up electrical impulse transmission by forcing the signal to jump across segments.

Terminal bouton

Structure at the end of an axon that converts electrical impulses into chemical signals released into the synapse.

Synaptic transmission

The process by which neighbouring neurons communicate by releasing chemical messages across the synaptic gap.

Synaptic vesicle

Tiny sac inside the presynaptic terminal bouton that stores and releases neurotransmitters into the synapse.

Neurotransmitter

Brain chemicals that relay signals across the synapse by binding to specific receptor sites on the postsynaptic neuron.

Excitation

When a neurotransmitter (e.g.

Inhibition

When a neurotransmitter (e.g.

Summation

The process by which the postsynaptic neuron combines all incoming excitatory and inhibitory signals to determine whether an action potential will fire.