human neurons

In 1937, John Zachary Young suggested that the squid giant axon could be used to study neuronal electrical properties. Being larger  human neurons than but similar in nature to human neurons , squid cells were easier to study.  human neurons By inserting electrodes into the giant squid axons, accurate measurements  human neurons  were made of the membrane potential. human neurons The cell membrane of the axon and soma contain voltage-gated ion channels that allow human neurons  the neuron to generate and propagate an electrical signal (an action potential). human neurons  These signals are generated and propagated by charge-carrying ions including sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+).

There are several stimuli that can activate a neuron leading to electrical activity, including pressure, stretch, chemical transmitters, and changes of the electric potential across the cell membrane. Stimuli cause specific ion-channels within the cell membrane to open, leading to a flow of ions through the cell membrane, changing the membrane potential.

Thin neurons and axons require less metabolic expense to produce and carry action potentials, but thicker axons human neurons  convey impulses more rapidly. To minimize metabolic expense while maintaining rapid conduction, many neurons have insulating sheaths of myelin around their axons. The sheaths are formed by glial cells: oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. The sheath enables action potentials to travel faster than in unmyelinated axons of the same diameter, whilst using less energy. human neurons The myelin sheath in peripheral nerves normally runs along the axon in sections about 1 mm long, punctuated by unsheathed nodes of Ranvier, which contain a high density of voltage-gated ion channels. Multiple sclerosis is a neurological disorder that results from demyelination of axons in the central nervous system.

Some neurons do not generate action potentials, but instead generate a graded electrical signal, which in turn causes graded neurotransmitter release. human neurons  Such nonspiking neurons tend to be sensory neurons or interneurons, because they cannot carry signals long distances.