axon

Examples of axon in the following topics:

• Introducing the Neuron

  • The cell body contains a specialized structure, the axon hillock, which serves as a junction between the cell body and the axon.
  • One neuron's axon will connect chemically to another neuron's dendrite at the synapse between them.
  • to neurons with very long axons that travel up the spine to the brain.
  • Some axons are covered with myelin, a fatty material that wraps around the axon to form the myelin sheath.
  • At these nodes, the signal is "recharged" as it travels along the axon.

• Neural Networks

  • If a stimulus creates a strong enough input signal in a nerve cell, the neuron sends an action potential and transmits this signal along its axon.
  • The axon of a nerve cell is responsible for transmitting information over a relatively long distance, and so most neural pathways are made up of axons.
  • For example, motor neurons, which travel from the spinal cord to the muscle, can have axons up to a meter in length in humans.
  • The longest axon in the human body is almost two meters long in tall individuals and runs from the big toe to the medulla oblongata of the brain stem.
  • Neurons interact with other neurons by sending a signal, or impulse, along their axon and across a synapse to the dendrites of a neighboring neuron.

• Stages of the Action Potential

  • In unmyelinated axons (axons that are not covered by a myelin sheath), this happens in a continuous fashion because there are voltage-gated channels throughout the membrane.
  • In myelinated axons (axons covered by a myelin sheath), this process is described as saltatory because voltage-gated channels are only found at the nodes of Ranvier, and the electrical events seem to "jump" from one node to the next.
  • The diameter of the axon also makes a difference, as ions diffusing within the cell have less resistance in a wider space.

• Habituation, Sensitization, and Potentiation

  • In neural communication, a neurotransmitter is released from the axon of one neuron, crosses a synapse, and is then picked up by the dendrites of an adjacent neuron.
  • This image shows the way two neurons communicate by the release of the neurotransmitter from the axon, across the synapse, and into the dendrite of another neuron.
  • Communication between neurons occurs when the neurotransmitter is released from the axon on one neuron, travels across the synapse, and is taken in by the dendrite on an adjacent neuron.

• Neuroplasticity

  • "Synaptic (or neuronal or axon) pruning" refers to neurological regulatory processes that facilitate changes in neural structure by reducing the overall number of neurons and synapses, leaving more efficient synaptic configurations.
  • Pruning removes axons from synaptic connections that are not functionally appropriate.

• Cerebral Cortex

  • Gray matter is the mass of all the cell bodies, dendrites, and synapses of neurons interlaced with one another, while white matter consists of the long, myelin-coated axons of those neurons connecting masses of gray matter to each other.

• Neurotransmitters

  • When the chemical message reaches the axon terminal, channels in the postsynaptic cell membrane open up to receive neurotransmitters from vesicles in the presynaptic cell.

• Mechanics of the Action Potential

  • Presynaptic cell: a specialized area within the axon of the giving cell that transmits information to the dendrite of the receiving cell.