Nervous System Subdivisions, Neuron Properties, and Axonal Regeneration

Vocabulary flashcards covering the subdivisions of the nervous system, universal properties and functional classes of neurons, and the detailed mechanisms and requirements of peripheral axonal regeneration.

Motor (efferent) division

The division of the nervous system that sends signals from the CNS to a gland or muscle (effectors) to create a response.

Somatic motor division

The subdivision of the motor division that carries signals to skeletal muscles, governing both voluntary and involuntary muscle contractions.

Visceral motor division (Autonomic Nervous System)

The subdivision of the motor division consisting of sensory neurons that carry information from autonomic sensory receptors to the CNS, and motor neurons that convey signals from the CNS to smooth muscle, cardiac muscle, and glands to conduct involuntary action.

Sympathetic division

A division of the autonomic nervous system responsible for the 'fight or flight' response, such as increasing heart rate.

Parasympathetic division

A division of the autonomic nervous system responsible for 'rest and digest' activity, such as slowing heart rate.

Neurons

Nerve cells that receive stimuli and convert information into an action potential.

Excitability

A universal property of neurons referring to the ability of cells to respond to environmental changes (stimuli).

Conductivity

A universal property of neurons where they respond to stimuli by producing electrical signals that are sent out to other cells.

Secretion

A universal property of neurons wherein chemical neurotransmitters are secreted at the end of the nerve in response to a signal, crossing a gap to stimulate another cell.

Sensory (afferent) neuron

A type of unipolar neuron that contains sensory receptors or is adjacent to one, functioning to send action potentials into the CNS through cranial or spinal nerves.

Regeneration tube

A structural channel formed by Schwann cells, basal lamina, and neurilemma following peripheral axon injury that enables a neuron to grow to its original destination and reestablish synaptic contact.

Endoneurium

The connective tissue layer surrounding the myelin sheath that, alongside Schwann cells, is required for peripheral nerve repair.

CNS Regeneration Absence

The inability of the central nervous system to regenerate at all due to the complete lack of both Schwann cells and endoneurium.

Structural Changes in Injured Cell Body

The process where loss of nerve growth factors from a neuron's target cell following axon severance causes the ER to break up and the nucleus to move off-center.

Reestablishment of Synaptic Contact

The final phase of peripheral nerve repair when contact with the original target is reestablished, causing the cell body to shrink, the nucleus to return to normal shape, growth processes to retract, and atrophied muscle fibers to regrow.