Nervous System Divisions and Glial Cells

Vocabulary flashcards covering the structural and functional divisions of the nervous system and the types and functions of central and peripheral glial cells.

Sensory (afferent) division

Carries signals from various receptors (sense organs and simple sensory nerve endings) to the CNS, informing the CNS of stimuli within and around the body.

Somatic sensory division

Carries signals from receptors located in the skin, muscles, bones, and joints.

Visceral sensory division

Carries signals mainly from the viscera of the thoracic and abdominal cavities, such as the heart, lungs, stomach, and urinary bladder.

Motor (efferent) division

Carries signals from the CNS mainly to gland and muscle cells that carry out the body's responses.

Effectors

Cells and organs that respond to signals from the motor division to carry out the body's responses.

Somatic motor division

Carries signals to the skeletal muscles, producing voluntary muscle contractions as well as automatic reflexes.

Visceral motor division (Autonomic nervous system, ANS)

Carries signals to glands, cardiac muscle, and smooth muscle; operates at an unconscious level without voluntary control.

Visceral reflexes

The unconscious responses executed by the autonomic nervous system (ANS) and its effectors.

Sympathetic division

A division of the ANS that tends to arouse the body for action (such as accelerating the heartbeat and increasing respiratory airflow) while inhibiting digestion and reducing urine production.

Parasympathetic division

A division of the ANS that tends to have a calming effect (such as slowing the heartbeat) while stimulating digestion.

Enteric plexus

An extensive network lying in the wall of the digestive tract, composed of more neurons than the spinal cord, that coordinates digestive motility and secretion.

Oligodendrocytes

Central glial cells that form myelin in the brain and spinal cord.

Ependymal cells

Central glial cells that line cavities of the brain and spinal cord; secrete and circulate cerebrospinal fluid.

Microglia

Central glial cells that phagocytize and destroy microorganisms, foreign matter, and dead nervous tissue.

Astrocytes

Central glial cells that cover the brain surface and nonsynaptic regions of neurons; form a supportive framework; induce blood-brain barrier formation; nourish neurons; produce growth factors; promote synapse formation; communicate electrically; remove $K^+$ and neurotransmitters from ECF; regulate ECF composition; and form scar tissue.

Schwann cells

Peripheral glial cells that form the neurolemma around all PNS axons and myelin around most of them, and aid in the regeneration of damaged nerves.

Satellite cells

Peripheral glial cells that surround cell bodies of neurons in the ganglia, providing electrical insulation and regulating the chemical environment of neurons.