Chapter 7 Nervous System Vocabulary Words #1

Central nervous system

• the brain and the spinal cord.

Peripheral nervous system

• a system of nerves that connects the outlying parts of the body with the central nervous system.

Afferent nerves

• Nerves that carry impulses only toward the CNS; aka sensory nerves.

Efferent nerves

• Nerves that carry only motor fibers; aka motor nerves

Autonomic nervous system

• the division of the nervous system that functions involuntarily; innervates cardiac muscle, smooth muscle, and glands; also called involuntary nervous system.

Somatic nervous system

• a division of the peripheral nervous system; also called the voluntary nervous system.

Neuroglia

• the nonneuronal tissue of the central nervous system that performs supportive and other functions; also called glial cells or glia.

Astrocytes

• type of CNS supporting cell; assists in exchanges between blood capillaries and neurons.

Microglia

• type of CNS supporting cell; phagocytes that ingest debris such as bacteria or dead cells.

Ependymal cells

• type of CNS supporting cell; lines the central cavities of the brain and spinal cord and circulates cerebrospinal fluid with their beating cilia.

Oligodendrocytes

• type of CNS supporting cell that has many cellular processes, each of which makes up a myelin sheath.

Satellite cells

• type of neuroglia in the PNS; protects and cushions peripheral nerve cell bodies.

Schwann cells

• type of neuroglia in the PNS; many Schwann cells form the myelin sheath on a single neuron.

Dendrites

• the branching extensions of neurons that carry electrical signals to the cell body; the receptive portion of a nerve cell.

Axon

• neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell.

Nodes of ranvier

• Gaps or indentations between schwann cells.

Bipolar neurons

• Neurons with two processes—one axon and one dendrite-

Unipolar neurons

• structural class of neuron with one process extending from the cell body.

Multipolar neurons

• structural class of neuron with more than two processes extending from the cell body.

Neurotransmitters

• chemical released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit them.

Synapse

• the region of communication between neurons, or a neuromuscular junction between a neuron and a muscle cell.

Myelin sheath

• Encloses the axon and acts as an insulating layer.

Neurilemma

• The outer layers of the schwann cells. (“Neuron husk“)

Multiple sclerosis (MS)

• autoimmune disorder of the CNS where the myelin sheaths are converted into hardened scleroses in the brain and spinal cord; results in loss of control.

Ganglia

• Small collections of cell bodies found in a few sites outside the CNS in the PNS.

Gray matter

• the gray area of the central nervous system; contains unmyelinated nerve fibers and nerve cell bodies.

White matter

• white substance of the central nervous system; the myelinated nerve fibers.

Interneurons or association neurons

• completes the pathway between afferent and efferent neurons; also called an association neuron.

Cutaneous sense organs

• Sensory receptors in the skin

proprioceptors

• Sensory receptors in the muscles and tendons