Med. Term Ch. 10 The Nervous System - Nerves

Central nervous system

Nervous system subdivision that is composed of the brain and spinal cord.

Peripheral nervous system

Nerves outside the brain and spinal cord; cranial, spinal and autonomic nerves.

Autonomic nervous system

Nerves that control the involuntary body functions of muscles, glands and organs.

Neuroglia

Support, insulate, and protect cells.

Axon

microscopic fiber that carries the nervous impulse along a nerve cell.

Dendrite

microscopic branching fiber of a nerve cell that is the first part to receive the nervous impulse.

Myelin sheath

Covering of white, fatty tissue that surrounds and insulates the axon of a nerve cell. Myelin speeds impulse conduction along axons.

Cell body

Part of the nerve cell that contains the nucleus.

Synapse

Space through which a nervous impulse travels between nerve cells or between nerve and muscle or glandular cells.

Ganglia

Collection of nerve cell bodies found in the peripheral nervous system

Efferent nerve

Nerve that carries messages away from the CNS; motor nerve

Afferent nerve

Nerve that conducts impulses toward the CNS from the body periphery.

Stimuli

Agent of change (light, sound touch), occurring within or outside the body, that affect nervous system functioning.

Neurotransmitters

Chemicals messengers released by nerves at the end of the nerve cell that stimulate other neurons, muscles, or glands (ex: acetylcholine, norepinephrine, dopamine, seratonin)

acetylcholine

neurotransmitter released at the ends of nerve cell

astrocyte

type of glial (neuroglial) cell that transports water and salts from capillaries

Blood-brain barrier

blood vessels that selectively let certain substances enter the brain tissue and keep other substances out.

Cranial nerves

twelve pairs of nerves that carry messages to and from the brain with regard to the head and neck (except the vagus nerve)

Vagus nerve

Tenth cranial nerve; its branches reach to the larynx, trachea, bronchi, lungs, aorta, esophagus and stomach. Only cranial nerve that leaves the head.

Ependymal cell

Glial cell that lines membranes within the brain and spinal cord and helps form cerebrospinal fluid.

glial cell (neurological cell)

supportive and connective nerve cell that does not carry nervous impulses (astrocytes, microglial cells, ependymal cells and oligodendrocytes).

microglial cell

Phagocytic cell that removes waste products from the CNS

motor nerve

carries messages away from the brain and spinal cord to muscles and organs: efferent nerve.

nerve

macroscopic cord-like collection of fibers (axons and dendrites) that carry electrical impulses.

neuron

nerve cell that carries impulses throughout the body

oligodendroglial cell

Glial cell that forms the myelin sheath covering axons.

Parasympathetic nerve

Involuntary, autonomic nerves that regulate normal body functions such as heart rate, breathing and muscles of the GI tract

Parenchyma

Essential distinguishing tissue of any organ or system. The parenchyma of the nervous system are brain, spinal cord and neurons.

Plexus

large, interfacing network of nerves (lumbosacral, cervical, brachial)

Receptor

Organ that receives a nervous stimulus and passes it on to afferent nerves (ex. skin, ears, eyes, taste buds).

Sciatic Nerve

nerve extending from the base of the spine down through the thigh, lower leg and foot.

Sensory nerve

carries message towards the brain and spinal cord from a receptor (afferent nerve)

Spinal nerves

31 pairs of nerves arising from the spinal cord

Stroma

Connective and supporting tissue of an organ. Glial cells are the stromal tissue of the brain.

Sympathetic nerve

autonomic nerves that influence bodily functions involuntarily in times of stress.