A&P Chapter 10 The Nervous System

Herpes zoster or shingles

Viral infection that affects the skin of a single dermatome. Adult chickenpox.

Myelin

White fatty substance found in the myelin sheath around some nerve fibers. Formed by Schwann cells that wrap around some axons outside the central nervous system.

Diencephalon

"Between" brain; parts of the brain between the cerebral hemispheres and the midbrain.

Enkephalins

Peptide chemical in the central nervous system that acts a a natural painkiller.

Receptors

Peripheral beginning of a sensory neuron's dendrite.

Hypothalamus

Portion of the floor and lateral wall of the third ventricle of the brain; located below the thalamus; maintains the body's water balance by secreting the ADH hormone for the endocrine system; maintains body temperature.

Gyri

Ridges in the cerebrum.

Symptoms of Parkinson disease

Symptoms include muscle rigidity and trembling of head and extremities, forward tilt of body, and shuffling manner of walking.

White matter

Tissue made up of nerve tracts covered with white myelin.

Oligodendrocyte

A cell that holds nerve fibers together and produces the fatty myelin sheath around axons in the CNS, that envelops nerve fibers located in the brain and spinal cord.

Parkinson disease

A chronic disease of the nervous system characterized by a set of signs that results from a deficiency of the neurotransmitter dopamine in certain regions of the brain that normally inhibit over stimulation of skeletal muscles.

Cerebrovascular accident (CVA)

A hemorrhage or cessation of blood flow through cerebral blood vessels resulting in destruction of neurons; commonly called a stroke.

Serotonin

A neurotrasmitter that belongs to a group of compounds called catecholamines.

Ganglion

A region of unmyelinated nerve tissue (usually this term is used only for regions in the PNS)

Alzheimer Disease

Brain disorder of the middle and late adult years characterized by loss of memory and dementia.

Corpus callosum

Brain structure at which the right and left cerebral hemispheres are joined.

Dendrites

Branching or treelike; a nerve cell process that transmits impulses toward the body.

Epilepsy

A seizure disorder characterized by recurring seizures.

Astrocytes

A star shaped neuroglia cell; threadlike branches attach to neurons and to small blood vessels holding these structures close to each other.

Cerebral cortex

A thin layer of gray matter made up of neuron dendrites and cell bodies that compose the surface of the cerebrum.

Epineurium

A tough fibrous sheath that covers the whole nerve.

Hydrocephalus

Abnormal accumulation of cerebrospinal fluid; "water on the brain"

Cerebral palsy

Abnormal condition characterized by permanent, non-progressive paralysis of one or more extremities caused by damage to motor control areas of the brain before, during and shortly after birth.

Epinephrine

Adrenaline; hormone secreted by the adrenal medulla.

Reflex arc

Allows an impulse to travel in only one direction; a basic type of neuron pathway. Simplest kind of this is a two-neuron arc.

Tracts

Bundles of axons in the CNS; form white matter of the brain and cord.

Myleinated fibers

Axons outside the central nervous system that are surrounded by a segmented wrapping of myelin.

Catecholamines

Category of signaling molecule that includes norepinephrine and epinephrine; play a role in sleep, motor function, mood, and pleasure recognition.

Three parts to a Neuron

Cell body, dendrites, axon.

Endorphins

Chemical in the central nervous system that influences pain perception; a natural painkiller.

Dopamine

Chemical neurotransmitter. A deficiency in this causes Parkinson disease.

Neurotransmitters

Chemicals by which neurons communicate.

Perineurium

Connective tissue that encircles a bundle (fascicle) of nerve fibers within a nerve.

Huntington Disease

Degenerative, inherited brain disorder characterized by chorea (purposeless movements) progressing to severe dementia and death by age 55.

Arachnoid mater

Delicate, weblike middle membrane covering the brain, the meninges.

Autonomic neurons

Division of the human nervous system that regulates involuntary actions.

Cerebrospinal fluid

Fluid that fills the subarachnoid space in the brain and spinal cord and in the cerebral ventricles.

Meninges

Fluid-containing membranes surrounding the brain and spinal cord; contains pia mater, dura pater, arachnoid mater.

Neuroma

General term for nervous tissue tumors.

Neuritis

General term referring to nerve inflammation.

Neuralgia

General term referring to nerve pain.

Electroencephalogram (EEG)

Graphic representation of voltage changes in brain tissue used to evaluate nerve tissue function.

Sulci

Grooves in the cerebrum.

Nerve

Group of peripheral nerve fibers (axons) bundles together like strands of a cable, usually have a myelin sheath and often look white.

Antidiuretic hormone

Hormone produces in the posterior pituitary gland to regulate the balance of water in the body by accelerating the reapsorption of water.

Norepinephrine

Hormone secreted by adrenal medulla; released by sympathetic nervous system.

Sympathetic nervous system

Part of the autonomic nervous system; ganglia are connected to the thoracic and lumbar regions of the spinal cord; functions as an emergency system. "fight or flight response"

Nodes of Ranvier

Indentations found between adjacent Schwann cells.

Meningitis

Inflammation of the meninges caused by a variety of factors including bacterial infection, mycosis, viral infection, and tumors.

Multiple Neurofibromatosis

Inherited disease characterized by multiple, sometimes disfiguring, benign tumors of the Schwann cells that surround nerve fibers.

Reflex

Involuntary action. Response to impulse conduction over a reflex arc.

Structure of Spinal cord

It lies inside the spinal column in the spinal cavity and extends from the occipital bone down to the bottom of the first lumbar vertebra.

Synapse

Junction between adjacent neurons; nerve impulses stop here and chemical signals are sent along the dendrites, cell body and axon of motor neurons.

Schwann Cells

Large neucleated cells that form the myelin.

Dura mater

Literally "strong or hard mother"; outermost layer of the meninges.

Thalamus

Located just above the hypothalamus; its functions are to help produce sensations, associate sensations with emotions, and play a part in arousal mechanism.

Medulla oblongata

Lowest part of the brainstem. An enlarged extension of the spinal cord; the vital centers are located within this area.

Neuroblastoma

Malignant tumor of sympathetic nervous tissue, found mainly in young children.

Axons

Nerve cell process that transmits impulses away from the cell body; have no neurilemma and therefore regeneration is unlikely.

Neurons

Nerve cell, including its processes (axons and dendrites). Conducts impulses.

Action potentials

Nerve impulse.

Interneurons

Nerve that conducts impulses from a sensory neuron to a motor neuron. Central or connecting neurons.

Sciatica

Neuralgia (pain)of the sciatic nerve.

Glia

Neuroglia. Do not specialize in transmitting impulses, instead they are supporting cells of nervous tissue; hold neurons together and protect them.

Motor Neurons

Neuron that transmits nerve impulses from the brain and spinal cord to muscles and glandular epithelial tissue. Efferent neurons.

Sensory Neurons

Neurons that transmit impulses to the spinal cord and brain from all parts of the body. Afferent neurons.

Glioma

One of the most common types of brain tumors.

Midbrain

One of the three parts of the brainstem; Superior part of the brainstem.

Microglia

One type of connective tissue found in the brain and spinal cord. Smaller than astrocytes. Digest microbes when they are inflammed.

Hemiplegia

Paralysis (lack of voluntary muscle control) of one entire side of the body.

Quadriplegia

Paralysis in all four limbs.

Parasympathetic nervous system

Part of the autonomic nervous system; ganglia are connected to the brainstem and the sacral segments of the spinal cord; controls many visceral effectors under normal conditions.

Three types of Neurons

Sensory, Motor, and Interneurons.

Fascicles

Small bundle of fibers, as in a small bundle of nerve fibers or muscle fibers.

Seizures

Sudden onset of abnormal body function, as in a brain seizure when a sudden disruption in the normal firing of neurons in the brain causes mild to severe neurological symptoms such as involuntary muscle spasms, changes in consciousness, or abnormal sensations.

Dementia

Syndrome of brain abnormalities that include loss of memory, shortened attention span, personality changes, reduced intellectual capacity, and motor dysfunction.

Bell palsy

Temporary or permanent paralysis of facial features caused by damage to cranial nerve VII. (facial nerve)

Cerebrum

The largest and uppermost part of the human brain that controls consciousness, memory, sensations, emotions, and voluntary movements. Has many ridges and grooves.

Cell body

The main part of a neuron from which the dendrites and axons extend.

Multiple Sclerosis

The most common primary disease of the central nervous system; a myelin disorder. Characterized by myelin loss and destruction accompanied by varying degrees of oligodendrocyte injury and death. Most common in women between ages 20 & 40.

Neurilemma

The outer layer of the Schwann cell.

Pons

The part of the brainstem between the medulla oblongata and the midbrain; consists of gray and white matter.

Cerebellum

The second largest part of the human brain that plays an essential role in the production of normal movements; lies just below the occipital lobe of the cerebrum and responsible for muscle coordination.

Endoneurium

The thin wrapping of fibrous connective tissue that surrounds each axon in a nerve.

Pia mater

The vascular innermost covering of the brain and spinal cord.

Gray matter

Tissue in the central nervous system made up of cell bodies and unmyelinated axons and dendrites; gray in color.