Chapter 3

Front 1

Central Nervous System (CNS)

Back 1

The portion of the nervous system within the skull and spine.

Front 2

Peripheral Nervous System (PNS)

Back 2

The portion of the nervous system outside the skull and spine.

Front 3

Somatic Nervous System (SNS)

Back 3

The part of the peripheral nervous system that interacts with the external environment.

Front 4

Afferent Nerves

Back 4

Nerves that carry sensory signals to the central nervous system; sensory nerves.

Front 5

Efferent Nerves

Back 5

Nerves that carry motor signals from the central nervous system to the skeletal muscles or internal organs.

Front 6

Autonomic Nervous System (ANS)

Back 6

The part of the peripheral nervous system that participates in the regulation of the body's internal environment.

Front 7

Sympathetic Nerves

Back 7

Those motor nerves of the autonomic nervous system that project from the CNS in the lumbar and thoracic areas of the spinal cord.

Front 8

Parasympathetic Nerves

Back 8

Those motor nerves of the autonomic nervous system that project from the brain (as components of cranial nerves) or from the sacral region of the spinal cord.

Front 9

Cranial Nerves

Back 9

The 12 pairs of nerves extending from the brain (e.g., the optic nerves, the olfactory nerves, and the vagus nerves).

Front 10

Meninges

Back 10

The three protective membranes that cover the brain and spinal cord (singular meninx).

Front 11

Dura Mater

Back 11

The tough outer meninx.

Front 12

Arachnoid Membrane

Back 12

The meninx that is located between the dura mater and the pia mater and has the appearance of a gauzelike spiderweb.

Front 13

Subarachnoid Space

Back 13

The space beneath the arachnoid membrane, which contains many large blood vessels and cerebrospinal fluid.

Front 14

Pia Mater

Back 14

The delicate, innermost meninx.

Front 15

Cerebrospinal Fluid (CSF)

Back 15

The colorless fluid that fills the subarachnoid space, the central canal, and the cerebral ventricles.

Front 16

Central Canal

Back 16

The small CSF-filled channel that runs the length of the spinal cord.

Front 17

Cerebral Ventricles

Back 17

The four CSF-filled internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle.

Front 18

Choroid Plexuses

Back 18

The networks of capillaries that protrude into the ventricles from the pia mater and continuously produce cerebrospinal fluid.

Front 19

Blood-Brain Barrier

Back 19

The mechanism that keeps certain toxic substances in the blood from passing into the brain tissue.

Front 20

Neurons

Back 20

Cells of the nervous system that are specialized for the reception, conduction, and transmission of electrochemical signals.

Front 21

Multipolar Neuron

Back 21

A neuron with more than two processes extending from its cell body.

Front 22

Unipolar Neuron

Back 22

A neuron with one process extending from its cell body.

Front 23

Bipolar Neuron

Back 23

A neuron with two processes extending from its cell body.

Front 24

Interneurons

Back 24

Neurons with short axons or no axons at all, whose function is to integrate neural activity within a single brain structure.

Front 25

Nuclei

Back 25

Clusters of neuronal cell bodies in the central nervous system (singular nucleus)

Front 26

Ganglia

Back 26

Clusters of neuronal cell bodies in the peripheral nervous system (singular ganglion).

Front 27

Tracts

Back 27

Bundles of axons in the central nervous system.

Front 28

Nerves

Back 28

Bundles of axons in the peripheral nervous system.

Front 29

Glial Cells

Back 29

Several classes of nonneural cells of the nervous system, whose important contributions to nervous system function are just starting to be understood.

Front 30

Oligodendrocytes

Back 30

Glial cells that myelinate axons of the central nervous system; also called oligodendroglia.

Front 31

Myelin

Back 31

A fatty insulating substance found in the extensions of glial cells.

Front 32

Myelin Sheaths

Back 32

Coverings on the axons of some CNS neurons that are rich in myelin and increase the speed and efficiency of axonal conduction.

Front 33

Schwann Cells

Back 33

The glial cells that compose the myelin sheaths of PNS axons and promote their regeneration.

Front 34

Microglia

Back 34

Glial cells that respond to injury or disease by engulfing cellular debris and triggering inflammatory responses.

Front 35

Astrocytes

Back 35

Large, star-shaped glial cells that play a role in the passage of chemicals from the blood into CNS neurons and perform several other important functions that are not yet well understood.

Front 36

Golgi Stain

Back 36

A neural stain that completely darkens a few of the neurons in each slice of tissue, thereby revealing their silhouettes.

Front 37

Nissl Stain

Back 37

A neural stain that has an affinity for structures in neuron cell bodies.

Front 38

Electron Microscopy

Back 38

A neuroanatomical technique used to study the fine details of cellular structure.

Front 39

Anterior

Back 39

Toward the nose end of the vertebrate.

Front 40

Posterior

Back 40

Toward the tail end of a vertebrate or toward the back of the head.

Front 41

Dorsal

Back 41

Toward the surface of the back of a vertebrate or toward the top of the head.

Front 42

Ventral

Back 42

Toward the chest surface of a vertebrate or toward the bottom of the head.

Front 43

Medial

Back 43

Toward the midline of the body of a vertebrate.

Front 44

Lateral

Back 44

Away from the midline of the body of a vertebrate, toward the body's lateral surfaces.

Front 45

Superior

Back 45

Toward the top of the primate head.

Front 46

Inferior

Back 46

Toward the bottom of the primate head or brain.

Front 47

Proximal

Back 47

Nearer the central core of the body (e.g., the elbows are proximal to the wrists).

Front 48

Distal

Back 48

Farther from the central core of the body (e.g., the wrists are distal to the elbows).

Front 49

Horizontal Sections

Back 49

Any slices of brain tissue cut in a plane that is parallel to the top of the brain.

Front 50

Frontal Sections

Back 50

Any slices of brain tissue cut in a plane that is parallel to the face; also termed coronal sections.

Front 51

Sagittal Sections

Back 51

Any slices of brain tissue cut in a plane that is parallel to the side of the brain.

Front 52

Cross Section

Back 52

Section cut at a right angle to any long, narrow structure of the CNS.

Front 53

Gray Matter

Back 53

Portions of the nervous system that are gray because they are composed largely of neural cell bodies and unmyelinated interneurons.

Front 54

White Matter

Back 54

Portions of the nervous system that are white because they are composed largely of myelinated axons.

Front 55

Dorsal Horns

Back 55

The two dorsal arms of the spinal gray matter.

Front 56

Ventral Horns

Back 56

The two ventral arms of the spinal gray matter.

Front 57

Dorsal Root Ganglia

Back 57

Structures just outside the spinal cord that are composed of the cell bodies of dorsal root axons.

Front 58

Brain Stem

Back 58

The part of the brain on which the cerebral hemispheres rest; in general, it regulates reflex activities that are critical for survival (e.g., heart rate and respiration).

Front 59

Sensory Relay Nuclei

Back 59

Those nuclei of the thalamus whose main function is to relay sensory signals to the appropriate areas of cortex.

Front 60

Decussate

Back 60

To cross over to the other side of the brain.

Front 61

Contralateral

Back 61

Projecting from one side of the body to the other.

Front 62

Ipsilateral

Back 62

On the same side of the body.

Front 63

Sulci

Back 63

Small furrows in a convoluted cortex.

Front 64

Pyramidal Cells

Back 64

Large multipolar cortical neurons with a pyramid-shaped cell body, an apical dendrite, and a very long axon.

Front 65

Stellate Cells

Back 65

Small star-shaped cortical interneurons.

Front 66

Columnar Organization

Back 66

The functional organization of the neocortex in vertical columns; the cells in each column form a mini-circuit that performs a single function.