chapter 9

transmit nerve impulses along nerve fibers to other neurons .

neurons

have a cell body, axons and dendrites

neurons

made up of bundles of nerve fibers

nerves

carry out a variety of functions to aid and protect components of the nervous system

neuroglia

nervous system can be divded into the ______ made of the brain and spinal cord.

central nervous system(cns)

made up of peripheral nerves that conect the cns to the rest of the body

peripheral nervous system (pns)

provides sensory, interagtive, and motor functions to the body

nervous system

motor functions can be divded into the consicously controlled_____ ___ and the ___ _____

somatic nervous system unconscious autonomic system

gather information and convert into nerve impulses

sensory receptors

when sensory impulses are intergrated in as perceptions, this is the intergrative function of the

nervous system

conscious or subconscious decisions follow, leading to

motor functions via effectors

fill spaces, support neurons provide structural frameworks produce myelin and carry on phagocytosis

neuroglial cells

small cells that phagoctyize bacterial cells and cellular debris

microglial cells

form myelin in the brain and spinal cord

oligodendrocytes

near blood vessels and support structures aid in metabolism, and respond to brain injury by filling in spaces.

astrocytes

cover the inside of ventricles and form choroid plexuses within ventricles

ependyma

myelin producing neuroglia of the peripheal nervous system

schwann

cell body with mitchodria, lysosomes, a golgi apparatus, chromatophilic substance contaning rough endoplasmic reticulum and neurofibrils

neuron structure

cary impulses from other neurons toward cell body

branching dendrites

transmitts the impulse away from the axonal hillock of the cell body and may give off side branches

axon

larger axons are enclosed by sheaths of myelin provided by

schwann cells

the outer layer of myelin is surrounded by a neurilemma made up of the ______ and ____ of the schwann cell

cytoplasm, nuclei

narrow gaps in the myelin sheath between schwann cells are called

nodes of ranvier

the smallest axons lack a _____ _____ and are unnyelinated fibers

myelin sheath

_______ in the cns is due to myelin sheaths in this area

white matter

unmyelinated nerve tissue in the cns comprise the ___ ____

gray matter

bipolar unipolar and multipolar neurons

structural differences

sensory neurons interneurons and motor neurons

functional differences

found in the eyes, nose, and ears, and have a single axaon and a single dendrite extending from opposite sides of the cell body.

bipolar neurons

found in ganglia outside the cns and have an axon and a dendrite arising from a single short fiber extending from the cell

unipolar neurons

have many nerve fibers arising from their cell bodies and are commonly found in the brain and spinal cord

multipolar neurons

conduct impulses from peripheral receptors to the cns and are usually unipolar, although some are bipolar neurons

sensory neurons

are mulitpolar nerons lying within the cns that form links between other neurons

interneurons

are mulitpolar neurons hat conduct impulses from cns to effectors

motor neurons

a cell membrane is usually...

polarized

___ is important to the conduction of nerve impulses

polarization

the distribution of ions is determined by the....

membrane chanel proteins

______ ______ is a major contributor to membrane polarization

potassium ions

maintains a greater concetration of __ ___ outside and a greater concentrion of ___ __ inside tht membrane.(active transport)

sodium ions, potassium ions

the inside of the membrane has excess ___ charges, while the outside has more ____ charges

negative, postive

seperation of charge, or potential difference, is called the

resting potential

___________ of membrane can locally affect its resting potential.

stimulation

when the membrane potential becomes less negative, the membrane is

depolarized

if sufficiently strong depolarization occurs a ___ ___ is achieved as ion channels open

thershold potential

an action potential is reached

at threshold

may be reached when a series of subthreshold stimuli summate and reach threshold

action potenials