neuron
a nerve cell; the basic building block of the nervous system.
brain
specialized group of nerve cells that controls & coordinates activities of the nervous system
cns
the portion of the vertebrate nervous system consisting of the brain and spinal cord
pns
subdivision of the nervous system that brings information to the cns
autonomic nerves
serves the internal organs of the body
nerve impulse
message that travels from the dendrites of a neuron to the axon
axon
long nerve fiber that conducts away from the cell body of the neuron
dendrite
the branching extensions of a neuron that receives messages and conducts impulses toward the cell body
schwann cell
large nucleated cells that form myelin around the axons of neurons
node of ranvier
small gap between myelinated segments where axonal membrane is exposed; increase speed of impulses
synapse
the space between two neurons through which neurotransmiters travel
receptor
recieves information about changes in the enviroment (stimuli)
effector
muscles or glands that respond to impulses
stimulus
something that causes a response
cell body
contains major concentration of the cytoplasm and the nucleus of the neuron
myelin
an electrically-insulating phospholipid (fat) layer that surrounds the axons of many neurons
reflex
A relatively simple, involuntary response to a stimulus.
resting potential
the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse
action potential
change in electrical potential that occurs between the inside and outside of a nerve or muscle fiber when it is stimulated
refractory period
the time after a neuron fires during which a stimulus will not evoke a response
saltatory conduction
transmission of an impulse by jumping
neurotransmitter
a chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential(impulse)
spinal cord
part of central nervous system, links brain to rest of body
cerebellum
responsible for balance and coordination, routine movement
cerebrum
the largest part of the brain, controls thinking, reasoning, and memory
corpus callosum
connects the hemispheres; found deep inside cerebrum; allows hemispheres to share information
pons
relay link between brain and spinal cord
medulla oblongata
Regulates ? heart rhythm, blood flow, breathing rate,etc.
endorphins
natural neurotransmitters linked to pain control
sclera
Tough, white outer layer of the eye
choroid coat
middle layer of the eye; contains blood vessels
retina
The light sensitive layer of the eye which is composed of receptors (rods and cones).
aqueous humor
anterior cavity of the eye filled with clear, watery fluid
vitreous humor
the clear colorless transparent jelly that fills the posterior chamber of the eyeball
nearsightedness
a condition in which nearby objects are seen more clearly than distant objects
farsightedness
condition in which vision for distant objects is better than for near objects
rods
rod-shaped receptor in the retina of the eye that is sensitive to dim light but not color
cones
Receptor cells in the retina that are sensitive to bright light and produce color vision.
pinna
visible part of the outer ear. It collects sound and directs it into the auditory canal
eardrum
the membrane that seperates the outer ear from the middle ear and that vibrates when sound waves strike it (tympanic membrane)
hammer
the bone attached to the eardrum
anvil
the bone between the hammer and the stirrup
stirrup
a tiny U shaped bone that passes vibrations from the anvil to the cochlea
oval window
membrane that covers opening between middle ear and inner ear
cochlea
a coiled tube that is found in the inner ear and that is essential to hearing
semicircular canal
3 loops of fluid filled tubes that that are attached to to the cochlea; maintains equilibrium
olfactory cells
sensitive nerve cells in nasal passages.
autonomic nervous system
The part of the nervous system that controls involuntary action and responses.
eustachian tubes
tube connecting ear to throat; helps to equalize pressure
Parkinson's Disease
a progressive disease that destroys brain cells and is identified by muscular tremors, slowing of movement, and partial facial paralysis
Alzheimer's Disease
a disease that results in the progressive loss of an individual's memory and mental capacity.
ALS
Lou Gherig's Disease" - progressive neurological disease in which the motor neurons degenerate to the point of total loss of motor function. The intelligence, memory, and personality is unaffected.
Multiple Sclerosis
disorder in which myelin is destroyed causing loss of motor activity