Test One Flashcards
neurophysiology
the study of how the nervous system functions
neuron
cell that does work in nervous system
semi permeable
allows some ions to pass through and excludes other ions almost exclusively
ION
single atoms of chemical elements which have too many or too few electrons
action potential
basic mechanism by which neurons carry information over distances
About how many neurons are estimated to be in the CNS?
10 billion
what two main structures are neurons composed of?
cell body and neurites
What are neurites made of?
dendrite and axon
bipolar neurons are found where?
cochlear and retina
dendrites conduct impulses ___ the soma
toward
axons conduct impulses ___ from the soma
away
Most common type of neuron
multipolar
afferent conduct
toward
efferent conduct
away
what is the function of association neurons?
communication between neurons and conduct impulses
another name for association neurons
internuncial neurons or interneurons
resting membrane potential
electrical difference across cell membrane
volt range of RMP
-60 to -80 mV
active transport
process in which a cell membrane moves ions against a concentration gradient
excitation threshold
cell membrane must be depolarized to a critical level to produce action potential
all or nothing law
any threshold stimulus produces a full size action potential and a less than threshold stimulus produces no action potential
conduction velocity affects
myelin and the diameter of the axon
1 to 2 mm along its length interruption
node of Ranvier
myelin sheath within
oligodendrocytes
myelin sheath outside
schwann cells
first suspected the electrical nature
Galvani
propagation in relation to action potentials
signal goes cell to cell along nerve pathway
absolute refractory period
when cell is firing (producing spike) cell unresponsive to stimulus
relative refractory
during repolarization and hyperpolarization larger stimuls needed
nobel prize 1963
Hodgkin and huxley
irritable cells
capable of being stimulated
