Week 1: Action Potential Flashcards
Membrane
surrounds the cell
nucleus
The structure that contains the cell’s genetic material in the form of DNA
mitochondrion
the structure that performs metabolic activities
ribosomes
protein synthesis
motor neurons
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
sensory neuron
neurons that carry incoming information from the sensory receptors to the brain and spinal cord
dendrites
branch-like parts of a neuron that are specialized to receive information
dendritic spines
short outgrowths that increase the surface area available for synapses
axon
the neuron extension that passes messages through its branches to other neurons or to muscles or glands
cell body
contains nucleus
myelin sheath
insulating membrane surrounding the axon in some neurons
presynaptic terminal
insulating membrane surrounding the axon in some neurons
afferent axon
brins information into a structure
efferent structure
carries information away from a structure
glia
cells found throughout the nervous system that provides various types of support for neurons
astrocytes
Star-shaped glia that synchronize the activity of the axons
microglia
act as phagocytes, eating damaged cells and bacteria, act as the brain’s immune system
Oligodendrocytes
for myelin sheath in CNS
radial glia
guide the migration of neurons and their axons and dendrites during embryonic development
blood-brain barrier
blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out
polarization
difference in electrical charge between the inside and outside of the cell
selective permeability
some substances cross a membrane more easily than other substances do
sodium potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium intos into the cell
concentration gradient
difference in the concentration of a substance across a distance
depolarize
reduce its polarization toward zero
threshold
the level of stimulation required to trigger a neural impulse
action potential
messages sent by axons
hyperpolarization
movement of the membrane potential of a cell away from the resting potential in a more negative direction.
all or none law
principle that the action potetnial ina. neuron does not vary in strength: the neuron either fires at full strength or it does not fire at all
propagation of the action potential
transmission of an action potential down an axon
voltage-gated channels
open and close in response to changes in membrane potential
refractory period
A period of inactivity after a neuron has fired
absolute refractory period
the membrane cannot produce an actional potential, regardless of the stimulation
relative refractory period
a stronger than usual stimulus is necessary to initiate an action potential
local neurons
neurons without an axon
graded potential
A membrane potential that varies in magnitude in proportion to the intensity of the stimulus
resting potential
- membrane is not very permeable to NA, but there is a continuous influx through the membrane, counterbalanced by NA/K pump
how permeable is the membrane to potassium
the membrane is 100 x more permeable to K
stage 1
- electrical signal (incoming) triggers an A.P when it reaches the threshold of excitation
- triggered by depolarization, NA channels open
stage 2
triggered by an even greater level of depolarization, K channels open, causing K+ outflux
stage 3
bc of the rapid influx of NA, membrane potential changes from -70mv to +40 mv
- triggers sodium channels to become refractory (close and cannot open again until the membrane once more reaches the resting potential)
stage 4
- inside, the axis is + charged, which causes an outflux of K
- outflux of K causes the membrane potential to return to normal
K channels begin to close
stage 5
membrane potential returns to normal
K channels close
stage 6
membrane shorts overshoots its resting value bbc of the accumulation of K outside of the cell
