Nervous System Unit Lesson 2: Nerve Impulses Flashcards
what is voltage
potential difference or “electric pressure”
how do nerves transmit signals
they do this through nerves impulses
how does an oscilloscope work
it measures the potential difference between two points along a neuron and graphs them as they occur
what is the resting potential
the difference in charge between the inside of the cell and the outside of the cell when a neuron is not performing an impulse
what is the resting potential measured at and what does that mean
-70mV, and it means that the interior of the cell is more negative than the exterior
describe the concentration of sodium ions (Na+) outside of the neuron
it is high
describe the concentration of potassium ions(K+) outside of the neuron
it is low
describe the concentration of sodium ions(Na+) inside the neuron
it is low
describe the concentration of potassium ions(K+) inside the neuron
it is high
what happens to the polarity when a nerve impulse fires and why
there will be a rapid changing of polarity because of the separation of charges
how is the separation of charge inside and outside the neural membrane accomplished
it is accomplished through channel proteins and sodium-potassium pumps which are closed until there is an impulse
what are the sodium-potassium pumps responsible for
they are responsible for pumping sodium and potassium across the membrane, against the concentration gradient
when a nerve impulse fires, why is there a rapid changing of polarity
it is because of the movement of ions across the membrane
what is action potential
the movement of ions across the membrane/ the change in polarity
what are the 4 steps to action potential
- sodium gates open 2. potassium gates open 3. conduction of action potential 3. synaptic transmission
explain the beginning of an action potential(details)
when the sodium gates open, the numerous sodium ions move across the membrane due to the concentration gradient, and this movement causes the potential to rapidly change from -70mV to 35mV
what is depolarization
when the total charge of anions in the membrane are now outnumbered by cations due to the potassium ions already in the neuron and the added sodium ions after the first step of action potential
what is inside a neuron
a very large concentration of anions and a large concentration of potassium ions
explain the second step of an action potential(potassium gates)
the potassium gates open that allows the movement of potassium ions across the membrane to outside the neuron. the low concentration of potassium ions outside the neuron causes movement across the membrane through potassium channels.
what is repolarization
it is when the total negative charge inside the membrane is now greater than the positive charge, re-establishing the concentration gradient of charge where outside the neuron is more positive than inside. this happens during the second step of action potential
what is the only way action potential be achieved (request potential)
if the request potential is present to begin the depolarization process. the potential must rise from the resting -70mV to roughly -55mV to -50mV
what is a refractory period
it is a short period of time where another action potential can occur at the same area
describe the refractory period
it is when the sodium-potassium pumps work to re-establish ion concentrations inside and outside the cell membrane
what is saltatory conduction
it is when the action potential is said to “jump” between regions on the axon(because of the myelin sheath that covers regions of the axon)
what is an axon terminal and where is it located
it is a small bulb-like terminus which is located at the end of each axon. it is extremely close to the neighbouring dendrite.
what is a synapse
the region of the axon terminal and the neighbouring dendrite
what is a synaptic cleft
the gap between the axon terminal and the neighbouring dendrite
what is the presynaptic neuron
the neuron before the synaptic cleft
how is the signal that an action potential represents carried across the synapse
using neurotransmitters
explain the process of transporting the signal across the synapse
when the action potential reaches the synapse, gated calcium channels open and calcium ions(Ca2+) enter the axon terminal. these ions cause contractile proteins to pull vesicles containing neurotransmitters to the synapse, where they fuse with the membrane and leave via exocytosis
