Nerve Impulse Transmission

Question 1

Nerve action potentials

Answer 1

nerve impulses consist of a flipping of charges along the length of the neuron

Question 2

When not conducting impulses, neurons are considered to be:

Answer 2

at rest

Question 3

Resting membrane potential

Answer 3

a measure of the charge difference between the inside and outside of the neuron

it is measured inside the cell and averages 70mV (millivolts)

*don’t need to know number

Question 4

at rest the outside of the neuron is _____ charged and the inside of the neuron is more _____ charged

Answer 4

outside more positively charged

inside more negatively charged

Question 5

Often, movement through the neuron membrane occurs through _____ _____ embedded in the ______ ______

Answer 5

through PROTEIN CHANNELS embedded in the PLAMSA MEMBRANE

Question 6

What can pass through the protein channels in the plasma membrane?

Answer 6

ions

**not in bold but may be good to know below **

Positive ions move towards negatively charged areas while negative ions move towards positively charged areas

Question 7

Ions move across plasma membranes through ____ ____ when ____ ____

Answer 7

through ION CHANNELS when GATES OPEN

Question 8

Resting membrane potential develops due to a small buildup of NEGATIVE IONS in the ______________ and a slight build up of POSITIVE IONS in the ________

Answer 8

a small buildup of NEGATIVE IONS in the CYTOSOL OF THE CELL JUST INSIDE THE PLASMA MEMBRANE and a slight build up of POSITIVE IONS in the EXTRACELLULAR FLUID JUST OUTSIDE THE PLASMA MEMBRANE

Question 9

As the inside and outside of the cell have different net charges, cells may be referred to as _____ when this resting membrane potential exists

Answer 9

polarized

Question 10

sodium-potassium pumps

Answer 10

actively move Na+ outside of the cell and K+ into the cell

for every 3 Na+ ions moved out only two K+ ions are moved in, this imbalance in positive ions inside and outside of the cell helps maintain resting membrane potential

Question 11

Action potentials

Answer 11

occur when the resting membrane potential is reversed

result form a movement of ions in and out of cell through the plasma membrane

Question 12

Depolarization

Answer 12

as the poles inside and outside of the cell are changing, the flipping of charges is referred to as depolarization

Question 13

repolarization

Answer 13

the return to resting membrane potential

for a neuron to be able to convey numerous impulses, it needs to return to its resting state after depolarizing

Question 14

refractory period

Answer 14

the time it takes to repolarize

the time it takes for another action potential to generate after an action potential has already been generated

Question 15

action potentials occur on a _______ basis

Answer 15

all or nothing

Question 16

two key factors that affect the velocity of nerve impulses

Answer 16

myelination and axon diameter

Question 17

Myelinated axons

Answer 17

only the portions of the axon that need to depolarize are small sections of axon not covered with myelin known as the nodes of Ranvier

the impulse jumps from gap to gap, taking less time as less axon needs to depolarize

Question 18

large diameter axons present a larger surface area to propagate action potentials and are…

Answer 18

faster than axons of a narrower diameter

Question 19

Synapses

Answer 19

the spaces between neurons and other neurons, or between neurons and their large organ

Question 20

neurotransmitters are needed because

Answer 20

actions potentials cannot jump across these gaps, so neurons convey impulses across synapses by way of neurotransmitter

Question 21

Neurotransmitters may have a ____ or ___ effect

Answer 21

excitatory or inhibitory

Question 22

numerous chemicals may act as ____

Answer 22

neurotransmitters

Question 23

converging circuits

Answer 23

several pre-synaptic neurons communicate with one post-synaptic neuron

Question 24

diverging circuits

Answer 24

one pre-synaptic neuron meets with several post-synaptic neurons