LESSON 4

Question 1

• for short distance communication

Answer 1

graded potentials

Question 2

• for long distance communication

Answer 2

action potentials

Question 3

4 types of ion channels

Answer 3

leakage channels
voltage-gated channels
ligand-gated channels
mechanically-gated channels

Question 4

• protein channels present in the plasma membrane of neurons and muscle fibers which open and close to allow certain ions to move across the plasma membrane

Answer 4

ion channels

Question 5

• Their gates randomly alternate between open and closed spots

Answer 5

leakage channel

Question 6

• They open in reaction to a change in membrane potential (voltage)

Answer 6

voltage-gated channel

Question 7

• These channels open and close in response to a specific chemical stimulus/binding of a ligand or chemical stimulus

Answer 7

ligand-gated channel

Question 8

• Open and close in reaction to mechanical stimulation specifically vibration (sound waves), pressure (touch) or tissue stretching
• The force alters the channels from their resting position, thus opening the gates

Answer 8

mechanically-gated channel

Question 9

• voltage difference between the inside and
  outside of a cell membrane when the cell is not responding to a stimulus

Answer 9

resting membrane potential

Question 10

in many neurons and muscle fibers, it is __ to __ mV

Answer 10

-70 to -90 mV

Question 11

• series of rapidly occurring events that
  decrease and reverse the membrane potential and then eventually restore it to the resting state

Answer 11

action potential/nerve impulse

Question 12

2 main phases of action potential:

Answer 12

• depolarizing phase
• repolarizing phase

Question 13

• the voltage-gated channels open and
  an action potential of the same amplitude occurs when depolarization reaches a threshold point

Answer 13

all-or-none principle

Question 14

threshold point in many neurons

Answer 14

-55 mV

Question 15

• a weak depolarization that cannot bring the membrane potential to threshold

Answer 15

subthreshold

Question 16

• a stimulus that is just strong enough to depolarize the membrane to threshold

Answer 16

threshold

Question 17

• a stimulus that is strong enough to depolarize the
  membrane above threshold

Answer 17

suprathreshold

Question 18

a reduction of voltage across a plasma membrane
(the interior surface of the plasma membrane becomes less negative/more positive than the outside) as a result of the opening of the voltage-gated sodium channels, allowing the inward flow of sodium ions

Answer 18

depolarization

Question 19

• restoration of a resting membrane potential after
  depolarization

Answer 19

repolarization

Question 20

• Action potentials are self-propagated, and once started the action potential progresses along the axon membrane

Answer 20

propagation/conduction of nerve impulses

Question 21

the membrane is ____ behind the leading edge of a nerve impulse

Answer 21

• refractory

Question 22

• happens in unmyelinated axons
• Ions flow through their voltage-gated
  channels in each adjacent segment of
  the membrane

Answer 22

continuous conduction

Question 23

• happens along myelinated axons
• Ions flow through their voltage-gated
  channels from one node to the next
  node of Ranvier

Answer 23

saltatory conduction

Question 24

• Impulse traverse the entire length of
  an axon
• Nerve impulse propagates only at a
  relatively SHORT distance

Answer 24

continuous conduction

Question 25

- Impulse leaps/jumps from one node to the next - Nerve impulse propagates MORE RAPIDLY / towards a FARTHER distance

Answer 25

saltatory conduction

Question 26

- slower, uses more energy, less efficient - uses higher number of ion channel

Answer 26

continuous conduction

Question 27

- faster, uses minimum voltage channel - prevent delay of nerve impulse - more efficient - uses less energy

Answer 27

saltatory conduction

Question 28

what do you call the interval of complete unresponsiveness

Answer 28

absolute refractory period

Question 29

- a second action potential cannot be initiated, even with a very strong stimulus

Answer 29

absolute refractory period

Question 30

- period where stronger than minimum effective stimulus will lead to the transmission of a nerve impulse called

Answer 30

relative refractory period

Question 31

The change allows the influx of Na+ ions into the cell leading to

Answer 31

depolarization

Question 32

Resting state is restored by the outflow of K+ ions out of the cell leading to what you call

Answer 32

repolarization

Question 33

At a _______, a presynaptic neuron converts an ______ into a ________. The postsynaptic neuron then converts the chemical signal back into an ______

Answer 33

chemical synapse electrical signal (nerve impulse) chemical signal (neurotransmitter release) electrical signal (postsynaptic potential)

Question 34

- Nerve impulse propagation in which the impulse “leaps” from one node of Ranvier to the next along a myelinated axon is

Answer 34

saltatory conduction

Question 35

Axons with larger diameters conduct impulses at ______

Answer 35

higher speeds