Neurophysiology Continued

Question 1

a hyperpolarizing potential in the postsynaptic membrane
that pushes the cell further away from the threshold, decreasing likelihood of the neuron firing an action potential

• result when chloride ions (Cl-) rush into the cell, making the inside more negative

Answer 1

Inhibitory Postsynaptic Potential (IPSP)

Question 2

a small local depolarizing potential in the postsynaptic membrane that pushes the cell closer to the action potential threshold, increasing the likelihood that the neuron will fire an action potential

• Na+ channels open, letting positive ions into the cell (and making the inside of
  the cell more positive

Answer 2

Excitatory Postsynaptic Potentials (EPSP)

Question 3

The brief changes in the membrane potential of the postsynaptic cell are called

Answer 3

postsynaptic potentials

Question 4

• the potential traveling inside the axon jumps from node to node
  When the action potential reaches the end of an axon, it causes the axon to release a chemical called a neurotransmitter
• The neurotransmitters bind to receptors on the postsynaptic membrane and briefly alter the
  membrane potential of that cell by allowing different ions to enter

Answer 4

Saltatory Conduction

Question 5

Action potentials start at the axon hillock, and are actively propagated (regenerated) along the axon at the…

• Analogy: like fire spreading down a matchbook

Answer 5

nodes of Ranvier, where voltage-gated ion channels are located

Question 6

only very strong stimulation can produce an action potential

Answer 6

relative refractory phase

Question 7

no action potentials can be produced

Answer 7

absolute refractory phase

Question 8

the neuron either fires or does not, and the amplitude of the action potential is independent of stimulus size (so, they are not local or graded)

Answer 8

all-or-none property

Question 9

also produces local, graded responses BUT, if the stimulus depolarizes the membrane to the threshold of activation (-40 mV) it triggers an action potential

• The membrane potential changes rapidly, and the inside of the cell becomes positive (briefly!) and then comes back down

Answer 9

depolarizing stimulus

Question 10

as the potential spreads across the membrane, it diminishes (or becomes weaker) as it moves away from the point of stimulation

Answer 10

Local Potential

Question 11

this means that the greater the stimulus, the greater the response; thus, the change in potential

Answer 11

graded response

Question 12

produces a response that passively mirrors the stimulus

Answer 12

hyperpolarizing stimulus

Question 13

making the membrane potential of a neuron less negative on the inside

• So, bringing it closer to zero, like up to -60mV

Answer 13

Depolarization

Question 14

• making the membrane potential of a neuron more negative on the inside
• So, if the resting membrane potential of the neuron is usually -65mV, this takes it further away from zero (e.g., to -70mV)

Answer 14

Hyperpolarization

Question 15

• are brief, but large changes in membrane potential
• They originate at the axon hillock and propagate along the entire axon; this is how neurons communicate with one another

Answer 15

Action Potentials

Question 16

• Pumps three sodium ions (Na+) out for every two K+ ions pumped in
• K+ ions diffuse out through their selectively-permeable ion channels, and the pump brings them back in

Answer 16

pump process

Question 17

Neurons use energy to operate __ to help maintain the membrane potential

Answer 17

sodium-potassium pumps

Question 18

causes ions to flow towards oppositely charged areas

Answer 18

Electrostatic Pressure