Chapter 4: Neurophysiology

Question 1

Resting Neuron

Answer 1

Is Polarized

Different charge between inside and outside of cell

Resting cell is more negative on inside

Question 2

Ion Movement

Answer 2

Diffusion: ions spread towards uniform concentration

electrostatic pressure: causes ions to glow towards oppositely charted areas

Question 3

Ionic basis of resting membrane potential

Answer 3

1) Potassium ions (K+) accumulate inside cell and diffuse through membrane
2) Negative charge builds in cell, electrostatic pressure pulls K+ back in

For every 3 Na+ pumped out 2 K+ ions are pumped in

Question 4

Action Potential

Answer 4

Brief but large change in membrane potential originating at axon hillock

Hyperpolarization: inside of cell becomes even more negative

Depolarization: decrease membrane potential interior becomes less negative

Question 5

Graded Response

Answer 5

Magnitude of response is correlated to magnitude of stimulus

Question 6

Local Potential

Answer 6

As potential spreads across membrane it diminishes

Question 7

Action Potentials

Answer 7

Produces by sudden rush on Na+ into cell until equilibrium is reached

As inside of cell become positive voltage gated K+ channels open and potassium rushes out until resting potential is reached

Question 8

Voltage gated sodium ion channels

Answer 8

Change shape and open in response to threshold depolarization

More voltage gates open means more Na+ rushes into cell

Happens until Na+ equilibrium is reached at around +40 mv

Question 9

Refractory Phase

Answer 9

Membrane becomes temporarily unresponsive to subsequent stimuli after action potential is reached

Two phases:

1) Absolute
2) Relative

Question 10

Saltatory Conduction

Answer 10

Potential traveling inside axon jumps from node to node

Question 11

Postsynaptic Potentials

Answer 11

Brief changes in membrane potential of postsynaptic cell in response to neuro transmitter

Question 12

Excitatory postsynaptic potentials

Answer 12

Small, local depolarization that pushes postsynaptic cell closer to action potential

Increases likelihood of neuron firing

Na+ channels

Question 13

Inhibitory postsynaptic potentials

Answer 13

Hyper-polarizing postsynaptic potentials that pushes cell away from threshold

Decreases likelihood of neuron firing action potential

Cl- ions rush into cell

Question 14

Spatial Summation

Answer 14

Summing of all potentials that reach axon hillock from locations across cell body

Question 15

Temporal Summation

Answer 15

Summing of all potentials based on time of arrivals

Question 16

Types of synapses

Answer 16

4 kinds:

1) Axo-dendritic
2) Axo-somatic
3) Axo-axonic
4) Dendro-dendritic

Question 17

Important ions

Answer 17

Sodium Na+
Potassium K+
Calcium Ca2+
Chloride Cl-