2.2 Electrical Signals in Neurons

Question 1

Two types of electrical signals (and their differences)

Answer 1

Graded potentials: short communication

Action potentials: long distance

Question 2

Action potential in muscles and neuron

Answer 2

muscle action potential

nerve action potential

Question 3

upper motor neuron

Answer 3

type of motor neuron

synapses with the lower motor neuron farther down the CNS

to contract a skeletal muscle

Question 4

membrane potential

Answer 4

electrical potential differerence (voltage) across the membrane

Question 5

electrochemical gradient

Answer 5

concentration (chemical) diff + electrical difference

note: ions move from high to low conc.

Question 6

Four types of ion channels

Answer 6

leak channels

ligand-gated channels

mechanically-gated channel

voltage-gated channel

Question 7

leak channel

Answer 7

randomly alternate between open and close positions

Note: more K+ leak channels than Na+, and K+ is leakier,
so membrane is more permeable to K+

Question 8

ligand-gated channel

Answer 8

open and close in response to ligand (chemical) stimulus

Question 9

mechanically-gated channel

Answer 9

open / close depending on mechanical stimulation in the form of vibration, touch, pressure, or tissue stretching

Question 10

voltage-gated channel

Answer 10

open / close depending on change in membrane potential (voltage)

Question 11

why does the resting membrane potential exist?

Answer 11

bc of small buildup of (—) ions in the cytosol and (+) ions in the ECF

Question 12

Resting membrane potential arises from these 3 factors

Answer 12

1) Unequal distribution of ions in the ECF and cytosol
—ECF is rich in Na+ and Cl-, Cytsol has K+ and phosphates attached to molecules

2) Inability of most anions to leave the cell

3) Electrogenic nature of the Na+-K+ATPases
—they expel 3 Na+ for each 2 K+ imported
—called electrogenic

Question 13

graded potential and the two types

Answer 13

small deviation from resting membrane potential
happens when stimuli causes mechanically-gated or ligand-gated channels to open or close

—Hyperpolarizing and depolarizing: makes the membrane more or less polarized

Question 14

decremental conduction

Answer 14

graded potentials tthat die out as they spread along the membrane

Question 15

summation

Answer 15

graded potentials that become strong or lost longer by summating with other graded potentials

Question 16

Postsynaptic potential

Answer 16

graded potential occurring in dendrites or cell body of a neuron in response to a neurotransmitter

Question 17

receptor potentials and generator potentials

Answer 17

potentials that occur in sensory receptors and sensory neurons

Question 18

action potential / impulse

two phases?

Answer 18

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

• depolarizing and repolarizing phase

Question 19

depolarizing phase

Answer 19

negative potential becomes less negative, reaches zero, and then becomes positive

Question 20

repolarizing phase

Answer 20

membrane potential is restored to the resting state of -70mV

Question 21

after-hyperpolarizing phase

Answer 21

membrane potential temporarily becomes more negative than the resting level

Question 22

all-or-none principle

Answer 22

action potential that either occurs completely or not at all