Electrical Signaling

Question 1

____ ____ are the vocabulary of the nervous system

Answer 1

Electrical signals

Question 2

____ signals are how ____ is transmitted from cell to cell

Answer 2

Chemical; information

Question 3

Membrane potential

Answer 3

An electrical-potential difference across the membrane

Question 4

Characteristic resting membrane is in the range of ____mV to ____mV, making the typical to be ____mV

Answer 4

-50; -90; -70

Question 5

The inside of the cell is more ____ relative to the outside

Answer 5

Negative

Question 6

Forces influencing ion distribution between in and out of a cell

Answer 6

Diffusion force and electrostatic force

Question 7

Diffusion force is founded on a ____ gradient, in which molecules move from ____ to ____ of the concentration gradient to achieve ____

Answer 7

Chemical; High; Low; Equilibrium

Question 8

Electrostatic force is on a ____ gradient, in which ____ charges repel and ____ charges attract

Answer 8

Electrical; like; opposite

Question 9

Equilibrium potential

Answer 9

Potential at which opposing forces reach equilibrium

Question 10

Na+/K+ pump (Na+/K+ ATP-ase) moves ____ Na+ out for ____ K+ in

Answer 10

3; 2

Question 11

Concentration of ions & polymers outside of cell

Answer 11

• Na+: Many
• K+: Few
• Cl-: Many
• Ca2+: Many
• Proteins: Few

Question 12

Concentrations of ions & polymers inside of cell

Answer 12

• Na+: Few
• K+: Many
• Cl-: Few
• Ca2+: Few
• Proteins: Many

Question 13

Hyperpolarization of a neuron is due to an ____ of K+ ions and an ____ of Cl- ions, making the inside of cell more ____, resulting in a ____ in voltage

Answer 13

Efflux; Influx; Negative; Decrease

Question 14

Depolarization of a cell is due to an ____ of Na+ through ____ ____, making the inside of cell more ____, resulting in an ____ in voltage

Answer 14

Influx; Na+ Channels; Positive; Increase

Question 15

Types of sub threshold responses

Answer 15

IPSP (Inhibitory postsynaptic potential) & EPSP (Excitatory postsynaptic potential)

Question 16

IPSP (Inhibitory postsynaptic potential)

Answer 16

• Produces a small hyperpolarization, pushes the cell away from the threshold
• Typically result from Cl- ions entering the cell / K+ ions leaving the cell

Question 17

EPSP (Excitatory postsynaptic potential)

Answer 17

• Produces a small local depolarization, pushes the cell closer to the threshold
• Typically result from positive ions entering the cell (ex. Na+), making the inside more positive

Question 18

Action potential

Answer 18

Brief but large changes in membrane potential

Question 19

Action potentials are triggered when a ____ ____ ____ is reached, which involves the triggering of ____-gated channels

Answer 19

Threshold membrane potential; Voltage

Question 20

Membrane potential returns to its baseline when ____-gated ____ and ____ channels are ____ and the ____ ____ helps restore ion balance

Answer 20

Voltage; Na+; K+; Na+/K+ pump

Question 21

Axon hillock

Answer 21

A region in the axon densely packed with voltage-gated Na+ channels, also where action potentials originate from

Question 22

Absolute refractory period

Answer 22

• Voltage-gated Na+ channels open (inactivated)
• Voltage-gated K+ channels are closed

Question 23

Relative refractory period

Answer 23

• Voltage-gated Na+ channels are closing and re-activating
• Voltage-gated K+ channels are opened and slowly closing

Question 24

Action potential is ____ or ____: only when the threshold is reached can the action potential be fired

Answer 24

All; None

Question 25

Because of the refractory periods, there is ~____ msec limit on how frequently APs can occur * Firing rate max is ~____/sec

Answer 25

5; 200

Question 26

Refractory periods prevent the AP from ____ ____

Answer 26

Reversing direction

Question 27

Speed of transmission of AP depends on the size of the ____: The larger it is, the ____ it takes to transmit the information

Answer 27

Axon; Longer

Question 28

Saltatory conduction gives the axon the ability for…

Answer 28

- Faster conduction - Less metabolic “cost”

Question 29

The Na+/K+ pump locate between the ____ ____ on an axon, where it is named the ____ ____ ____

Answer 29

Myelin sheath; Node of Ranvier

Question 30

The Summation Mechanism of Axons

Answer 30

- If the overall sum of IPSPs and EPSPs can sufficiently depolarize the cell at the axon hillock, an action potential will occur

Question 31

Temporal summation

Answer 31

The summing of potentials that arrive at the axon hillock at different TIMES - The closer together they arrive, the greater the summation

Question 32

Spatial summation

Answer 32

Summing of potentials that come from different PARTS of the cell - The closer the synapses are to the axon hillock, the greater the summation

Question 33

Neuromuscular junction

Answer 33

a synaptic connection between the terminal end of a motor nerve and a muscle

Question 34

Types of neuron-neuron synapses

Answer 34

- Axo-dendric (axon to dendrite) - Axo-somatic (axon to soma) - Axo-axonic (axon to axon — mediates the effect of membrane potential from other neuron) - Dendro-dendritic (dendrite to dendrite)

Question 35

Gate 1 (voltage-gated Na+ channels)

Answer 35

Activation=voltage sensitive

Question 36

Gate 2 (Voltage-gated Na+ channels)

Answer 36

Inactivation=Voltage insensitive

Question 37

Subcategories of absolute refractory period

Answer 37

Depolarizing; Repolarizing

Question 38

The ____ of ____ ____ is perceived as pain

Answer 38

Inflammation; trigeminal nerves

Question 39

____ synapses are the vast MINORITY of synapses in the ____

Answer 39

Electrical; Brain

Question 40

Electrical synapses in synaptic communication has lined up ____ ____ that allows for ____ flow into the ____ neuron

Answer 40

Gap junction; Ion; Postsynaptic

Question 41

(Gap junction): Depolarization in ____ ____ leads to ____ ions moving towards post-synaptic cell

Answer 41

Presynaptic terminal; Na+

Question 42

Primary source of synaptic communication

Answer 42

Chemical synapses (neurotransmitters)