Nervous System 1

Question 1

Sensory neurons

Answer 1

Detect external and internal stimuli

Question 2

Interneurons

Answer 2

Receive and integrate sensory information (in the brain and ganglia)

Question 3

Motor neurons

Answer 3

Relay messages from interneurons and trigger effectors (muscles or glands)

Question 4

Membrane potential

Answer 4

Voltage across the plasma membrane (difference in electrical charge)
“Cell has membrane potential” - means one side of the cell is more positive than the other

Question 5

Resting potential (what side of the cell is +/- at this point?)

Answer 5

Membrane potential of a neuron not sending signals
Outside has a net + charge, inside has a net - charge (at resting potential)

Question 6

Action potential

Answer 6

Massive change in membrane voltage due to rapid changes in ion concentrations

Question 7

Sodium-potassium pumps (which ways do they move Na+ versus K+ to maintain resting potential?)

Answer 7

Maintain resting potential by moving Na+ and K+ against their concentration gradients
Na+ to the outside of the cell
K+ to the inside of the cell

Question 8

What do action potentials require? (most basic level)

Answer 8

The opening of ‘voltage-gated’ ion channels
Once a certain voltage is reached, the gated ion channels open, allowing ions to flow. Then it can change back to a closed state after the action potential completes and moves on

Question 9

Is Na+ (sodium) high inside or outside the cell during resting potential?

Answer 9

Outside!

Question 10

Is K+ (potassium) high inside or outside the cell during resting potential?

Answer 10

Inside!

Question 11

What is resting potential (in mV)?

Answer 11

-70 mV

Question 12

What is initial depolarization caused by?

Answer 12

Signals from other neurons.
Causes some opening of Na+ channels, to slowly increase the membrane potential.

Question 13

What is the threshold value? (mV)

Answer 13

-55 mV

Question 13

What is the action potential value? (mV)

Answer 13

30 mV

Question 13

What happens when the threshold value is reached? What does this do to the membrane potential?

Answer 13

Voltage-gated Na+ channels open, allowing Na+ to rush into the cell! This causes the membrane potential to drastically increase in the rising phase.
Threshold for Na+ channels = -55mV

Question 14

What happens once the action potential value is reached? What does this do to the membrane potential?

Answer 14

Voltage gated K+ channels open, allowing K+ to rush out of the cell. This drastically decreases the membrane potential, called the falling phase.
Voltage gated Na+ channels close.
Threshold for K+ channels = 30mV

Question 15

What happens at the end of the falling phase?

Answer 15

The membrane potential initially undershoots, and then the resting potential is reestablished (-70 mV).

Question 16

Refractory period (what happens?)

Answer 16

Temporary inactivation of Na+ channels after an action potential.
When Na+ rushes into the cell, that triggers the next Na+ channels to open, this signal propagates unidirectionally down the neuron.

Question 17

What is the inactivation loop? (a protien)

Answer 17

The inactivation loop protein plugs the Na+ channel for a few milliseconds after Na+ has rushed in and the signal has started to propagate down the axon. This allows for unidirectional propagation of the action potential.

Question 18

The speed of an action potential increases with the axon’s __________.

Answer 18

diameter! The bigger the better

Question 19

In vertebrates, __________ greatly increase speed of action potentials.

Answer 19

myelin sheaths!
They are made up of proteins and lipids, make up Schwann cells, and they serve as electrical insulation.

Question 19

Which statement best describes an action potential?
A) sodium-potassium pumps quickly pumping ions across the membrane
B) increases in ion channel expression in neuron dendrites, allowing sodium and potassium to move across the cell body membrane
C) the intracellular movement of neurotransmitters down the axon in one direction
D) opening and closing voltage-gated ion channels allowing certain ions to quickly diffuse across the plasma membrane of the axon

Answer 19

D

Question 20

What are the nodes of ranvier?

Answer 20

They are the gaps between Schwann cells of axon, that make the action potential jump. This greatly speeds up the process!

Question 21

Choose the set that includes the charged compounds that are more abundant inside neurons than outside neurons.
A) sodium and potassium ions
B) chloride ions and sodium ions
C) proteins and sodium ions
D) potassium ions and protein

Answer 21

D

Question 22

___ signaling releases neurotransmitters.

Answer 22

Calcium

Question 23

Explain the process (generally) of how calcium signaling works to release neurotransmitters.

Answer 23

At the end of the pre-synaptic cell, there are voltage gated Ca2+ channels. Once the signal hits, these channels are opened, and calcium rushes into the pre-synaptic cell

Question 24

What do neurotransmitters bind to? What causes the signal in the next cell to start?

Answer 24

They bind to receptors on the post-synaptic membrane, onto ligand-gated ion channels. Once they bind, those channels open, letting K+ out of the postsynaptic cell, and Na+ into it. This is the cause of the initial signaling.

Question 25

What are excitatory postsynaptic potentials (EPSP’s)?

Answer 25

Depolarizations that bring the membrane potential toward threshold

Question 26

What are Inhibitory postsynaptic potentials (IPSP’s)?

Answer 26

Hyperpolarizations that move the membrane potential father from threshold.

Question 27

EPSP’s and IPSP’s are ‘summed’ to generate/not generate ___________.

Answer 27

An action potential.
The different signals from different neurons will add up to whether or not the postsynaptic neuron reaches the threshold of an action potential. Depends on whether or not it is depolarized enough to generate an action potential.

Question 28

What are 4 things neurotransmitters do? Give examples of each type.

Answer 28

1. Can be excitatory (glutamate) or inhibitory (GABA)
2. Can trigger ‘feelings’ (ex. depression, pain)
3. Can be mimicked (ex. by Nicotine, LSD, or Opiates)
4. Can be manipulated (ex. by Botox, Valium, or Prozac)

Question 29

What do inactivating enzymes do?

Answer 29

They can break down neurotransmitters in the synaptic cleft (inactivate them).

Question 30

What does a neurotransmitter transpory channel do?

Answer 30

It aids in the reuptake of neurotransmitters into the presynaptic cell.

Question 31

Of these choices, neuronal communication between the brain and the muscles of the leg is best conceptualized as…
A) Electrical signaling
B) Chemical signaling
C) Genetic activation
D) Electrical and chemical signaling

Answer 31

D