Exam 2: Action Potentials Continued

Question 1

When the cell is hyperpolarized, does it take more or less stimulus to turn the cell back on?

Answer 1

More

Question 2

T/F If sodium channels don’t reset, they can still be used

Answer 2

False; they need to be reset to be used again

Question 3

During depolarization, what are the two important factors seen in the Goldman equation?

Answer 3

1. Concentration gradients for ions
2. Permeability for ions

Question 4

T/F Chloride is found in the nervous system and hyperpolarizes/suppresses electroactivity

Answer 4

True

Question 5

What occurs in GABA receptors?

Answer 5

GABA receptors open up chloride channels in neurons which allows chloride to flood in and make the cell more negative

Question 6

How many binding sites does acetylcholine have?

Answer 6

2

Question 7

What connects the neurotransmitter to a neurotransmitter receptor?

Answer 7

Neuromuscular junction

Question 8

Where are nicotinic acetyl choline receptors found?

Answer 8

Skeletal muscles and brain

Question 9

Do both binding sites for Ach have to be occupied to allow current to run through it?

Answer 9

Yes

Question 10

What is a nicotinic acetyl-choline receptor? (nACh)

Answer 10

Donut shape protein in the cell wall that is lined w/ amino acids that have a negative electrical charge; the negative charge repels negatively charged electrolytes from moving through the channel

Question 11

Which electrolyte easily gets through nACh receptors?

Answer 11

Sodium; majority of the current that goes through is sodium b/c it is the easiest to get through since it moves down its concentration gradient

Question 12

How is potassium prevented from leaking out of the cell?

Answer 12

Sodium wants to flow in so badly that it prevents the potassium from leaking

Question 13

Which other ion can move into the cell to also depolarize it?

Answer 13

Calcium

Question 14

Why doesn’t calcium just flow into the cell?

Answer 14

Because it is large and “clunky” per Schmidt

Question 15

Describe how a neuron talks to skeletal mm.

Answer 15

A motor neuron is connected to skeletal muscles via the NMJ (neuromuscular junction), where ACh (neurotransmitter) is released to bind to 2 sites on the receptor. Once ACh binds, this causes an action potential to spread along the muscle fiber on both sides and signals to the muscle to contract and move.

Question 16

Where do paralytics work?

Answer 16

NMJ (Neuromuscular junction)

Question 17

What is another example of how to turn on neurons?

Answer 17

Via physical pressure

Question 18

Where can physical pressure turn on neurons?

Answer 18

Anywhere in the body where we sense pressure

Question 19

How does pressure turn on neurons?

Answer 19

We have a specialized structure with an oval sensor that notices a change in pressure and causes the stimulus to be turned into an action potential, travels up the neuron, and sends the information back to the nervous system for processing.

Question 20

Does pressure increase or decrease sodium permeability?

Answer 20

When pressure increases, the sensor (containing sodium channels) flattens, causing the wells of the sodium channels to become wider and allowing more sodium to come into the cell which leads to an action potential.

Question 21

Can action potentials spread both ways or only one direction?

Answer 21

Action potentials can spread both in one direction as well in both directions

Question 22

If an action potential spreads in both directions, does this excite cells much faster or slower?

Answer 22

Faster; spreading in one direction would excite cells slower

Question 23

T/F Action potentials are examples of positive feedback

Answer 23

True; there is an initial stimulus, sodium comes into the cell which leads to more and more sodium coming in until it reaches the entire length of the action potential

Question 24

What determines action potentials?

Answer 24

Threshold potentials

Question 25

Threshold potentials are _____ from cell to cell.

Answer 25

Different

Question 26

If a threshold is -70 and something passes the threshold, what occurs?

Answer 26

An action potential will be fired

Question 27

What occurs when we experience a weak stimulus that barely passes the threshold?

Answer 27

The firing might cause a delay in an action potential being fired

Question 28

T/F Action potentials are NOT specialized to whatever role the cell is doing

Answer 28

False

Question 29

Why is the action potential of the heart sustained longer than that of a neuron?

Answer 29

The heart needs time to contract and push blood through the heart so action potential are longer

Question 30

What type of channels open slowly after depolarization of an action potential of the heart?

Answer 30

Voltage gated calcium channels

Question 31

Which ion is entered into the cell during depolarization of a heart action potential?

Answer 31

Calcium

Question 32

T/F The length of the nerve does not affect the time it takes to send an electrical signal

Answer 32

False; when you have a long nerve, it takes longer for the electric signal to be sent compared to a short nerve

Question 33

When a nerve is wider does is it faster or slower? Does it have more or less resistance?

Answer 33

Wider = FAster and less resistance