Lecture 2

Question 1

Resting potential has an electrical gradient of? And what doesn’t it mean?

Answer 1

Of -70 or -80 mv the important thing is to realize that the neuron is negatively charged during rest compared to the outside

Question 2

Important chemistry playing?

Answer 2

Na+ (sodium) K+ potassium Cl- (chloride) and A- (anions just variously negative charged ions)

Question 3

The ion channels can be?

Answer 3

Gated always

Non gated

Question 4

What is selective permeability

Answer 4

Neurons are selectively permeable because of ions

Each ion channel works only for one type of ion

Question 5

What is active and passive motion?

Answer 5

Passive when the ion channel is opened and the ion just passes through

Active we’ll see later

Question 6

Concentration gradient?

Answer 6

Concentration of a particular ion on the inside compared to the outside

Like not too much sodium during rest within but a lot outside

Diffusion happens when there’s a lot of unbalance

Question 7

Why is the electrical gradient important?

Answer 7

If there’s a lot of positive ions within the neuron then the positive ions will want to move outwards

So it doesn’t only work for the concentration gradient

• and + like each other

Question 8

During rest potential Na+?k+ etc

Answer 8

Lot of sodium outside little inside

Lot of potassium inside little outside

Lot of chloride outside that’s inside

Lot of anions inside little outside

Question 9

Non gated channel?

Answer 9

Always opened channel

Question 10

Which one can move more or less freely in rest?

Answer 10

K+

Question 11

What is a sodium potassium pump?

Answer 11

A pump continuously working each time it works it pumps 3 sodium outside and 2 potassium inside

Trying to make sure that the resting potential stays in place

Question 12

Why is potassium free in rest?

Answer 12

Because potassium channels are open and pump is continuously working

Question 13

What is the equilibrium potential?

Answer 13

Ewhen concentration gradient and electrical gradient balance each other (putting potassium in and out till they’re chargeky balanced

Question 14

How do you measure the restaurant by potential?

Answer 14

You put a wire in the neuron and see the electrical charge

Using an amplifier

Question 15

What do you need for the generation of an action potential,

Answer 15

You need a stimulus

Question 16

What happens if the stimulus is not Hug enough?

Answer 16

Fieles potential

Question 17

When do you get an action potential

Answer 17

When you pass the threshold

Question 18

Depolarization?

Answer 18

Graphs goes up the threshold

Question 19

Repolarization ?

Answer 19

Going down back the threshold

Question 20

refractory period or hypopotential?

Answer 20

Going even more down

Question 21

What is the hodgkin Huxley cycle

Answer 21

Synaptic potential receptor potential (stimulus)

Then depolarization

Then sodium channels are opened(used to be closed at rest)

Then Na+ flows into the neuron (because it is negatively charged within and because there’s a higher concentration of Na+ outside the neuron electrical and concentration gradient

The cycle keeps happening till you reach the threshold and action potential happens

Question 22

Action potential So you start with Na+ flowing into neuron then what?

Answer 22

Na+ so many within so neuron wants to release some positivity opening even more channels of potassium due to concentration gradient

Action potential pushes potassium out

This process is called repolarization/undershoot

Question 23

If repolarization ir undershoot reaches a higher negativity than the one the neuronbhad before the action potential what do we have?

Answer 23

A refractory period

Question 24

What happens during a refractory period

Answer 24

It is either impossible to generate a new action potential or quite hard

All sodium channels are closed so no positive charge can come in

Question 25

What is a relative refractory?

Answer 25

When it is more difficult to get an action potential

Question 26

Where does the dirt action potential happens?

Answer 26

Axon hillock(integration zone a lot of charges coming in)

Question 27

What do we want the actiovpotential to do?

Answer 27

To travel the axon to the end to terminal buttons

Question 28

Travel of AP from axon hillock through axon to terminal buttons?

Answer 28

Propagation

Question 29

What is mode of ranvier?

Answer 29

Parts of axon not covered by myelin sheath

Question 30

Action potential happens continuously in?

Answer 30

Nodes of ranvier lots of sodium depolarizing through the axon (propagation potential)

Question 31

Passive diffusion happens in?

Answer 31

Myelinated portions

Question 32

So how does action potential happen?

Answer 32

Action potential refractory behind then behind the one before become action potential and like that so always to the right cause refractory area won’t fire and resting area is separated by the refractory from the action potential

Question 33

What are excitatory postsynaptic potential and inhibitory postsynaptic potential

Answer 33

Excitatory -brings positive charge/depolarization

Inhibitory - negative charge/hyperpolarization

They’re grade meaning some are stronger than other la

Fast

Decremental(diffusion happening u know)

Temporal/spatial summation