Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

U0 Biology 115 > 3 lecture 5 > Flashcards

3 lecture 5 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

How does the brain work?

A

stimulus –> processing –> behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is Stimulus

A

this is any input

light, sound, touch, taste, gravity, movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is Processing

A

what you do with the information
This can be very simple (like a reflex when you touch a hot pan or your need to breathe harder when running) It can be complex
(taking an exam or determining when and whether to swing at a baseball pitch)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is Behavior

A

this is anything you do in response Removing your hand from the pan, filling in the circle for answer ‘A’, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the definition of action potential

A

an electrochemical wave, driven by the movement of ions along their electrical and concentraFon gradients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are neurons

A

cells

they contain the same complement of organelles, cytoskeleton, DNA, etc. as other cells
SSthey also have features that make them distinct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are dendrites

A

Processes near the cell body Receive input from other neurons

(branches out from neutron body)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is an axon

A

Main conducting unit of the neuron

Can convey information great distances by propagating an electrical signal (the action poten’al)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the synapse

A

Used to communicate that signal to other neurons

Where the terminal of one cell connects to the dendrites of another cell is the synapse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is concentration gradient

A

Molecules move from areas of high concentration to low concentration
until they are evenly distributed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

can diffusion still happen even when there is a barrier with a hole in it

A

yes, it will just happen more slowly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is there a high concentration of outside of a neuron cell

A

High concentration sodium ions (Na+) OUTSIDE of the cell
Low concentration sodium ions INSIDE

This means we have a concentration gradient for sodium Na+ to go IN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

sodium has a positive charge, what does this mean for the neuron

A

the charge of the neuron will change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

charge particles can either be ____ or ____

A

positive or negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does it mean for a particle to be charged

A

they experience a force when they are around other charged parFcles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is voltage

A

it is a force that moves oppositely charged particles toward each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how do you create voltage

A

to create voltage, you need to separate two (or more) opposite charges

When you do this, when you separate charge, you create a voltage difference or potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is voltage difference

A

potential

That difference is a force, so that if you release the charges they will move toward one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does lightning relate to voltage

A

If you separate charge, you create a voltage difference or poten9al
Clouds moving over the surface of the earth produce a difference in charge, a potenFal, between the clouds and the surface
When that potenFal is released, i.e. the posiFve and negaFve charges connect, it’s lightning

current: the electricity or flow of charge that happens when there is a voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how can you relate gravity to voltage

A

If I separate a ball from the ground, I’ve created potential energy
When I release the ball, it should fall to the ground, pulled by a force (gravity)

This is how a battery works, the positive and negative charges are separated (creating a voltage)
Current:
If you connect a wire to them, completing the circuit, the electricity or current will move through the wire

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does electrical gradient work

A

If you separate the charge, for example with a membrane, you’ve created a voltage difference or potetial

If we add a channel to the membrane, our charged parFcles will flow through, down the electrical gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are the 2 types of gradients

A

concentration gradient

electrical gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is Concentration Gradient

A

Molecules move from areas of high

concentraFon to low concentration

24
Q

what is Electrical Gradient

A

Opposite charges move toward each other

25
Q

what are the 2 necessary parts to action potential

A

concentration and electrical gradient

26
Q

what is prominent inside the neuron cell before sodium moves in

A

inside the cell there are a lot of negatively charged proteins and some negative ions

27
Q

what is the change inside the cell

A

-70 mV

28
Q

how do e know it is -70 inside the cell

A

We measure it with ELECTRODES
thin pieces of metal that we place inside or outside the cell
let us monitor the potential

29
Q

describe how the sodium uses the electrical gradient to move inside the cell

A

High concentraFon of sodium ions Na+ OUTSIDE of the cell (therefore a LOW concentraFon INSIDE)
So, concentra’on gradient for sodium Na+ is to go IN

Meanwhile, inside the cell there are a lot of negaFvely charged Na+ proteins and some negative ions Na+

This gives us a voltage or poten9al of <70mV or so
Sodium, Na+, is a posiFvely charged ion

Thus, there is also an electrical gradient for Na+ to go IN

30
Q

what are channels a key part of

A

how neurons work

31
Q

how do channels open up

A

they open in response to

different changes in the cell

32
Q

what are ion channels

A

There are some channels just for Na+ (nothing else can flow through them)
They only let Na+ go one way: IN
Whether a channel is open or closed can depend on voltage
Na+ channels are normally closed at very low voltage
-70mV INSIDE = CLOSED

33
Q

if then inside id slightly LESS negative, what happens to the channels

A

they will open
(an be anything less than -70)

Once the channels open, Na+ will rush in

Pushed by both the Concentration gradient and The voltage difference or electrical gradient
The charge on the inside goes up eventually reaching +40 mV

34
Q

once the voltage gets really high (e.g 40mV), what happens

A

Then, once the voltage gets really high (e.g. +40 mV) the Na+ channels close

This is known as the refractory period
The channels go offline for a little while because they
need to reset
During that time, you can’t Na+ get them to open

35
Q

what happens in the refractory period

A

the cell closes the channels

36
Q

what is the resting potential

A

where the cell starts (the voltage it starts at)

37
Q

while there is sodium on the outside of the cell, what is on the inside

A

potassium

38
Q

what is the gradient for potassium

A

to go OUT

39
Q

how do we get from the refractory period to the start again

A

If the inside gets a liUle posiFve, it opens the Na+ channels, Na+ rushes in
This makes the inside of the cell gets less negaFve (now 0 mV for example)
This opens up K+ channels
K+ flows OUT
Na+ keeps flowing in until 40 mV inside
Sodium channels close
But K+ channels are still open
Concentration gradient and electric driving force still pushing K+ out
K+ continues to flow out until the voltage is below the
resting potential
(we’re not going to go into why it goes BELOW the resting potential, it just does)
K+ channels then close

That brings us back to -70 mV
But we’re not quite back to normal
Because now, All the K+ is now outside and all the Na+ is inside
the concentrations are reversed!
Fortunately, there is a pump It uses energy (ATP) to move K+ in and Na+ out until everything is back to normal

40
Q

why does K+ flow out

A

Concentration gradient

Less voltage holding K+ in

41
Q

what are the steps to action potential

A

Na+ channels open, Na+ begins to enter cell

K+ channels open, K+ begins to leave cell

Na+ channels become refractory, no more Na+ enters cell

K+ continues to leave cell, causes membrane potential to return to resting level

Extra K+ outside diffuses away

42
Q

how does action potential happen all the way down the axon

A

like dominos

At the start, the membrane is completely polarized
SSmore negaFve inside
Small increases in posiFve charge result in the opening of voltageSgated sodium channels and an influx of Na+
This Na+ influx further depolarizes the membrane (makes the inside more posiFve) The positive charge spreads passively, opens adjacent Na+ channels This repeats for the length of the axon
Meanwhile, voltage gated potassium (K+) channels open, and Na+ channels close K+ flows out and the inside become negaFve again

43
Q

Why does it only go one direc’on? Why doesn’t it go backwards?

A

Aler Na+ flows in and makes the inside posiFve, the Na+ channels in that patch close

As I menFoned, they won’t open again for a liUle while, they have to reset.

This means that even though Na+ will diffuse in both direcFons when it enters, it can only open channels that haven’t recently opened

44
Q

Action Potentials were first studied in what

A

giant squid; Loligo

45
Q

which scientists did work on the action potential

A

Hodgkin and Huxley working in Woods Hole MassachuseUs did a lot of measurements to figure out how the acFon potenFal works

46
Q

why was the big axon important to the scientists

A

A big axon was important to them because it was easy to work with (electrodes!)
A big axon is important to the squid because it conducts the action potential faster than an axon of a smaller diameter
In the squid, these giant axons convey signals for things like critical reflexes–for times when the information needs to get to the muscles quickly

47
Q

why is a small axon more efficient

A

This is more efficient: there are fewer channels to open and reset, there are fewer pumps that need to be involved, etc. Basically, it makes the Na+ that you let in more effective

But, there’s only so efficient we can make the system this way
you can only fit so many GIANT axons into a brain before it becomes unwieldy and expensive
that would limit the number of cells and connections that you could have

48
Q

So evoluFon determined a way to get the same increase in the ability of the axon to hold and spread charge but in a small axons– what is it

A

myelination

49
Q

what is myelination

A

In many vertebrates, axons are wrapped by other cells (known as Schwann cells) this insulates the axon, preventing Na+ and K+ from leaking out or in
enables the cell to hold the charge for longer
i.e. the positive charge from the influx of Na+ can travel farther down the axon

50
Q

adding myelin is equivalent to doing what to the diameter

A

increasing

they both make the action potential faster and more efficient

51
Q

does myelin coat the entire axon

A

no
Rather, there are many Schwann cells, that wrap the axon
In between those cells are what are called “nodes of ranvier”

52
Q

what are at the nodes of ranvier

A

there are lots and lots (and lots) of channels and pumps

53
Q

how do nodes or ranvier help

A

This means that instead of having to open channels along every micron of the axon
The acFon potenFal can “skip” rapidly from one node to the next, regeneraFng just at the nodes instead of at all of the areas in between

54
Q

what is Multiple Sclerosis

A

Multiple Sclerosis is an autoimmune disease that results in damage to and breakdown of the myelin

As a consequence, paFents exhibit impaired movements and other deficits because signals are no longer travelling quickly or efficiently

55
Q

give a summary of action potential thus far

A

the action potential is an electrochemical wave, driven by the movement of ions along their electrical and concentraFon gradients
this means that we can measure it by measuring the voltage and manipulate it either by altering the chemistry or by altering the voltage

The acFon potenFal is an electrochemical wave, driven by the movement of ions along their electrical and concentraFon gradients SScan measure it (with electrodes) SSmanipulate it either by altering the chemistry or by altering the voltage

It is an “allJorJnone” signal
Once it’s started, once you nudge the first domino, it will conFnue down the length of the axon without decreasing in size or strength This is because it gets regenerated over and over again along the way

It takes energy
Aler an acFon potenFal occurs, energy is used to put all the pieces back into the right spot (move K+ back in, Na+ back out)

56
Q

as code, what is the action potential represented as

A

This means that as a code, we basically have 0s and 1s, the acFon potenFal is on or off

57
Q

why is the 1 and 0’s a problem

A

But there are also many instances where you need more complexity

U0 Biology 115 (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions