C2.2 Neural signalling SL

0.0(0)
studied byStudied by 0 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/62

encourage image

There's no tags or description

Looks like no tags are added yet.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

63 Terms

1
New cards

Neurons

Cells within the nervous system that carry electrical impulses

  • Nerve cells

2
New cards

Nerve impulse

Electrical signal passed betw 2 cells

  • Can pass along / between neurons

3
New cards

Electric impulse (double check)

Movement of positively charged ions across the axon

4
New cards

2 groups of nerve impulses

  • Transmission ALONG neurons

  • Transmission BETWEEN neurons

5
New cards

What makes up the cell body of a neuron?

  • Cytoplasm

  • A nucleus

  • Elongated nerve fibres of varying length projecting from it

<ul><li><p>Cytoplasm</p></li><li><p>A nucleus</p></li><li><p>Elongated nerve fibres of varying length projecting from it</p></li></ul><p></p>
6
New cards

Axon

A long single fibre

7
New cards

Dendrites

Multiple shorter nerve fibres

8
New cards

What are electrical impulses conducted along?

Axons + dendrites

9
New cards

What do receptors do to stimuli?

Convert stimuli into electrical signals

10
New cards

What do effectors do to electric signals?

Convert the electrical signals into a response

11
New cards

3 types of neurons

  1. Sensory

    • send impulses to the CNS

  2. Motor

    • send impulses from the CNS

  1. Relay

    • send impulses within the CNS

12
New cards

Membrane potential

Voltage created by an imbalance of charges (ions) on either side of the membrane

  • Either relatively positive or negative

13
New cards

Resting membrane potential

-70mV

  • Inside of neuron relatively negative

  • When the neuron is at rest

14
New cards

Location of sodium + potassium ions during resting membrane potential

  • Na ions outside the cell

  • K ions inside

15
New cards

What generates the resting potential?

Pumping → to establish + maintain concentration gradients of Na + K ions

16
New cards

How does the sodium-potassium pump generate the resting potential?

Energy from ATP drives the pumping of Na + K ions in opposite directions across the plasma membrane of neurons

  • Actively transports Na ions to the outside + K ions to the inside of the cell

  • Need ATP to generate a CG

17
New cards
<p>Why is resting potential negative? <em>(double check)</em></p>

Why is resting potential negative? (double check)

3 Na+ leave the cell, but only 2 K+ enter → more positively charged ions leaving → interior of cell relatively negative to outside

18
New cards

3 things that maintain resting potential?

  1. Sodium-potassium pumps: 3 Na+ out, 2 K+ in via AT

  2. Leakage of K+ ions back across the

    membrane by facilitated diffusion

  3. Negatively charged ions (Cl-) fixed inside the axon

19
New cards

Is a nerve impulse electrical or chemical?

Electrical

20
New cards

Why is a nerve impulse electrical?

Involves movement of positively charged ions

21
New cards

Membrane polarization (DOUBLE CHECK DEFINITION)

The difference in electrical charge across the cell membrane, where the inside of the cell is more negative than the outside (resting potential)

  • Imp for generating action potentials during nerve impulse transmission

22
New cards

Depolarization

Membrane potential goes from negative to positive

  • Due to movement of postitive ions (Na+ moving into the cell)

  • Change from resting to action potential

23
New cards

Repolarization

Membrane potential goes from positive back to negative

  • Due to movement of positive ions (K+ moving out of the cell)

  • Action → resting potential

24
New cards
<p>Steps of nerve transmission + establishing resting potential</p>

Steps of nerve transmission + establishing resting potential

  1. Voltage-gated Na ion channels open

  2. Na ions diffuse into the cell (facilitated diffusion)

  3. Causes depolarisation (- to +)

    • Bc Na ions = positively charged

  4. Inside relatively positive → voltage-gated Na ion channels close + voltage-gated K ion channels open

  5. K ions diffuse out of the cell (facilitated diffusion)

  6. Repolarisation (+ to -)

    • Inside of cell relatively negative

  7. BUT at this point, K+ outside, Na+ inside → needs to be other way

  8. Sodium potassium pump re-establishes resting potential by actively pumping Na ions out + K in

25
New cards

idk

1. The sodium-potassium pump binds to three sodium ions from

the intracellular side of the membrane.

2. The sodium-potassium pump is phosphorylated using a

phosphate from ATP.

3. The sodium-potassium pump changes shape and moves the

sodium ions to the extracellular side.

4. The sodium-potassium pump can now bind to two potassium

ions.

5. The potassium ions are released into the intracellular side.

6. The phosphate is released, and the sodium-potassium pump

reverts back to its original shape.

7. This is an example of active transport as the sodium and

potassium ions are being moved against their concentration

gradient.

8. As a result, there are more sodium ions outside the

membrane and more potassium ions inside the membrane.

9. However, movement of potassium ions is reduced as they are

attracted to other native anions inside the axon.

10. This means that there is an electrochemical gradient

established.

11. Some potassium ion channels are open so some potassium

ions can diffuse through the membrane from inside to outside.

12. Sodium ion channels are not open, so no sodium ions can

diffuse through the membrane from outside to inside.

13. Therefore, overall, there is a more negative charge inside the

cell, and the resting potential is established (~70 mV).

26
New cards

Action potential

The potential electrical difference produced across the axon membrane when a neuron is stimulated

  • Involves rapid movement of Na ions + K ions across the membrane of the axon

  • 2 stages- depolarisation + repolarisation

27
New cards

Nerve impulses in relation to action potentials

Nerve impulses = action potentials that are propagated along nerve fibres

28
New cards

Feature of nerve impulses related to propogation

Self propagating

29
New cards

Self-propagating

Depolarisation in 1 part triggers depolarization in the next part (along the axon) due to the opening of voltage-gated channels

30
New cards
<p>How many directions does nerve transmission happen in?</p>

How many directions does nerve transmission happen in?

1

  • Start: dendrite

  • Moves along axon

  • End: exon terminal

31
New cards

When is a neuron membrane said to be polarised?

Once resting potential is reached

32
New cards

What needs to happen to the neuron membrane to initiate a nerve impulse in a neuron?

Neuron membrane needs to be depolarised

  • Reversal of the electrical potential difference across the membrane

33
New cards

When does the depolarisation of the membrane occur?

When an action potential is generated

34
New cards

Average speed for nerve impulse

1 m/s

35
New cards
<p>Adaptations to increase the speed of nerve impulses </p>

Adaptations to increase the speed of nerve impulses

  1. Increase axon diameter

  2. Myelination

Factors affecting speed of nerve impulses

36
New cards

Space in between the myelin sheath

Nodes

<p>Nodes</p>
37
New cards
<p>How do myelin sheaths increase the speed of nerve impulses?</p>

How do myelin sheaths increase the speed of nerve impulses?

  1. They insulate the electrical charge

  2. Electrical charge only jumps at nodes (Na+ in and out, K+ in and out only at nodes)

  3. So less energy needed (to power Na K pump) + increases speed

38
New cards

Compare the speed of transmission in giant axons of squid and smaller non-myelinated nerve fibres

knowt flashcard image
39
New cards

Also compare the speed of transmission in myelinated + non-myelinated fibres

knowt flashcard image
40
New cards

APPLICATION OF SKILLS

Students should be able to describe negative and positive correlations and apply correlation coefficients as a mathematical tool to determine the strength of these correlations.

Students should also be able to apply the coefficient of determination (R2 ) to evaluate the degree to which variation in the independent variable explains the variation in the dependent variable.

41
New cards
  1. Conduction speed of nerve impulses is … correlated with animal size

  2. Conduction speed of nerve impulses is … correlated with axon diameter.

  1. Negatively

  2. Positively

42
New cards

Synapse

Junctions betw:

  • Neurons

  • Neurons + effector cells

Here signals are passed by chemical neurotransmitters

<p>Junctions betw:</p><ul><li><p>Neurons </p></li><li><p>Neurons + effector cells</p></li></ul><p></p><p>Here signals are passed by chemical neurotransmitters</p>
43
New cards

Across a typical synapse, how many directions can a signal pass in?

1

44
New cards

2 main steps of synaptic transmission (transmission between neurons)

  1. Release of neurotransmitters from a presynaptic membrane

  2. Generation of an excitatory postsynaptic potential

45
New cards
<p>Steps of transmission between neurons- synaptic transmission (part 1, presynaptic neuron)</p>

Steps of transmission between neurons- synaptic transmission (part 1, presynaptic neuron)

  1. Action potential reaches the end of the presynaptic neuron

  2. Voltage gated calcium ion channels open

  3. Ca ions enter the preS neuron via facilitated diffusion

    • Bc high conc of Ca ions outside

  4. Ca ions force vesicles with neurotransmitters to fuse with the membrane

  5. Neurotransmitters are released into the synapse (exocytosis)

46
New cards
<p>Steps of transmission between neurons- synaptic transmission (part 2, postsynaptic neuron)</p>

Steps of transmission between neurons- synaptic transmission (part 2, postsynaptic neuron)

  1. Neurotransmitters diffuse across the synapse

  2. Binds to complementary receptor on the postS membrane

  3. Na ion channels open

  4. Na ions enter postS neuron via facilitated diffusion

  5. If enough ions enter the postS cell → generates an action potential

  6. Neurotransmitter removed from synapse

47
New cards

Why do neurotransmitters need to be removed from the synapse?

Prevents constant stimulation of the post-synaptic cell + an excessive firing of action potential

48
New cards

From spec

  1. Uptake of calcium in response to depolarization of a presynaptic membrane

  2. It is a signalling chemical inside a neuron

  3. Neurotransmitters diffuse across the synaptic cleft

  4. Binding to transmembrane receptors

49
New cards

Acetylcholine

Neurotransmitter betw motor neurons + muscles

50
New cards

Examples of synapses where the neurotransmitter acetylcholine exists

Neuromuscular junction

51
New cards

class work

52
New cards

Importance of synapses + why is this beneficial?

Ensures 1 way transmission of impulses

  • Prevents impulses from travelling the wrong way

53
New cards

How do synapses ensure 1 way transmission

Neurotransmitter is released on 1 side + its receptors are on the other

54
New cards

Explain fully how a resting potential is generated in a neurone.

knowt flashcard image
55
New cards

explain the principles of synaptic transmission

8 marks

<p>8 marks</p>
56
New cards

explain synaptic transmission- gapfill on phone

57
New cards

Enzyme ACHesterase breaks down ACH into acetyl + choline

Choline reabsorbed by the presynaptic neuron to make more acetyl choline

58
New cards

ACH esterase breaks down / destroys neurotransmittor after action potential is generated in the post synaptic neuron

59
New cards
60
New cards
61
New cards
62
New cards
63
New cards