Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A Level Biology > Topic 6B - Nervous Coordination > Flashcards

Topic 6B - Nervous Coordination Flashcards

1
Q

How is the movement of sodium and potassium ions maintained? What type of transport do they use?

A

Sodium-potassium pump - active transport
Potassium ion channels - facilitated diffusion

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

Why is the membrane polarised?

A

There is a difference in charge across the membrane

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

What do sodium potassium pumps do? How does it transport it?

A

Use active transport
Move 3 sodium ions out of the neurone for every 2 potassium ions moved in, using ATP.

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

What do potassium ion channels do?

A

Allow facilitated diffusion of potassium ions out of the neurone down the concentration gradient.

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

How is a sodium ion electrochemical gradient produced?

A

Membrane isn’t permeable to sodium ions so cant diffuse back in
More positive Na+ outside of cell than inside

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

Why do potassium ions diffuse back out through the ion channels?

A

Most channels open at rest
Membrane is more permeable

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

What is an action potential?

A

Rapid change in potential difference, cell becomes depolarised

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

What are the 5 stages of an action potential?

A

Stimulus
Depolarisation
Repolarisation
Hyperpolarisation
Resting potential

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

What happens during the stimulus?

A

Cell membrane excited, causing Na channels to open
Membrane permeable to sodium
Sodium diffuse down sodium electrochemical gradient
Inside of neurone less negative

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

What happens during depolarisation?

A

If potential difference reaches threshold, more Na channels open
More Na diffuse into neurone causing depolarisation

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

What happens during repolarisation?

A

Sodium ions channels close and potassium ion channels open
K+ ions diffuse down conc gradient
Begins getting the membrane back to resting potential

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

What happens during hyperpolarisation?

A

K+ channels slow to close
A few too many K + ions diffuse out of neurone
Potential difference becomes more negative than resting potential

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

What happens during the resting potential?

A

Ion channels are reset
NaK+ pump returns membrane to resting potential
Does this by pumping Na+ out and K+ in
Maintains resting potential until membrane is excited again

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

What is the refractory period?

A

Time delay between action potentials
So they dont overlap but pass along as discrete impulses
Potentials are unidirectional and are all closed at the same time

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

What causes waves of depolarisation?

A

Some Na ions diffuse sideways into neurone
This causes Na ions in next channel of the neurone to open and Na ions diffuse into that part

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

Why do the waves move away from the parts of the membrane in the refractory period?

A

These parts cant fire an action potential

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

What is the all or nothing principle?

A

Once the threshold is reached, an action potential will be fired
(Always fires with the same change in voltage, no matter how big the stimulus is)

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

What will a bigger stimulus cause?

A

More action potentials to occur

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

What does the myelin sheath do?

A

Electrical impulse insulator

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

What is the sheath made of in the PNS?

A

Schwann cells

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

What is between the myelin sheath? What does it do?

A

Nodes of ranvier
Where sodium ion channels are concentrated

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

Where does depolarisation occur in Saltatory conduction?

A

At the nodes of ranvier

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

How does an impulse travel in a non-myelinated neurone?

A

Impulse a travels as a wave along a whole length of the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does axon diameter affect conduction?

A

Bigger diameter conduction will work better as there is less resistance
Depolarisation reaches other parts quicker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How does temperature affect conduction?
Conduction increases and ions diffuse faster To an extent - denature at over 40C
26
What is a synapse?
The junction between the neurone membrane and another and an effector cell
27
What is the synaptic cleft
Gap between syanpses
28
What is the swelling on the presynaptic neurone called?
The synaptic knob
29
What does the synaptic knob contain?
Vesciles filled with neurotransmitters
30
What happens at the end of an action potential?
Neurotransmitters are released into the synaptic cleft and diffuse across and attach to the receptor cells on the post synaptic membrane
31
What do receptors only on the postsynaptic membrane do?
Make sure impulses are unidirectional Remove neurotransmitters so response doesn’t keep happening
32
What does acetylecholine do?
Binds to cholinergic receptors
33
What happens after the arrival of the action potential? (Cholinergic synapse)
Arrives at presynaptic membrane Stimulates voltage-gated Ca ion channels to open Ca diffuse into synaptic knob
34
What occurs during the fusion of vesicles?
Influx of Ca ions Causes synaptic knob to fuse with the presynaptic membrane Release ACh into synaptic cleft - via exocytosis
35
How does ACh diffuse?
Diffuses across cleft and binds to specific cholinergic receptors on postsynaptic membrane Na channels open
36
Why is ACh removed?
To stop the response continuing happening
37
What does the exciters do?
Polarise postsynaptic membrane, firing an action potential
38
What does inhibitory do?
Hyperpolarise postsynaptic membrane, preventing an action potential from being fired
39
What is inhibitory synapse?
Where an inhibitory neurotransmitter is released, following an action potential
40
What is summation?
Where the effect of neurotransmitters released from meant neurones is added together
41
What is spatial summation?
2 or more presynaptic neurones release their neurotransmitter on the same post synaptic neurone
42
What is temporal summation?
2 or more nerve impulses arrive in quick succession from the same presynaptic neurone
43
What do neuromuscular junctions do?
Use acetylcholine which binds to chollinergic receptors called nicotine cholinergic response
44
What’s the difference between neuromuscular junctions and cholinergic synapses?
Post synaptic membrane has lots of folds that form clefts and store AChE Has more receptors than other synapses Always excitatory, so when a motor neurone fires an action potential, it normally triggers a response in a muscle cell
45
Why do some drugs block receptors?
So fewer receptors are activated
46
Why do some drugs block enzymes?
Less neurotransmitter broken down so that more in the cleft can bind to the receptors and are there for longer
47
Why do some drugs stimulate the release of neurotransmitter?
So more receptors can be activated
48
Why do some drugs inhibit the release of neurotransmitter?
To the fewer receptors are activated
49
What is smooth muscle?
Contracts without conscious control
50
What is cardiac muscle?
Contracts without conscious control Only found in heart
51
What is skeletal muscle?
Muscle used to create movement
52
How do skeletal muscles work?
Bones of skeleton are incompressible, so they act as levers giving the muscles something to pull
53
What is antagonistic pair?
A pair of muscles that work together to move a bone
54
What are the cell membranes of skeletal muscles called?
Sarcolemma
55
What are the folds in skeletal muscles called? What do they do?
Transverse tubules Help spread electrical impulses throughout the sacroplasm to reach all parts of the muscle fibre
56
What does sacroplasmic reticulum do?
Network of internal membranes that store and release Ca ions needed for muscle contraction
57
What are some qualities of muscles fibres?
Lots of mitochondria Multinucleate Myofibrils - made of protein highly specialised for contractions
58
What do muscles look like under a microscope?
Different colours will stain different parts, the image will either be longitudinal or a transverse cross section
59
What do myofibrils contain?
Bundles of thick and thin myofilaments that move past each other to make muscles contract
60
What are thick myofibrils made of?
Myosin protein
61
What are thin myofibrils made of?
Actin protein
62
What are A bands?
Pattern of alternating dark and light bands and some overlapping actin filaments
63
What are L bands?
Only light bands - contain only the actin filament
64
What is a myofibrils made of?
Short units called sacromeres End is Z-line Middle is M-line Around the M-line is the H-zone
65
What is the sliding filament theory?
Myosin and actin filaments slide over each other to make sacromeres contract
66
What causes the actual muscle to contract?
Simultaneous contraction of lots of sacromeres means the myofibrils and muscle fibres contract
67
What happens to sacromeres as muscle relaxes?
Return to original size
68
What is a myosin filament?
Globular heads that are hinged, can move back and forth Each myosin head has a binding site for actin and a binding site for ATP
69
What is an actin filament?
Have an actin myosin binding site. Protein called tropomyosin is found between actin filaments Helps myofilaments move past each other
70
What happens to actin-myosin in resting muscle?
Binding site is blocked by tropomyosin Myofilaments can’t slide over each other as myosin heads cant bind to actin filaments
71
What happens when an action potential from a motor neurone stimulates a muscle cell?
Depolarises the sarcolemma
72
What does depolarisation cause?
Spreads down t-tubules to sacroplasmic reticulum Causes it to release calcium ions into sacroplasm In return triggers a muscle contraction
73
What happens when calcium ions bind to tropomyosin?
Causes protein to change shape Pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament
74
What happens when calcium ions bind to a protein attached to tropomyosin?
Causes protein to change shape Pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament
75
What is an actin-myosin cross bridge?
The bond formed when a myosin binds to an actin filament
76
What do calcium ions activate?
ATP hydrolase (This hydrolyses ATP into ADP and Pi to provide energy for muscle contraction)
77
What is contraction like in slow twitch muscles?
Slow, less powerful
78
What is contraction like in fast twitch muscles?
Quicker, more powerful
79
What is movement like in slow twitch muscles?
Slow and longer endurance
80
What is movement like in fast twitch muscles?
Fast, short endurance and high intensity
81
What respiration occurs in slow twitch muscles?
Aerboic
82
What respiration occurs in fast twitch muscles?
Anaerboic
83
What colour is slow twitch muscles?
Red due to myoglobin and blood vessels
84
What colour is fast twitch muscles?
White due to no myoglobin

A Level Biology (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions