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Biology > Nervous coordination and muscles > Flashcards

Nervous coordination and muscles Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What’s specialised about neurone membranes?

A

Sodium-Potassium pumps actively transport Na+ out of the cell and K+ into the cell
Sodium and potassium channels allow facilitated diffusion in either direction

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2
Q

What is the resting potential of a neurone?

A

The potential difference across the neurone membrane while the neurone is at rest

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3
Q

What is the avg value of resting potential?

A

-60 to -70 mV inside the neurone compared with outside

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4
Q

Why is a neurone more negative inside than outside?

A

3Na+ ions are pumped out for every 2K+ ions pumped into it and channels are kept closed

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5
Q

What is an action potential?

A

Depolarisation of the neurone membrane so that the inside is more positive than the outside

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6
Q

What is the value of the action potential?

A

+40mV

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7
Q

When does depolarisation occur?

A

When sodium channels open in response to a stimulus

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8
Q

What happens in an action potential?

A

Sodium ions diffuse into the neurone to start a nerve impulse

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9
Q

How do receptor cells work?

A

A stimulus causes the membranes to become more permeable to sodium ions so that the inside becomes less negative (generator potential)

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10
Q

What must happen for an action potential to be triggered?

A

A threshold level must be reached (-50mV) by the stimulus

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11
Q

What does the action potential trigger?

A

Nerve impulse

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12
Q

What happens in repolarisation?

A

Sodium channels close and potassium channels open, the neurone repolarises

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13
Q

What does it mean when a neurone is hyperpolarised?

A

Potassium channels are too slow to close and the potential difference overshoots, making it more negative inside than resting potential

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14
Q

How do neurones recover from hyperpolarisation?

A

Sodium-Potassium pumps restore resting potential

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15
Q

What happens in the refractory period?

A

Sodium ion channels can not reopen after they have been activated, until resting potential is reestablished

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16
Q

What does the refractory period ensure?

A

The movement of the impulse is unidirectional, meaning that it will only travel forwards and not backwards, also stops many impulses sent at once

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17
Q

How do nerve impulses transmit across a neurone?

A

Increasing sodium to depolarisation sets up a local current, the sodium diffuses sideways, this causes sodium ions further down the neurone to open, setting off another action potential, the local current moves down the neurone as a wave of depolarisation

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18
Q

What does the myelin sheath do?

A

Prevents ions from reaching the axon

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19
Q

Where can ions enter the axon?

A

Nodes of Ranvier

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20
Q

What does the cell body of the myelinated neurone do?

A

Protein production and neurotransmitter production

21
Q

What do dendrites do?

A

Carry action potentials to surrounding cells

22
Q

What does the axon do?

A

Carry nervous impulse along the neurone

23
Q

What is the myelin sheath made of?

A

Individual Schwann cells

24
Q

What are the gaps between Schwann cells called?

A

Nodes of Ranvier

25
Q

How are action potentials transmitted down a non-myelinated neurone?

A

When depolarisation occurs, voltage-gated sodium channels open further down the axon and by the time depolarisation has spread part of the neurone has already repolarised

26
Q

What is saltatory conduction?

A

Action potentials “jump” from node to node , which is much quicker, in myelinated neurones when transmitting an action potential

27
Q

What is the difference between the synapse and synaptic cleft?

A

The synapse is the junction between two neurones, whereas the synaptic cleft is the gap that separates the pre and post synaptic neurone

28
Q

What is the synaptic knob?

A

Swelling at the end of pre-synaptic neurones which makes and releases neurotransmitters

29
Q

What is a neurotransmitter?

A

A chemical that diffuses across the synaptic cleft, to transmit a signal to the post synaptic neurone (cell signalling)

30
Q

What is acetylcholine?

A

A type of neurotransmitter

31
Q

What is a cholinergic synapse?

A

A synapse which makes and releases acetylcholine

32
Q

What type of channels are on the pre and post synaptic neurones at the synapse?

A

Pre: calcium
Post: sodium

33
Q

What is step 1 at the synapse?

A

Nerve impulse arrives at synaptic knob, causing calcium channels to open, which move into the knob by facilitated diffusion, these ions cause vesicles containing acetylcholine to migrate towards the pre-synaptic membrane

34
Q

What is step 2 at the synapse?

A

Acetylcholine vesicles fuse with the membrane and release acetylcholine into the synaptic cleft by exocytosis, they diffuse quickly across the cleft due to the short distance

35
Q

What is step 3 at the synapse?

A

Acetylcholine bind to receptor sites at post-synaptic neurones, causing sodium channels to open, causing depolarisation and a nerve impulse is set up

36
Q

What is step 4 at the synapse (now post-synaptic neurone)?

A

Acetylcholinesterase is released, acetylcholine is hydrolysed to acetyl and choline, which diffuse back to the pre-synaptic neurone and are recycles with ATP, sodium channels close and the post-synaptic neurone is repolarised

37
Q

What do excitatory transmitters do?

A

Cause depolarisation on the post-synaptic neurone to create an action potential

38
Q

What do inhibitory transmitters do?

A

Cause hyperpolarisation, preventing the formation of a new action potential (GABA)

39
Q

What can too much excitation lead to?

A

Seizures and other neurological disorders

40
Q

What can too much inhibition lead to?

A

Depression and other mood disorders

41
Q

How are weak stimuli amplified?

A

Temporal summation and spatial summation

42
Q

What is temporal summation?

A

When multiple messages are sent quickly from the same pre-synaptic neurone

43
Q

What are skeletal muscle fibres made up of?

A

Myofibrils

44
Q

What are sarcoplasms?

A

Individual muscle cells that make up myofibrils

45
Q

What are myofibrils made up of?

A

Repeating units called sarcomeres

46
Q

What are the regions of myofibrils?

A

H zones, I bands, A band, the M line and the Z discs

47
Q

What proteins are sarcomeres made up of?

A

Actin (thin) and myosin (thick) proteins which form filaments

48
Q

What si trop

A
49
Q
A

Biology (22 decks)

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