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BIOLOGY A LEVEL > TOPIC 6B > Flashcards

TOPIC 6B Flashcards

1
Q

Describe the resting potential of a neurone.

A

(see page 136 in the revision guide)

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2
Q

Describe the action potential of a neurone.

A

(see page 136 in the revision guide)

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3
Q

What is hyper polarisation of a neurone?

A

Potassium ion channels are slow to close so there’s. a slight ‘overshoot’ where too many potassium ions diffuse out of the neurone.
The potential difference becomes more negative than the resting potential (e.g. less than -70mV)

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4
Q

What is the resting potential of a neurone?

A

The ion channels are reset. The sodium-potassium pump return the membrane into its resting potential and maintains it until the membrane is excited by another stimulus.

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5
Q

What is the refractory period?

A

After an action potential, the neurone cell membrane can’t be excited again straight away. This is because the ion channels are recovering and they can’t be made to open - sodium ion channels are closed during depolarisation and potassium ion channels are closed during hyper polarisation.

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6
Q

How does a wave of depolarisation occur in a neurone?

A

(see page 137 in the revision guide)

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7
Q

What 3 things does a refractory period do to an action potential in a neurone?

A

(see page 137 in the revision guide)

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8
Q

Read the purple box on page 137 in the revision guide.

A

understand?

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9
Q

What 3 factors affect the speed of conduction of action potentials across a neurone?

A
  1. Myelination
  2. Axon diameter
  3. Temperature
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10
Q

Why does myelination affect the speed of conduction of action potentials across a neurone?

A

(see page 138 in the revision guide)

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11
Q

Why does the axon diameter affect the speed of conduction of action potentials across a neurone?

A

(see page 138 in the revision guide)

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12
Q

Why does temperature affect the speed of conduction of action potentials across a neurone?

A

(see page 138 in the revision guide)

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13
Q

What is a synapse?

A

A synapse is the junction between a neurone and another neurone or between a neurone and an effector cell, e.g. a muscle or gland cell.

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14
Q

Draw the structure of a motor neurone.

A

(see page 138 in the revision guide)

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15
Q

Describe how one neurone can trigger an action potential in another neurone.

A

(see page 139 in the revision guide)

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16
Q

Describe how a nerve impulse is transmitted across a cholinergic synapse.

A

(see page 139 in the revision guide)

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17
Q

What do excitatory neurotransmitters do?

A

(see top of page 140 in the revision guide)

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18
Q

What do inhibitory neurotransmitters do?

A

(see top of page 140 in the revision guide)

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19
Q

What is summation?

Name the two types of summation.

A

Summation is where the effect of neurotransmitter released from many neurones (or one neurone that’s stimulated a lot in a short period of time) is added together.

  • spatial summation
  • temporal summation
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20
Q

Describe spatial summation.

A

(see page 140 in the revision guide)

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21
Q

Describe temporal summation.

A

(see page 140 in the revision guide)

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22
Q

What is a neuromuscular junction?

A

A neuromuscular junction is a synapse between a motor neurone and a muscle cell.

23
Q

What neurotransmitter do neuromuscular junctions use?

A

Acetylcholine (ACh)

Which binds to cholinergic receptors called nicotinic cholinergic receptors.

24
Q

What are the few differences between how neuromuscular junctions work instead of how synapses work?

A

(see bottom of page 140 in the revision guide)

25
Q

What are 5 ways drugs can affect synaptic transmission?

A

(see page 141 in the revision guide)

26
Q

What do skeletal muscles do and where are they found?

A

Skeletal muscle (also called striated, striped or voluntary muscle) is the type of muscle you use to move. e.g. the biceps and triceps move the lower arm.

Skeletal muscle are attached to bones by tendons.

Pais of skeletal muscles contract and relax to move bones at a joint. The bones of a skeleton are incompressible (rigid) so they act as levers, giving the muscles something to pull against.

27
Q

What do ligaments do?

A

Ligaments attach bones to other bones, to hold them together.

28
Q

What are muscles that work together to move a bone called?

A

Antagonistic pairs

The contracting muscle is called the agonist and the relaxing muscle is called the antagonist.

29
Q

Explain how triceps and biceps both work as an antagonist pair to move your arm up and down.

A

(see page 142 in the revision guide)

30
Q

What is the cell membrane of muscle fibres called?

A

The cell membrane of muscle fibres is called sarcolemma.

31
Q

What is the muscle cell’s cytoplasm called?

A

The cytoplasm of a muscle cell is called the sarcoplasm.

32
Q

What do transverse (T) tubules do?

A

They help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre.

33
Q

Where is the sarcoplasm reticulum and what does it do?

A

A network of internal membranes called the sarcoplasm reticulum runs through the sarcoplasm.

The sarcoplasm reticulum stores and releases calcium ions that are needed for muscle contraction.

34
Q

How are muscle fibres adapted for their function?

A

Muscle fibres have lots of mitochondria to provide ATP for muscle contraction.

Muscle fibres are multinucleate (contain many nuclei)

Muscle fibres have lots of long, cylindrical organelles. called myofibrils. They’re made up of proteins which are highly specialised for contraction.

35
Q

Draw and label the structure and components of a muscle.

A

(see page 142 in the revision guide)

36
Q

Where are myofilaments found in a muscle?

A

In the myofibrils.

Myofilaments are thick or thin that move past each other to make the muscle contract.

37
Q

What protein is thick myofilaments made out of?

A

Myosin.

38
Q

What protein is thin myofilaments made out of?

A

Actin.

39
Q

What are A-bands?

A

In the myofibrils there are myofilaments, Actin or myosin.

The A-band seen under the microscope contain thick myosin filaments and some overlapping thin actin filaments.

40
Q

What are I-bands?

A

In the myofibrils there are myofilaments, Actin or myosin.

The I-band seen under the microscope contain thin actin filaments only.

41
Q

What is a sarcomere?

A

They are many short units of myofibrils.

They are marked off at the end with a Z line.

42
Q

What is an M-line?

A

The middle of each sarcomere.

43
Q

What is the H-zone?

A

In the myofibrils there are myofilaments, Actin or myosin.

The H-zone seen under the microscope contain myosin filaments only.

44
Q

Draw an example of a sarcomere.

A

(see page 143 in the revision guide)

45
Q

Describe the sliding filament theory as an explanation for muscle contraction.

A

(see page 143 in the revision guide)

46
Q

What are the components on myosin and actin filaments adapted for muscle contraction?

A

Myosin filaments:

  • Globular heads that are hinged to move back and forth.
  • Binding site for actin
  • Binding site for ATP

Actin filaments:
- Binding site for myosin heads, called actin-myosin binding sites

Another protein called tropomyosin is found been actin filaments, it helps myofilaments to move past each other

(see page 144 in the revision guide for a diagram)

47
Q

Describe what is happening in the muscle filaments when a muscle is relaxed.

A

(see page 144 in the revision guide)

48
Q

Describe what is happening in the muscle filaments when a muscle is contracting.

A

(see page 144 in the revision guide)

49
Q

What 3 main ways is ATP synthesised for muscle contraction?

A

1) Aerobic respiration
2) Anaerobic respiration
3) ATP-Phosphocreatine (PCr) system

50
Q

Describe how ATP is synthesised in ATP-Phosphocreatine (PCr) system.

A

(see page 145 in the revision guide)

51
Q

List 6 properties of slow twitch muscle fibres.

A

(see page 145 in the revision guide)

52
Q

List 6 properties of fast twitch muscle fibres.

A

(see page 145 in the revision guide)

53
Q

Describe using the sliding filament theory, how a muscle contracts.

A
  • Z lines come closer together
  • I bands narrower
  • H bands narrower
  • A bands stay the same

This is called interdigitation of. the actin and myosin filaments.

BIOLOGY A LEVEL (19 decks)

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