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AQA A2 BIOLOGY 2015+ > 6 Nervous coordination and muscles > Flashcards

6 Nervous coordination and muscles Flashcards

1
Q

What are the two main forms of coordination in animals?

A

The nervous system

The hormonal system

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2
Q

Give an example of nervous coordination

A

Reflex action e.g withdrawal of hand from an unpleasant stimulus

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3
Q

Give an example of hormonal coordination

A

The control of blood glucose concentration

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4
Q

What are neurones?

A

Specialised cells adapted to rapidly carrying nerve impulses from one part of the body to another

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5
Q

What is a mammalian motor neurone made up of?

A

Cell body, dendrons, Schwann cells, myelin sheath and nodes of Ranvier.

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6
Q

What do Schwann cells do?

A

They surround the axon, protecting it and provide electrical insulation

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7
Q

What are noses of Ranvier?

A

Constrictions between adjacent Schwann cellswhere there is no myelin sheath

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8
Q

What are the different types of neurones?

A

Sensory neurones, motor neurones and relay neurones

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9
Q

What is the function of the sensory neurone?

A

It transmits nerve impulses from a receptor to a motor or relay neurone

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10
Q

What is the function of a motor neurone?

A

It transmits nerve impulses from a relay neurone to an effector

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11
Q

What is the function of a relay neurone?

A

It transmits impulses between neurones

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12
Q

What is a nerve impulse?

A

A wave of electrical activity that travels along the axon membrane

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13
Q

What prevents the sodium and potassium ions from diffusing across the axon plasma membrane?

A

The phospholipid bilateral of the axon plasma membrane

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14
Q

By what process do sodium and potassium ions pass through ion gates channels?

A

Facilitated diffusion

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15
Q

What is the resting potential value in humans?

A

-65mV

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16
Q

What is the role of the sodium potassium pump?

A

Actively transport sodium ions out of the axon.

Actively transport potassium ions into the axon.

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17
Q

What is the threshold that needs to be reached in order to create an action potential?

A

+40mV

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18
Q

What is resting potential?

A

The difference in electrical charge maintained across the membrane of the axon of a neurone when not stimulated

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19
Q

What is repolarisation?

A

Return to the resting potential in the axon of a neurone after an action potential

20
Q

Does the size of an action potential ever change?

A

No, it remains the same from one end of the axon to the other

21
Q

Why does an action potential pass along a myelinated neurone faster than an unmyelinated neurone?

A

Because in an unmyelinated neurone, the events of depolarisation have to take place all the way along an axon and this takes more time.

22
Q

What factors affect the speed at which an action potential travels?

A

Myelin sheath, diameter of the axon and temperature.

23
Q

What is saltatory conduction?

A

When an action potential jumps from one node of Ranvier to another.

24
Q

How can an organism perceive the size of a stimulus?

A

By the number of impulses passing in a given time.

By having different neurones with different threshold values

25
Q

What is the refractory period?

A

The period during which the membrane of the axon of a neurone can’t be depolarised and no new action potential can be initiated.

26
Q

What are the three purposes of the refractory period?

A

It ensures that action potentials are propagated in one direction only.
It produces discrete impulses.
It limits the number of action potentials.

27
Q

What is a synapse?

A

A junction between neurones, in which they have a narrow gap, the synaptic cleft, which a neurotransmitter can pass.

28
Q

What is a presynaptic neurone?

A

The neurone that releases the neurotransmitter

29
Q

What organelles does the synaptic knob possess?

A

Many mitochondria and large amounts of endoplasmic reticulum

30
Q

What are these organelles required for?

A

They are required in the manufacture of the neurotransmitter which takes place in the axon.

31
Q

Where is the neurotransmitter stored?

A

In the synaptic vesicles

32
Q

What are the features of the synapse?

A

Undirectionality - synapses can only pass information in one direction, from the presynaptic neurone to the postsynaptic neurone.
Summation - a rapid build up of neurotransmitter in the synapse.

33
Q

What are the two types of summation?

A

Spatial summation

Temporal summation

34
Q

What is spatial summation?

A

When a number of different presynaptic neurones together release enough neurotransmitter to exceed the threshold value of the post synaptic neurone.

35
Q

What is temporal summation?

A

When a single presynaptic neurone releases neurotransmitter many times over a short period of time in order to exceed the threshold value.

36
Q

What are inhibitory synapses?

A

Synapses that make it less likely that a new action potential will be created on the post synaptic neurone.

37
Q

What is a cholinergic synapse?

A

A synapse in which the neurotransmitter is a chemical called acetylcholine.

38
Q

Where do cholinergic synapses occur?

A

Central nervous system

Neuromuscular junctions

39
Q

What are the three types of muscle in the body?

A

Cardiac muscle
Smooth muscle
Skeletal muscle

40
Q

What are myofibrils?

A

Tiny muscle fibres that individual muscles are made of

41
Q

Which two types of protein filament are myofibrils made of?

A

Actin and Myosin

42
Q

What is a sarcomere?

A

The distance between adjacent Z-lines

43
Q

What is tropomyosin?

A

An important protein found in muscle, which forms a fibrous strand around the action filament.

44
Q

What types of muscle fibre are there?

A

Slow-twitch fibres

Fast-twitch fibres

45
Q

What is a neuromuscular junction?

A

The point where a motor neurone meets a skeletal muscle fibre

46
Q

What is the sliding filament mechanism?

A

The process where actin and myosin filament slide past one another.

AQA A2 BIOLOGY 2015+ (11 decks)

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