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A Level PE Physiology > A2 PE Muscles > Flashcards

A2 PE Muscles Flashcards

0
Q

What are the characteristics of slow twitch oxidative fibres?

A

High capillary density - large amounts of oxygen can be supplied to respiring muscles.
High mitochondrial density - site of aerobic respiration.
High triglyceride stores - fed into Krebs cycle
High myoglobin content - transport oxygen to mitochondria

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1
Q

Which activities require the recruitment of slow twitch oxidative fibres (Type I)

A

Marathon, Long distance, endurance events

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2
Q

Slow twitch fibres have a high anaerobic capacity. True or false?

A

False

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3
Q

At what rate do slow twitch oxidative fibres fatigue?

A

Slow Rate - performing aerobically does not produce lactic acid so fatigue is delayed - also due to large aerobic capacity.

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4
Q

What is the speed of muscular contraction for slow twitch oxidative fibres?

A

Slow due to aerobic respiration.

Small motor neurone and fibres size results in slower less forceful contractions which can be sustained.

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5
Q

What is the full name of slow twitch (type I) fibres?

A

Slow oxidative fibres

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6
Q

What is the speed of contraction for fast twitch IIa fibres?

A

Moderately fast.

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7
Q

What is the full name of Fast twitch type IIa fibres?

A

Fast oxidative glycocytic fibres.

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8
Q

What force of contraction do fast twitch IIa produce?

A

High - fibres are larger than type I and can respire anaerobically.

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9
Q

What is the rate of fatigue of Fast twitch IIa?

A

High because they mostly work anaerobically which produces lactic acid and mitochondrial density isn’t very large.

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10
Q

What is the aerobic capacity of Fast twitch type IIa fibres?

A

Moderate as oxygen is still used. Still has capillary network to provide oxygen. Lower mitochondrial density required

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11
Q

What is the anaerobic capacity of Fast twitch type IIa fibres?

A

High - mostly produces energy anaerobically so needs a larger PC store and glycogen stores.

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12
Q

Anaerobic capacity of Fast twitch type IIb fibres?

A

Very high due to lots of PC and glycogen stores used in anaerobic respiration.

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13
Q

What is the aerobic capacity of Fast twitch type IIb fibres?

A

Low due to low capillary density mitochondrial density and myoglobin content, little oxygen used or required.

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14
Q

What is the full name of Fast twitch type IIb fibres?

A

Fast twitch glycolytic fibres.

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15
Q

What activities would recruit Fast twitch IIb fibres?

A

Explosive activities - sprint, weight lifting, throwing, jumping examples.

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16
Q

What is the force of contraction for Fast twitch type IIb fibres?

A

Large fibres and large neurone results in a fast and forceful contraction.

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17
Q

What is the speed of contraction for Fast twitch type IIb fibres?

A

Fastest due to large motor neurone size and anaerobic respiration.

18
Q

What is the rate of fatigue of Fast twitch type IIb fibres?

A

Very fast, due to anaerobic respiration lactic acid is produced. This causes the onset of fatigue.

19
Q

What is a myofibril?

A

Part of the muscle fibres contains sarcomeres and contractile proteins actin and myosin.

20
Q

What is a muscle fibre?

A

Is made up of many myofibrils surrounded by an endomysium.

21
Q

What is a fascicle?

A

Muscular structure made up of many muscle fibres.

22
Q

What is the muscle?

A

The largest structure which is made up of many fascicles.

23
Q

What does the action potential do?

A

Stimulates the release of calcium ions from the sarcoplasmic reticulum.
Calcium will then bind with troponin and cause the binding sites on the actin to be exposed.

24
Q

What is cross bridge formation?

A

The binding sites on the actin have been exposed (due to CA2+ binding to troponin)
The cross bridge is formed when the Myosin heads can attach to actin binding site.

25
Q

What is power stroke?

A

Pull of myosin head - moving (or sliding) the actin towards the m line which is the middle of the sarcomere.
Energy stored in the myosin head from ATP breakdown is used to perform the power stroke.

26
Q

What is cross bridge detachment?

A

Myosin head detaches from actin binding site.

ATP molecule binds to myosin head.

27
Q

What is cocking of the myosin head?

A

Myosin head cocks back into ready position.

ATP breaks down and forms ADP + P, the energy produced is stored in the myosin head for the power stroke.

28
Q

What is a motor neurone?

A

Carries action potential from brain to the muscle fibres to cause calcium to be released from sarcoplasmic reticulum

29
Q

What is the synaptic cleft?

A

Space between motor neurone and muscle

aka the Neuro-muscular junction

30
Q

What is the sarcoplasmic reticulum?

A

The structure which surrounds a muscle fibre. Calcium ions (CA2+) are stored here and when released, bind to the troponin on the actin filament starting the sliding filament mechanism.

31
Q

Which fibres are recruited first during exercise?

A

Slow twitch fibres recruited first. They will be replaced by fast twitch if activity is high intensity.

32
Q

What is the all or none law?

A

(When an action potential reaches the threshold)
‘All fibres within a unit will contract together and contract maximally’
If there is no action potential, the fibres within the unit will remain relaxed.

33
Q

What is a motor unit?

A

A motor neurone and the fibres it stimulates

Made up of all the same fibres (slow or fast twitch)

34
Q

What is spatial summation?

A

Recruitment of motor units to increase strength of contraction.
More units recruited
Larger fast twitch units recruited
Aka multiple unit summation

35
Q

What is wave summation?

A

Where a second stimulus is received shortly after the first, this doesn’t allow the fibre to fully relax and adds to the force of contraction making it stronger.

36
Q

What is tetanic contraction?

A

Aka tetanus
Where multiple stimuli are received in short succession allowing no time for the fibre to relax. A maximal and sustained contraction takes place.
Used in isometric contractions - handstands

37
Q

How can spatial summation be used to help delay fatigue?

A

The body rotates the units which are recruited allowing some units to recover before being used again.
Slow twitch units are recruited and rotated during low intensity exercise, like jogging.

38
Q

What is tonus?

A

Muscle tone! Muscles are partially contracted in order to increase speed of contraction

39
Q

What happens to the sarcomere when muscle fibres contract?

A

Z lines move closer together
A band stays the same
I band decreases
H zone decreases or disappears

40
Q

What are the two proprioceptors called which can be found in the muscles?

A

Muscle spindle apparatus

Golgi tendon organs

41
Q

What is the role of the proprioceptors?

A

To monitor the degree tension and stretch within a muscle and aim to prevent injury occurring through over stretching.

42
Q

What type of neurone are the proprioceptors attached to?

A

Sensory neurones. They are part of the nervous system and will send information from the muscles to the CNS (the brain) to stimulate a response.

43
Q

Can the proprioceptors cause muscular contraction?

A

No, not directly. They will send information as an action potential regarding the degree of stretch in the muscle to the CNS. The CNS will then send an action potential through the motor neurones to cause muscular contraction. (It is a relay system)

A Level PE Physiology (14 decks)

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