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Physical Education > AOS 1: muscular system > Flashcards

AOS 1: muscular system Flashcards

1
Q

The muscular system

A
  • Production of movement
  • Stabilisation of posture
  • Essential body functions
  • Thermogenesis (heat generation)

Can be performed on demand (voluntarily) or automatically (involuntarily)

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2
Q

Types of muscles

A
  • Skeletal
  • Cardiac
  • Smooth
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3
Q

Cardiac muscle

A

Found only in the heart
- Involuntarily controlled
- Not easily fatigued

Has a striped appearance

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4
Q

Smooth muscle

A

Found in hollow organs
e.g. walls of digestive tract

No conscious control over smooth muscle contractions
- Fatigues much slower than skeletal muscle

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5
Q

Skeletal muscles

A

Attaches to and causes movement of the skeleton
- Under voluntary control

Has a striped appearance (striated)

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6
Q

Skeletal muscle structure

A

Muscles are attached to bones via tendons situated at the ends of the muscle belly.

The points of attachment are known as the origin and insertion points

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7
Q

The Origin

A

The attachment site that doesn’t move during contraction and is usually proximal to the body

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8
Q

The insertion

A

The attachment site that does move and is usually distal to the body

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9
Q

Major muscles

A

Deltoid, Pectoralis major, biceps brachii, serratus anterior, rectus abdominus, obliques, quadriceps, soleus, tibialis anterior, trapezius, tricpes brachii, latiussumus dorsi, erector spinae, gluteus maximus, hamstring, gastrocnemius

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10
Q

Muscle fibre arrangement

A
  • Circular
  • Convergent
  • Parallel
  • Pennate
  • Fusiform
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11
Q

Convergent muscles

A

Has a broad origin, and its fascicles converge towards a single tendon of insertion

Convergent muscles are triangular or fan shaped

e.g. pectoralis major

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12
Q

Parallel muscles

A

The length of the fascicles run parallel to the long axis of the muscle

Parallel muscles are “strap-like”

e.g. femur tendon

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13
Q

Pennate muscles

A

Muscle fibres are short and attach obliquely to a central tendon that runs the length of the muscle. They comes in three forms:
- Unipennate
- Bipennate
- Multipennate

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14
Q

What does pennation allow?

A

Pennation allows more fibres to be packed into a muscle, increasing the force it can produce.

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15
Q

Unipennate muscles

A

Unipennate Muscles: Muscle fibres branch out from one side of the tendon

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16
Q

Bipennate muscles

A

Bipennate muscles: Muscle fibres branch out from both sides of the tendon

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17
Q

Multipennate muscles

A

Involve multiple rows of muscle fibres whose central tendon branches into two or more tendons

e.g. deltoid

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18
Q

Benefits of multipennate muscles

A

Multipennate muscles provide the greatest force due to:
- Short fibres
- More fibres packed into muscle
- Large cross-sectional area

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19
Q

Fusiform muscles

A

Are spindle shaped with a belly that is wider than the origin and insertion

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20
Q

Function of fusiform?

A

Fusiform muscles generate lower force but enable greater velocities due to:
Long fibres
Fibres running in the same direction as the tendon

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21
Q

Muscular contractions

A

Skeletal muscles create movement by pulling on the bones to which they attach

There are three types of muscular contractions classified according to the movement they cause:
- Isoinertial (concentric and eccentric)
- Isometric
- Isokinetic

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22
Q

Isoinertial contractions

A

Muscle length changes through a range of motion or action

Two types of isotonic contractions:
- Concentric contractions
- Eccentric contractions

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23
Q

Concentric contractions

A

Concentric contractions are characterised by the shortening of the muscle and a reduced joint angle

24
Q

Eccentric contractions

A

Eccentric contractions are characterised by the lengthening of the muscle and an increased joint angle

25
Q

Isometric contractions

A

Muscle does not or cannot change length while producing force and there is no movement of the joint to which the muscle is attached

Isometric contractions result in the greatest muscle tension and have the largest force-producing capacity

26
Q

Isokinetic contractions

A

Muscle works at a constant angular velocity through the full range of motion
- Only performed using special equipment

Effective way to develop strength and endurance

27
Q

Reciprocal inhibition

A

Skeletal muscles work in pairs to create movement
- One muscle will contract (shorten) while the other relaxes (lengthen)
- Other muscles work to stabilise the moving joint

28
Q

Agonist

A

The muscle directly involved with initiating and performing a movement

29
Q

Antagonist

A

The muscles that oppose this movement

30
Q

Stabilisers

A

The muscles that ensure the joint remains stable while the agonist and antagonist are working

31
Q

Example of reciprocal inhibition

A

Bicep contracted (agonist), triceps relaxed/extended (antagonist) vice versa.

32
Q

Muscle pairs

A

Hamstrings - quadriceps, gluteus maximus - hip flexor, gastrocnemius - tibialis anterior, pectoralis major - latissimus dorsi

33
Q

Skeletal Muscle Control-
Initiation of Activity

A

Step 1: A signal must be sent from the brain to the muscle
Step 2: The message travels down the spinal cord to the motor nerves that branch out to the relevant muscles (motor nerve separates into smaller motor neurons to attach to individual muscles)

34
Q

Initiation of activity

A

Step 3: Nerve impulse travels across the neuromuscular junction with the assistance of a neurotransmitter (acetylcholine)
Step 4: The muscle will continue to contract for as long as the brain sends messages

35
Q

The motor unit

A

Consists of a motor neuron and all the muscle fibres it innervates
- Responsible for activating a particular type and number of muscle fibres, resulting in muscle activity

All muscle fibres of a motor unit contract and relax together

36
Q

Number of fibres in motor unit

A

The number of fibres within each motor unit varies according to the precision of the movement required

Muscles that perform precise movements generally have small motor units, while muscles that perform gross motor skills generally have large motor units

37
Q

The Neuromuscular Junction

A

Small space between the end of a neuron and the adjacent muscle cell
- Nerve impulse must travel across the neuromuscular junction to stimulate the muscle fibres

38
Q

Neurotransmitter

A

Acetylcholine (a neurotransmitter) helps the nerve impulse travel across the synaptic cleft to the adjacent muscle fibres

39
Q

Muscle Fibre Recruitment-
The Size Principle

A
  • The recruitment of motor units within a skeletal muscle commences with smaller motor units to large motor units
  • Smaller motor units are recruited first at low muscle forces
  • An increase in muscle force leads to an increase of larger motor units
40
Q

The Size Principle - small motor units

A
  • Slow contracting
  • Easily excitable and recruited
  • Fatigue resistant
  • Utilised for prolonged activities (walking, posture control)
41
Q

The size principle - Large motor units

A
  • Fast contracting
  • Less easily excitable and recruited
  • Rapidly fatiguable
  • Utilised for high force activities (sprinting, hitting, jumping)
42
Q

“All or Nothing” Principle

A

A nerve impulse will not stimulate the muscle fibres until it reaches a certain threshold level

When the threshold is reached, all fibres of the motor unit will contract at the same time and maximally

If the impulse is too weak, no fibres will contract at all.

43
Q

Aerobic

A

energy production using oxygen

44
Q

Anaerobic

A

energy production without oxygen

45
Q

Red blood cells

A

transport oxygen in the blood

46
Q

Capillaries

A

smallest blood vessels which exchange oxygen between the blood and muscles or different tissues of the body

47
Q

Mitochondria

A

produce energy in our muscles using oxygen

48
Q

Myoglobin

A

transports oxygen from the blood into the mitochondria

49
Q

Muscle Fibre Types

A

Two basic types of muscle fibres classified based on their structure and function
- Type I / Slow twitch / Red fibres
- Type II / Fast twitch / White fibres

Each fibre type is better suited to a different intensity of physical activity

50
Q

Type I Fibres

A

Best suited to aerobic, endurance work

Type I fibres:
- Contract slowly and repeatedly over a period of time
- Produce low force
- Are highly resistance to fatigue
- Contain large amounts of myoglobin, mitochondria and capillaries
- Have a high capacity to generate ATP by oxidative metabolic processes

51
Q

Type II Fibres

A

Best suited to short duration, high intensity anaerobic work

Type II fibres:
- Contract rapidly for a short period of time only
- Fatigue quickly
- Develop a high level of force
- Have a high capacity to generate ATP by anaerobic metabolic processes

52
Q

Type II A / Fast twitch oxidative

A

Type II A fibres are partially aerobic
- Fatigue resistance: medium/low
- Force capacity: Intermediate
- Contraction speed: moderate

53
Q

Type II B / Fast twitch glycolytic

A

Type II B fibres are purely anaerobic.
- Fatigue resistance: low
- Force capacity: High
- Contraction speed: high

54
Q

explanation of “all or nothing” principle

A

In order to initiate …, a nerve impulse must be sent from the brain to the required muscles via the spinal cord. The … principle states that this signal must be strong enough to reach a threshold level in order to stimulate the muscle fibres. If this threshold is not reached, no muscle fibres will contract.

During the match, the signal reaching the motor units of the (arm) were strong enough to cause the muscles to contract, (allowing elbow extension to start the serving action.)

55
Q
A

Physical Education (5 decks)

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