5. Muscular System

Question 1

List the 3 types of Muscle Fibre Arrangements

Answer 1

Fusiform, Pennate and Radiate.

Question 2

Outline Fusiform

Answer 2

Fusiform muscles are long and thin. Fibres run the length of the muscle belly. Designed for mobility. Produce low force. Eg Biceps

Question 3

Outline Radiate

Answer 3

Radiate from the main tendon. Compromise b/w fusiform and pennate. Capable of strength and power whilst retaining mobility

Question 4

Outline Pennate

Answer 4

Run at angles to the tendons. Limited Mobility. Designed for Strength and power

Question 5

List the 3 types of Pennate muscle fibre arrangements

Answer 5

Unipennate, Bipennate and multipennate

Question 6

Outline Unipennate

Answer 6

Fibres on one side of the central tendon. Eg Semimembranosus tibialis anterior

Question 7

Outline Bipennate

Answer 7

Fibres run off either side of central tendon. E.g. Rectus femoris

Question 8

Outline Multipennate

Answer 8

Fibres branch out from several tendons. This arrangement allows for the most force. E.g. deltoid.

Question 9

Describe Slow Twitch muscle fibres

Answer 9

Type 1, slower and less powerful contractions, resistant to fatigue, high capcity to use oxygen. Suited to low intensity, longer duration aerobic work. Eg Marathons. Red in color

Question 10

Describe Type 2a muscle fibres

Answer 10

High capacity to use oxygen to generate energy, split ATP at a very rapid rate therefore has fast contraction speed and are resistant to fatigue, best suited to middle distance running. Pink in color

Question 11

Describe Type 2b muscle fibres

Answer 11

Create energy without using oxygen (anaerobic), fatigue easily. Fatigue easily, split ATP at a fast rate, have a very fast contraction speed that is powerful. Suited to high intensity, short duration, anaerobic work, such as sprinting and field events in athletics.White in color (Think lightning)

Question 12

Outline Reciprocal Inhibition

Answer 12

Muscle work in pairs or groups to produce movement. One muscle contracts whilst the other muscle relaxes. Eg. Quadriceps contract to kick a football while the hamstrings relax

Question 13

Outline the Agonist

Answer 13

This muscle causes the major action. Eg During the bicep curl up phase the bicep is agonist

Question 14

Outline the Antagonist

Answer 14

This muscle will relax and lengthen to allow a movement to occur. Eg In a bicep curl up phase the bicep is agonist and tricep is antagonist

Question 15

Outline Stabilisers

Answer 15

• These muscles ensure the joint remains stable while the agonist and antagonists are working.
• Eg when kicking a football the erector spinae and rectus abdominis will contract to stabilise the body.

Question 16

List the 4 types of contractions

Answer 16

Isotonic concentric, Isotonic eccentric, Isometric, Isokinetic

Question 17

Outline Isotonic eccentric contractions

Answer 17

Muscle lengthens while the force is developed

Question 18

Outline isometric contractions

Answer 18

Force is developed but there is no change in the length of the muscle.

Question 19

Outline Isotonic concentric contractions

Answer 19

Muscle length shortens during contraction

Question 20

Outline Isokinetic concentric contractions

Answer 20

Force created by the muscle is maximal through the whole range of motion.

Question 21

List the 7 components of a Sarcomere

Answer 21

Myosin, Myosin Cross Bridges, Actin, A Band, H Zone, Z Line, I Band

Question 22

Outline the changes that occur when the Sarcomere contracts

Answer 22

H Zone shortens and disappears, I Band shortens

Question 23

Describe the sliding filament theory

Answer 23

• Myosin cross bridges attach to the actin filaments.
• They then pull them into the centre of the sarcomere in a rowing action.
• This causes the H Zone to shorten and then disappear

Question 24

Outline what a motor unit consists of.

Answer 24

A motor unit consists of a motor neuron and the muscle fibres it stimulates.

Question 25

Describe the all or nothing principle

Answer 25

• Muscle fibres can not vary the amount of force they produce.
• They simply contract fully or not at all. A single muscle contraction is initiated by an electrical signal from the brain to a motor unit.
• When the stimulus strength reaches a certain threshold the muscle will contract fully.
• If the stimulus strength threshold is not met, the muscle will not contract at all.

Question 26

How can you vary the amount of force in an effort?

Answer 26

By varying the number of motor units recruited.