5. Muscular System Flashcards
List the 3 types of Muscle Fibre Arrangements
Fusiform, Pennate and Radiate.
Outline Fusiform
Fusiform muscles are long and thin. Fibres run the length of the muscle belly. Designed for mobility. Produce low force. Eg Biceps
Outline Radiate
Radiate from the main tendon. Compromise b/w fusiform and pennate. Capable of strength and power whilst retaining mobility
Outline Pennate
Run at angles to the tendons. Limited Mobility. Designed for Strength and power
List the 3 types of Pennate muscle fibre arrangements
Unipennate, Bipennate and multipennate
Outline Unipennate
Fibres on one side of the central tendon. Eg Semimembranosus tibialis anterior
Outline Bipennate
Fibres run off either side of central tendon. E.g. Rectus femoris
Outline Multipennate
Fibres branch out from several tendons. This arrangement allows for the most force. E.g. deltoid.
Describe Slow Twitch muscle fibres
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
Describe Type 2a muscle fibres
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
Describe Type 2b muscle fibres
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)
Outline Reciprocal Inhibition
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
Outline the Agonist
This muscle causes the major action. Eg During the bicep curl up phase the bicep is agonist
Outline the Antagonist
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
Outline Stabilisers
- 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.
List the 4 types of contractions
Isotonic concentric, Isotonic eccentric, Isometric, Isokinetic
Outline Isotonic eccentric contractions
Muscle lengthens while the force is developed
Outline isometric contractions
Force is developed but there is no change in the length of the muscle.
Outline Isotonic concentric contractions
Muscle length shortens during contraction
Outline Isokinetic concentric contractions
Force created by the muscle is maximal through the whole range of motion.
List the 7 components of a Sarcomere
Myosin, Myosin Cross Bridges, Actin, A Band, H Zone, Z Line, I Band
Outline the changes that occur when the Sarcomere contracts
H Zone shortens and disappears, I Band shortens
Describe the sliding filament theory
- 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
Outline what a motor unit consists of.
A motor unit consists of a motor neuron and the muscle fibres it stimulates.
Describe the all or nothing principle
- 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.
How can you vary the amount of force in an effort?
By varying the number of motor units recruited.
