1.3 The Neuromuscular System Flashcards
What does the autonomic nervous system regulate ?
The function of our internal organs such as the heart and also controls some of our skeletal muscles with in the body
How does the autonomic nervous system work ?
Involuntary, things take place which we do not notice
What is the movement of muscles during exercise controlled by ?
Brain via nerves
Neuromuscular system
where the nervous system and the muscles work together to allow movement
Three main types of muscle fibre
Slow oxidative (type I)
Fast oxidative glycolytic (type IIa
Fast glycolytic (type IIb)
Aerobic
literally means ‘with oxygen’ so it refers to exercise that is low to medium intensity where the oxygen demand of the muscles can be met
Anaerobic
Means ‘without oxygen’ and refers to exercise at high intensity such as sprinting, where the demand for oxygen by the muscles is so high that it cannot be met.
Slow twitch fibres (type 1)
These fibres have a slower contraction speed than fast twitch fibres and are better adapted to lower intensity exercise such as long-distance running. They produce most of their energy aerobically (using oxygen)
Fast twitch fibres (Type II)
These fibres have a much faster contraction speed and can generate a greater force of contraction. However, they also fatigue very quickly and are used for short, intense bursts of effort. They produce most of their energy anaerobically (without oxygen).
Two types of fast twitch fibre and their characteristics
- Type Ila fast oxidative glycolytic - these fibres are more resistant to fatigue and are used for events such as the 1500m in athletics where a longer burst of energy is needed.
• Type Ilb fast glycolytic - these fibres fatigue much quicker than type lla and are used for highly explosive events such as the 100m in athletics where a quick, short burst of energy is needed.
Characteristics of Slow twitch muscle fibres (Type I)
Small motor neurone size
High mitochondrial density
High capillary density
Slow contraction speed (110)
Characteristics of Fast twitch type IIa muscle fibres
Large motor neurone size
Medium mitochondrial density
Medium capillary density
Fast contraction speed (50)
Characteristics of Fast twitch type IIb muscle fibres
Large motor neurone size
Low mitochondrial density
Low capillary density
Fast contraction speed (50)
Hypertrophy
Where the muscle has become bigger and stronger. (Through training)
Motor unit
A motor neurone and its muscle fibres.
Motor neurones
Nerve cells which transmit the brains instructions as electrical impulses to the muscles
Neuromuscular junction
Where the motor neurone and muscle fibre meet
What is each muscle made up of
Many motor units and they vary in size . A small muscle will have motor units that only have a few fibres per motor neurone . However a large muscle will have motor units with a motor neurone feeding hundreds of fibres
All or none law
Where a sequence of impulses has to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract. If not, none of them contract.
For low intensity activity what motor units will the brain recruit
Slow twitch motor units
(Jogging , long-distance swimming)
For high intensity activity what motor units will the brain recruit
Fast twitch motor units
(Sprinting , power lifting )
How to increase the strength of contraction
Wave summation
Tetanic summation
Spatial summation
Wave summation
Where there is a
repeated nerve impulse with no time to
relax so a smooth, sustained contraction
occurs, rather than twitches.
Tetanic contraction
A sustained muscle contraction caused by a series of fast repeating stimuli
Spatial summation
When the strength of a contraction changes by altering the number and size of the muscles motor units
What needs to be present for a muscle to contract
Calcium
What is PNF (Proprioceptorive neuromuscular facilitation) ?
an advanced stretching technique for increasing range of motion . There are a few different PNF techniques but the most practical is the CRAC technique (contract-relax-antagonist-contract)
What is involved in PNF
Two Proprioceptors:
muscle spindles
Golgi tendon organs
Muscle spindles
These detect how far and how fast a muscle is being stretched and produce the stretch reflex
Golgi tendon organs
These are activated when there is tension in a muscle
Isometric contraction
Where there is tension in a muscle but no visible movement
Autogenic inhibition
Where there is a sudden relaxation of the muscle in response to high tension. The receptors involved in this process are Golgi tendon organs
