Neuromuscular System Flashcards
Nervous system
Sympathetic + parasympathetic nervous systems are part of peripheral nervous system, role is to transmit info from brain to parts of body that need to adjust due to exercise
Types of muscle fibres
3 main types:
- slow oxidative (type one)
- fast oxidative glycolytic (type two a)
- fast glycolytic (type two x)
Characteristics of slow twitch fibre (type one)
Better adapted for lower intensity exercises such as long distance running
- slow contraction speed
-small motor neurone
- slow motor neurone conduction capacity
- low force produced
- low fatiguability
- high mitochondrial density
- high myoglobin content
- high capillary density
- very high aerobic capacity
- low anaerobic capacity
Characteristics of fast oxidative glycolytic fibres (type two a)
Used for events such as 1500m in athletics where a longer burst of energy needed
- fast contraction speed
- large motor neurone
- fast motor neurone conduction capacity
- high forced produced
- medium fatiguability
- medium mitochondrial density
- medium myoglobin content
- medium capillary density
- medium aerobic capacity
- high anaerobic capacity
Characteristics of fast glycolytic fibres (type two x)
Used for explosive events such as 100m in athletics where short, quick burst of energy are needed
- fast contraction speed
- large motor neurone
- fast motor neurone conduction capacity
- high forced produced
- high fatiguability
- low mitochondrial density
- low myoglobin content
- low capillary density
- low aerobic capacity
- very high anaerobic capacity
Motor unit
Consists of a motor neurone + a group of muscle fibres.
All or none law
Motor neurone stimulates muscle fibres
Either all contract or non contract. Not possible for them to partially contract.
A minimum amount of stimulation (threshold) required to start contraction.
If sequence of impulses equal or more than threshold, all muscle fibres in a motor unit will contract, however if less no contraction will occur
How to increase the strength of contraction
Wave summation
Tetanic contraction
Spatial summation
Wave summation
The breather the frequency of stimuli the greater the tension developed by the muscle. 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 powerful muscle contraction caused by a series of fast repeating stimuli.
Spatial summation
Occurs when impulses are received at the same time as different places on the neurone which add up to fire the neurone.
Uses bigger motor units + fast twitch fibres within muscle to development more force.
When the strength of a contraction changes by altering the number + size of the muscles motor unit
Proprioceptive neuromuscular facilitation (PNF)
It is an advanced stretching technique. Also considered to be the most effective forms of flexibility training to increase range of movement.
The technique for PNF is CRAC (contract-relax-antagonist-contract)
Muscle spindles role in PNF
Lie between skeletal muscle fibres
Often called stretch receptors as they provide info to the central nervous system (CNS) about how fast + far a muscle is being stretched. CNS sends impulse back to muscle telling it to contract which triggers stretch reflex
Stretch reflex cause muscle to contract to prevent over stretching, reducing injury
Golgi tendons role in PNF
found between muscle fibres + tendon
Detect levels of tension in muscle.
When muscle is contracted isometrically in PNF, they sense increase in muscle tension + send inhibitory signals to brain, allows antagonist muscle to relax+ lengthen. Known as AUTOGENIC INHIBITION
AUTOGENIC inhibition
Where there is a sudden relaxation of the muscle in response to high tension. The receptors involved in process are golgi tendons
