Neuromuscular System Flashcards
(20 cards)
What part of the nervous system are the sympathetic and parasympathetic systems from?
Peripheral nervous system
What are the types of muscle fibres?
- slow oxidative (type I)
- fast oxidative glycolytic (type IIa)
- fast glycolytic (type IIx)
What are the characteristics of slow oxidative muscle fibres?
- slow contraction speed
- small motor neurone size
- low force produced
- low fatigability
- high myoglobin and mitochondria density
- high capillary density
- very high aerobic capacity
- low anaerobic capacity
- low PC stores
- low glycogen stores
What are the characteristics of fast oxidative glycolytic muscle fibres?
- fast contraction speed
- large motor neurone size
- high force produced
- medium fatigability
- medium myoglobin and mitochondria density
- medium capillary density
- medium aerobic capacity
- high anaerobic capacity
- high PC stores
- high glycogen stores
What are the characteristics of fast glycolytic muscle fibres?
- fast contraction speed
- large motor neurone size
- high force produced
- high fatigability
- low myoglobin and mitochondria density
- low capillary density
- low aerobic capacity
- very high anaerobic capacity
- high PC stores
- high glycogen stores
What is a motor unit?
Consists of a motor neurone and a group of muscle fibres
What does a motor neurone do?
Transmits nerve impulses from the central nervous system to the muscle fibres
What is the all-or-none law?
- once a motor neurone stimulates the muscle fibres all of them contract or none of them contract
- a minimum amount of stimulation (threshold) is required to start a contraction
What are the ways to increase the strength of contractions?
- wave summation
- spacial summation
What is wave summation?
- where repeated activation of the motor neurone stimulating the muscle fibres results in a greater force of contraction
- the greater the frequency of stimuli, the greater the tension developed by the muscle
What happens in the muscles during contraction?
- each time the muscle contracts calcium is released
- calcium needs to be present for a muscle to contract
- if there are repeated nerve impulses with no time to relax calcium will build up in the muscle cells
What is a tetanic contraction?
A forceful, smooth, sustained contraction which is caused by repeated nerve impulses, causing calcium to build up in the muscle cells
What is spacial summation?
- when the strength of a contraction changes by altering the number and size of the motor units
- when impulses are recieved at the same time at different places on a neurone which add up
- recruitment of bigger motor units
- activation of motor units is staggered to delay fatigue
What does PNF stretching stand for and what is it?
- Proprioceptive Neuromuscular Facilitation
- an advanced stretching technique for flexibility training
What are muscle spindles and how do they work?
- proprioceptors that detect how far and how fast a muscle is being stretched and produce the stretch reflex
- found between muscle fibres
- send signals to the CNS
- CNS sends impulse back to the muscle to contract (stretch reflex)
- prevents overstretching and risk of injury
What are Golgi tendon organs and how do they work?
- structures that detect levels of tension in a muscle
- found between muscle fibres and tendons
- they sense increases in muscle tension when a muscle is being stretched
- send inhibitory signals to the brain to override the stretch reflex
- antagonistic muscle relaxes and lengthens
- this is known as autogenic inhibition
What is autogenic inhibition?
A sudden relaxation of the muscle in response to high tension
What is the most practical PNF stretching method and what is the process
- CRAC - contract - relax - antagonist - contract
- passive partner stretch 1, held for 10-12 seconds
- isometric contraction
- passive stretch 2, through greater range of movement
- repeat
What is muscular hypertrophy?
Increase in the size of myofibrils per fibreor muscle (increase in muscle size)
What is muscular hyperplasia?
Increase in the number of myofibrils per fibre (increase in number of mucles fibres)
