1.3 Neuromuscular system
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What is the main role of the neuromuscular system?
Recruitment of different muscle fibre types, how they adjust the strength of contraction and PNF.
Describe the functions of the nervous system
The nervous system consists of two parts: The central and peripheral nervous system. The peripheral nervous system is made up of the sympathetic and parasympathetic nervous systems. They transmit information from the brain to the parts of the body that need to adjust in preparation for exercise.
What parts make up the nervous system?
CNS = Central nervous system = brain and spinal PNS = Peripheral nervous system = controls limbs
What systems makes up the peripheral nervous system and explain their roles
Sympathetic nervous system: prepares the body for exercise (‘fight or flight’) = decrease BP Parasympathetic nervous system: Relaxes the body slowing down any high energy functions = decrease BP
Describe the structure of the peripheral nervous system?
The peripheral nervous system consists of the nerves that branch out from the spinal cord.
Name the muscle fibre types
Slow oxidative (type 1) Fast oxidative glycolytic (type 2a) Fast glycolytic (type 2x)
Our bodies contain a mixture of all muscle fibre types just not in equal proportions. The mix of muscle fibres is mainly determined how?
Mix of muscle fibres are genetically determined
Describe the characteristics of a slow oxidative muscle fibre
• Slow contraction speed AND force • High fatigue resistance • Produce energy aerobically • Red in colour • High mitochondria density • High blood supply • Small size motor unit
Describe the characteristics of a fast oxidative glycolytic muscle fibre
• Dark pink • Medium blood supply • Medium mitochondria density • Medium recovery rate • Produce energy anaerobic • Fairly low fatigue resistance • Medium contraction speed/force
Describe the characteristics of a fast glycolytic muscle fibre
• White in colour • Fast contraction speed/force • Very low fatigue resistance • Large in size • Produce energy anaerobically • Low mitochondria content • Low blood supply
When describing the characteristics of a muscle fibre, what two groups can the characteristics be divided into? Give example for each
Structural = concerns the make up of the fibre Structural = myoglobin, mitochondrial, capillary density, size, colour Functional = what the fibre does Functional = fatiguability, force, contractile speed and force, aerobic/anaerobic
Name some functional characteristics of a slow oxidative muscle fibre
• Slow contraction speed • Small force • Aerobic capacity • High fatigue resistance
Name some structural characteristics of a fast glycolytic muscle fibre
• Large motor neurone size • Low mitochondria content • Low capillary density • Low myoglobin content
Describe a motor unit
A motor UNIT is a motor NEURONE and its muscle fibres.
Why is there a high mitochondrial density in Slow Oxidative fibres?
Mitochondria produces energy in the presence of oxygen therefor slow oxidative muscle fibres produce energy aerobically
What does a motor unit consist of?
A motor unit consists of a motor NEURONE and its muscle fibres
True of False: ALL the muscle fibres can be found in one particular motor unit
FALSE Only ONE type of muscle fibre can be found in ONE particular motor unit
Muscle fibres work with what system for a contraction to occur?
Muscle fibres work with the nervous system for a muscular contraction to occur
Explain how a muscle fibre’s contraction occur?
The motor neurone transmits a nerve impulse to the muscle fibre.
What does the motor neurone have at the end of its branches?
Each motor neurone has branches which end in the neuromuscular junction on the muscle fibre
Explain the all or none law
Once the motor neurone stimulates the muscle fibres, either all of them or non of them contract. IT IS NOT POSSIBLE FOR A MOTOR UNIT TO PARTIALLY CONTRACT.
What is required to start a muscular contraction in terms of the all or non law
If the sequence of impulses is equal to or more than the threshold, all the muscle fibres in a motor unit will contract. If the sequence of impulses is less than the threshold, no muscular action occurs.
List ways in which an athlete can increase the strength of contraction?
Wave summation Spatial summation
Explain ways in which an athlete can increase the strength of contraction?
Wave summation: repeated impulses with no time to relax to build a forceful, sustained, smooth contraction = tetanic contraction Spatial summation: when strength of contraction changes by altering the number and size of muscle’s motor units