Neuromuscular System Flashcards
What are the structural characteristics of a slow twitch muscle fibre?
- High levels of myoglobin
- Lots of mitchondria
- High levels of triglyceride
- High capillary density
- High levels of oxidative enzymes
What is the significance of high levels of triglyceride and oxidative enzymes?
Triglyceride - more fats for energy
Oxidative enzymes - more enzymes to break down energy sources such as glucose and fats
What is the significance of a larger/faster motor neurone and larger diameter of fibre?
Larger diameter of fibre - more explosive strength/force for activity
Faster motor neurone - faster speed for activity
What is the role of the golgi tendon organ?
- Detects increased tension from isometric contraction and causes the muscle to relax
- This is known as autogenic inhibition
- Then override the stretch reflex which allows a greater range of movement
How are muscle fibres recruited?
- Nerve impulse travels from the brain, along the spinal cord to a motor neuron
- This triggers the muscle fibres attached to the end of it to contract
- Group of muscle fibres is a motor unit
- Which is the minimum unit of contraction
What is meant by the ‘All or None Law’
If a motor unit receives sufficient stimulation an action potential will be released, and all the fibres in the motor unit will contract
How do spindle fibres help vary the strength of contraction?
- Detect change in muscle length
- If stretching occurs, the muscle contracts with more force to prevent overstretching by initiating the stretch reflex (a powerful contraction)
Explain wave summation
- Increase in frequency of impulse produces a stronger contraction
- Motor unit unable to relax so the force increases
Explain tetanic contraction
- A sustained muscular contraction
- Caused by a series of nerve stimuli repeated so rapidly that individual muscular responses are fused
- Produces a sustained, powerful tetanic contraction
