Neuromusuclar System

Question 1

what is the neuromuscular system?

Answer 1

how the nervous system (brain, spinal cord, and nerves) and muscular system (muscles) work together to control movement

Question 2

what does the neuromuscular system do? (2)

Answer 2

• when you want to move, the brain sends a signal down the spinal cord to motor neurons, which then activate motor units in the muscle
• this impulse is sent via the cerebrum

Question 3

what is the role of acetylcholine in the neuromuscular system? (2)

Answer 3

• when the brain sends a signal through the nerves to the muscle, acetylcholine is released at the end of the nerve, crossing the synapse
• when it reaches the muscle, it binds to receptors, causing the muscle fibres to contract and create movement

Question 4

list the functional characteristics of TYPE I muscle fibres (4)

Answer 4

• slow speed of contraction
• very high fatigue resistance
• primarily an aerobic energy source
• low force production

Question 5

list the structural characteristics of TYPE I muscle fibres (5)

Answer 5

• high mitochondrial density
• high capillary density
• high myoglobin content
• small fibres
• small motor units

Question 6

list the functional characteristics of TYPE II muscle fibres (4)

Answer 6

• fast speed of contraction
• moderate fatigue resistance
• primarily aerobic energy source but can use anaerobic pathways
• moderate force production

Question 7

list the structural characteristics of TYPE II muscle fibres (5)

Answer 7

• moderate mitochondrial density
• moderate capillary density
• moderate myoglobin content
• medium sized fibres
• medium sized motor units

Question 8

list the functional characteristics of TYPE II B/X muscle fibres (4)

Answer 8

• very fast speed of contraction
• low fatigue resistance
• primarily anaerobic energy source
• high force of production

Question 9

list the structural characteristics of TYPE II B/X muscle fibres (5)

Answer 9

• low mitochondrial density
• low capillary density
• low myoglobin content
• large fibres
• large motor units

Question 10

ALL-OR-NONE LAW (2)

Answer 10

• refers to how a muscle will contract or not at all
• the action potential must be met or surpassed for contractions to occur

Question 11

short-term responses of the neuromuscular system (6)

Answer 11

increase in nerve transmissions
immediate increase in neural impulses (action potential) to the muscles

immediate muscle activation
increase in nerve impulses means rapid recruitment of motor units, enhancing muscle contraction

motor unit recruitment

muscle fibre type recruitment

reflex responses
reflex arcs respond rapidly to changes in muscle length and tension, helping to maintain posture and joint stability

blood flow regulation
blood flow to the active muscles increases rapidly

Question 12

long-term responses of the neuromuscular system (6)

Answer 12

increased motor unit recruitment

enhanced muscle activation
strength and endurance training lead to increased muscle activation levels

muscle fibre type adaptations

increased motor unit synchronisation and improved motor neuron firing rates
improved nerve to muscle connections contribute to increased force production

summation of motor units
the ability to fire a lot of impulses in target muscles all at once is improved with strength and power training

muscle hypertrophy

Question 13

EXAM STYLE Q:
‘justify why type I fibres are predominantly used by long-distance runners?’

Answer 13

structural (2 marks)
functional (2 marks)