Topic 4
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Label a diagram of a motor unit
Limit to: 7 marks * dendrite * cell body * nucleus * axon * motor end plate * synapse * muscle
Explain the role of neurotransmitters in stimulating skeletal muscle contraction
Limit to acetylcholine and cholinesterase. When a nerve action potential arrives at a motor end plate, Acetylcholine (Ach) is released from the synaptic knobs and diffuses across the synaptic cleft to bind with post-synaptic receptors. This takes approximately 0.5 milliseconds to complete and is followed by a muscle action potential which is required to initiate muscular contraction. Once the nerve action potential is completed, Cholinesterase is released. This enzyme is responsible for the hydrolysis of acetylcholine into choline and acetic acid, clearing the synaptic cleft in readiness for the next impulse. This is necessary in order to avoid continuous synaptic transmission.
Explain how skeletal muscle contracts by the sliding filament theory
Include the terms: * myofibril * myofilament * sarcomere * actin * myosin * H zone * A band * Z line * tropomyosin * troponin * sarcoplasmic reticulum * calcium ions * ATP. Aim 7: Various online muscle contraction simulations are available
Explain how slow and fast twitch fibre types differ in structure and function
Limit fibre types to slow twitch (type I) and fast twitch (type IIa and type IIb). Type IIa and IIb are high in glycogen content depending on training status. Aim 8: Implications of invasive techniques for taking samples, such as muscle biopsies. Aim 9: Implications of drawing conclusions from indirect measurements.
Outline the types of movement of synovial joints
Outline the types of muscle contraction
Isotonic: Muscle changes length under constant tension (e.g., bicep curl). Isometric: Muscle contracts without changing length (e.g., plank). Isokinetic: Muscle moves at a constant speed with variable resistance (e.g., rehab machines). Concentric: Muscle shortens while contracting (e.g., lifting a weight). Eccentric: Muscle lengthens while contracting (e.g., lowering a weight).
Explain the concept of reciprocal inhibition
Analyse movements in relation to joint action and muscle contraction
Explain delayed onset muscle soreness (DOMS) in relation to eccentric and concentric muscle contractions
Define the terms force, speed, velocity, displacement, acceleration, momentum and impulse
Scalar - a measurement that only has size (ex. 5m) Vector - a measurement that has both size and direction (ex. 5m west) Force - the mechanical interaction that goes on between 2 objects Speed - the rate at which someone or something is able to move or operate Velocity - the speed of something in a given direction Displacement - how far an object has moved horizontally, vertically or laterally Acceleration - the increase in rate of speed • Momentum -the measure of the amount of motion possessed by a moving bodyrelated to 3rd lawP = mv • Conservationtotal momentum of two objects before impact will equal the total momentum after impact. Impulse - force x time, during impulse you create more velocity Term | Equation | Unit | | — | — | — | | Force | mass x acceleration | N | | Speed | distance/time | m/s | | Velocity | displacement change/time | m/s | | Acceleration | change in velocity/time | m/s² | | Momentum | mass of object x velocity | kgm/s | | Impulse | force x time | N/s |
Analyse velocity–time, distance–time and force– time graphs of sporting actions
Define the term centre of mass
Explain that a change in body position during sporting activities can change the position of the centre of mass
Distinguish between first, second and third class levers
Label anatomical representations of levers
Define Newton’s three laws of motion.
Explain how Newton’s three laws of motion apply to sporting activities
State the relationship between angular momentum, moment of inertia and angular velocity
Explain the concept of angular momentum in relation to sporting activities
Explain the factors that affect projectile motion at take-off or release
Outline the Bernoulli principle with respect to projectile motion in sporting activities