Transcript Question 1 - dimacleans

Question 1
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Muscle
Fibre
Myofibril
Sarcomere
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Myosin
(thick filament)
Actin
(thin filament)
Question 2
Skeletal muscles exist in opposing pairs, to enable movement.
In the arm, bending of the elbow requires:
 Contraction of biceps and relaxation of triceps muscles.
 Biceps muscle is attached to the forearm bone (radius) via a tendon.
 Shortening of the biceps muscle pulls the radius towards the upper arm bone
(humerus), causing it to bend at the elbow joint.
In the arm, straightening of the arm requires:
 Contraction of triceps and relaxation of biceps muscles
 Triceps muscle is attached to the forearm bone (ulna) via a tendon.
 Shortening of the triceps muscle pulls the ulna away from the humerus,
causing it to straighten at the elbow joint.
Question 3
When there is a lack of O2, muscles cramp, meaning
muscle fibres remain contracted and shortened.
[Achieved]
Mechanism of muscle contraction: [Merit]
In the presence of ATP, myosin heads attach to actin.
Myosin pulls actin filaments towards each other,
shortening the sarcomeres.
Shortening of sarcomeres = shortening of muscle fibres =
shortening of whole muscles.
Question 3 [Excellence]
Stretching can relieve muscle cramping by:
Pulling the actin and myosin fibres apart, returning them
towards their resting state.
Increasing blood flow to cramped muscles.
Blood carries both O2 and glucose, which are needed for
respiration to make ATP.
ATP is needed for myosin heads to detach from actin, so
increased ATP will aid muscle relaxation, which will relieve
cramping.
ATP is also involved in cellular repair and recovery.