The contraction of cardiac muscles is caused by:
Correct answer: A. Spontaneous stimuli
- A. Spontaneous stimuli
- B. Nervous stimuli
- C. Stretch stimuli
- D. Hormonal stimuli
Explanation
Cardiac muscles are myogenic and the stimulus is generated by the SA node spontaneously. Each cardiac muscle cell fires an action potential as a result of excitation propagated from the sinoatrial node, which produces muscle cell contraction. A wave of action potentials spreads across the organ to produce a coordinated contraction of the heart and efficient ejection of blood to the body.
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About Support and Movement
Support and movement covers the axial and appendicular skeleton, bone structure, joints and the arrangement of skeletal muscles. Muscle contraction is explained through actin, myosin, sliding filaments, calcium ions and ATP, while arthritis is distinguished as a disorder of joints rather than a normal part of movement.
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