MUSCLE NERVE CARTILAGE BONE
SKELETAL MUSCLE
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
contraction
|
|
relaxation
|
|
Either A or B
|
|
None of the above
|
Detailed explanation-1: -According to the sliding filament theory, a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber. When all the sarcomeres in a muscle fiber shorten, the fiber contracts.
Detailed explanation-2: -For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments-the components of sarcomeres-do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.
Detailed explanation-3: -The molecular events of muscle fiber shortening occur within the fiber’s sarcomeres (see Figure 3). The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments.