Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber

A) lengthens.

B) shortens.

C) strengthens.

D) weakens.

E) pulls from the middle.

When sarcomeres shorten, the muscle fiber SHORTENS.

Explanation:

A muscle fiber is made up of many myofibrils that are attached at either end, which are composed of repeating subunits called sarcomeres that are responsible for muscle contraction. There are two types of filaments that makes up myofibrils they include;

- thick filaments and

- thin filaments

These filaments form the overlapping layers of sarcomeres. The contraction of muscle occurs through sliding- filaments model in the sarcomeres. The sarcomere and the muscle fibre shortens in length during muscle contraction ,due to the thick and thin filaments sliding over each other. I hope this helps, thanks.

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check this over.

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."