<em>Muscle cells are excitable, meaning they react to stimuli. They may shorten and create a pulling force because they are contractile. Locomotion, facial expressions, posture, and other voluntary motions of the body are all made possible by the contraction of skeletal muscle, which is connected to bones.</em>
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<em>Also, Taylor Swift*</em>
In a solar system, there is a sun that is in the middle and has planets orbiting around it. The same way, the nucleus is in the middle with electrons orbiting the nucleus. <span />
Answer:
1.) Why does menstruation begin?
A.) Period happens because of changes in hormones in the body.
2.) How long does the menstrual cycle usually last?
A.) the menstrual cycle lasts 21 to 35 days while bleeding between 2 to 7 days
<u>-TheUnknownScientist</u>
I hope this help, answer is 125.5kcal♀️
