A twitch is defined as a single, brief contraction period and then relaxation period of a skeletal muscle in response to a single stimulation. Contraction period involves receptive power strokes that pull the thin filaments past the thick filaments shortening sacromeres and muscle tension increases as the sacromeres shorten. Relaxation period begins with or release of cross bridges resulting from the return of Ca2+ back to sarcoplasmic reticulum. The strength of skeletal muscle contractions can be broadly separated into twitch, summation, and tetanus. A twitch is a single contraction and relaxation cycle produced by an action potential within the muscle fiber itself.
Answer:
Macromolecule OR nucleic acid
Explanation:
It is one of four main types of macromolecules found in all forms of life, and its full name is deoxyribonucleic acid.
Best bet is macromolecule, but this is a very vague question so nucleic acid could also be correct.
Answer:
1.75 billion years
Explanation:
Scientists have concluded that Earth could potentially continue to host life for at LEAST another 1.75 billion years. As long as there's no natural disasters or nuclear wars, we should be good. (Right?)
But, eventually, over time Earth will become uninhabitable. :o
