A testable question is something you need data for, ex: if i bounce a bouncy ball from larger heights, how high will it fly? it can't be just a regular yes or no question
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Answer:
Dopamine.
Explanation:
Cocaine is used as a recreational drug and addictive in nature. It can be smelled or directly inhaled in the veins. This drug causes the feeling of restless and happiness.
The dopamine is the important neurotransmitters that regulates the mood and other biological activity of the body. The cocaine inhibit the reuptake of dopamine and leads to its accumulation in the brain. This might also break the blood brain barrier.
Thus, the answer is dopamine.
Each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber Shortens
Mechanism :
Myofibrils are components of the animal skeletal muscles that are made up of sacromeres. They perform the muscular contraction and relaxation via the sliding filament model.
To produce motion, A cross-bridge forms between actin and the myosin heads triggering shortening of the sacromere. This shortening of the sacromere results in the contraction of the muscle fibers, which the net effect can be seen to be a shortening of the fibers.
To learn more about myofibril refer to : brainly.com/question/15461128
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