Answer:
Why are muscle and fat levels the only factors influencing flexibility impacted by personal decisions? Age, gender, and joint structure cannot be changed. ... Muscle stiffness that reduces flexibility often results from the overuse of muscle, but inactivity also weakens muscles and can make them more susceptible to injury.
Answer:
I'm not sure so sorry maybe someone will know
Answer:
b. The rats press the lever least when cocaine is presented.
Explanation:
Reinforcement or reward refers to the physiological processes by which a given behavior, such as drug use, becomes habitual. This occurs when neurons release the neurotransmitter dopamine to the nucleus accumbens (NAc) after drug use.
In tobacco, nicotine is the main component triggering of the reinforcement. Once inside the brain, nicotine activates nicotinic receptors, which in turn contributes to the reinforcement mechanism. Following repeated exposure to nicotine, a neuroadaptation process is established for some (but not all) effects of nicotine. Increased brain nAChRs (acetylcoline receptors) are observed in response to desensitization of these nicotine-mediated receptors. This desensitization can play an important role in the development of tolerance and dependence.
The fact that nicotine is a weak reinforcer, means that maybe the rat already had an neuroadaptation with this drug, not feeling anything with this drug anymore, and thats why he would prefer other drug, like cocaine, pressing the lever of nicotine less often.
