<span>Muscle cells are uniquely adapted to contractile function due to three main things. FIrst, they have a large capacity for storage of readily available glycogen to use for work. Second, they contain the actin and myosin cross-bridge cycling structure to perform a contraction of a muscle fiber. Finally, each fiber has central nervous innervation to control contraction and relaxation of the muscle fibers.</span>
Because since their ancestors came before them then they inherit certain beneficial traits that help them survive. Those traits are in the DNA and the animals are evolving to be more fit for the environment that they are in. (hope this helps)
If you eat unhealthy now then you could develop health issues such as diabetes heart problems wating disorders and cause obesity if you eat unhealthy then you probably won't live as long of a life as compared to someone who has been eating healthy and the if you eat good now you can love a longer life with less problems
Ball and Socket Joint
This type of joint allows for a wide range of rotation and movement. The shoulder and hip are ball and socket joints.
Explanation:
guessing
amino acid?
protein building blocks
peptide bonds hold them together