Describe the contraction of a single muscle cell and how does molecular chemistry ultimately get translated into movement?
Body movements depend greatly on the molecular interactions within the muscle cells. These interactions, while visual to you, start with chemical events within your cells.
The mechanism of alpha-adrenergic agonist-mediated force generation [is] in single hyperpermeable vascular smooth muscle cells. (PubMed, NIH)
Isotonic contraction shortens the muscle. Isometric contraction while the muscle is extended to full muscle length. Noncontractile portions, like tendons, must be pulled to a tightened position in order for isotonic muscle contraction to shorten; this is the series-elastic component.