This book describes muscle contraction and the structure and physiology that make muscle contraction possible. The following sections will cover the three major muscle types (skeletal (striated), smooth, and cardiac), explaining how each contracts, what controls the onset and end of a contraction, and what controls the strength of a contraction. The chapters will look at the physical, chemical, and electrical interactions that take place in muscle contraction.
This book is ideal for high school students taking honors biology, entry level college students (including both biology major and non-major students), and those in entry level physiology course. Entry level physiology courses can include those in medical, dental, nursing, and other professional schools.
Muscle contraction is at the heart of life, literally, for most organisms on the planet. For humans, the force that pumps blood throughout our bodies is generated by the contraction of cardiac muscle and the regulation of the vessels through which that blood flows is similarly controlled by smooth muscle. The third type of muscle, skeletal or striated, is what makes it possible for us to run, jump and type on a keyboard. Muscles are essential to everything we do.
Each muscle in the human body is a marvel of molecular engineering and functions as the result of a remarkable machine called a sarcomere. These protein-based machines are capable of stretching and shrinking under the appropriate signals to cause muscles to contract to propel movement, pump blood, or regulate the size of many of our internal organs.
What is more, the control of these sarcomeres rests on the interactions of electrical and chemical signals. Chief among the chemicals that are important to muscle contraction is calcium. The same substance that forms the basis of bone in the human body is also responsible for initiating contraction of sarcomeres.
Control of a contraction begins well before calcium is released into the cytoplasm of a cell, however. In skeletal muscle, the signal for a contraction is generated within the central nervous system as a nerve impulse. In the heart, specialized pacemakers cells are the impetus for a contraction. Finally, in smooth muscle, hormones, neurotransmitters, and even drugs can be the stimulus necessary to begin a muscle contraction. Each of these muscle types shares a great deal of physiology in common, but each also has its own unique properties that enable it to fulfill its special role in the body.
Understanding muscle contraction is essential to understanding human physiology. Fortunately, the three types of muscles share a great deal in common, so lessons learned about skeletal muscle can be applied to cardiac and smooth muscle. This book covers skeletal muscle first and then uses the knowledge gained from that topic to explain the differences and similarities in both smooth and cardiac muscle.