Cardiac Muscle Contraction

Cardiac
This is an involuntary muscle, found solely in the walls of the heart, as well as in the walls of the blood vessels. This sort of muscle has similarities with the skeletal muscles, because it is striated. Furthermore, it has slight similarities to the smooth muscles, because its contractions are not under conscious control. On the other hand this type of muscle is highly specialised. It is under the control of the autonomic nervous system, however, even without nervous imput contractions can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing continuous aerobic metabolism.

Smooth
Smooth muscle, are also known as involuntary muscle due to our inability to control its movements, or Unstriated, because it does not have the stripy appearance of a skeletal muscle. Smooth muscles are found in the walls of hollow organs such as the Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal organs, for example, moving food along the Oesophagus or constricting blood vessels during Vasoconstriction.
Contractions that permit the muscle to shorten are referred to as concentric contractions. An example of a concentric contraction in the raising of a weight during a bicep curl. In concentric contractions, the force generated by the muscle is always less than the muscle's maximum. As the load the muscle is required to lift decreases, contraction velocity increases. This occurs until the muscle finally reaches its maximum contraction velocity. By performing a series of constant velocity shortening contractions, a force-velocity relationship can be