Three Different Kinds Of Muscles : Skeletal, Cardiac And Smooth Muscle

1580 Words7 Pages
Introduction: The body consists of three different kinds of muscles: skeletal, cardiac and smooth muscle. Skeletal muscle, which is the primary focus of this lab, is made up of much smaller muscle fibers. These muscle fibers have smaller units called myofibrils followed by the smallest contractile unit of a muscle fiber called the sarcomere. Furthermore, the sarcomere is composed of two filament types- thick filaments, called myosin and thin filaments called actin. In order for muscle contraction to occur, these two filaments must bind to form cross bridges. These cross bridges are formed through the interaction of the actin and myosin head along with calcium ions and ATP molecules. The formation and reformation of these cross bridges is what is known as cross bridge cycling and is what is responsible for repeated muscle contraction in the same sarcomere. Muscle contractions only occur when they receive action potentials from nerve cells called motor neurons. These motor neurons synapse directly onto muscle cells- sometimes even innervating multiple muscle cells. If there is a need for stronger contraction, motor neurons can be recruited to aid in the increase of muscle contraction. A concept known as motor unit recruitment. Typically, motor unit recruitment goes from the smaller units, which innervate smaller muscles, to larger units which innervate larger muscles. This is known as the Henneman’s size principle. However, for the purposes of this experiment, when

More about Three Different Kinds Of Muscles : Skeletal, Cardiac And Smooth Muscle

Open Document