Plan
► Kinds of muscle tissues in human organism. Physical and physiological properties of muscle tissue. Comparative characteristics of striated and smooth muscle tissues.
► Motor unit. Classification.
► Modern concepts of mechanism of muscle contraction.
► Kinds and modes of muscle contraction. Theory of tetanic contraction.
► Fatigue in muscle tissue.
Kinds of Muscle Tissues in Human Organism. Physical
and Physiological Properties of Muscle Tissue. Comparative
Characteristics of Striated and Smooth Muscle Tissue
One of the most common manifestations of excitation in excitable tissues is a change in length, or contraction. An ability of tissue to change its length is based on the property of contractility best seen muscle tissue.
There are distinguished striated and smooth muscle tissues. Smooth muscle tissue is primarily found in the internal hollow organs: e.g., in the muscle layer of the walls of blood vessels, of digestive tract, urinary bladder, uterus and of some other organs. Striated muscles form the basis of skeletal muscles. A special kind of striated muscle tissue is cardiac muscle.
Striated Muscle Tissue of Musculoskeletal System
Any skeletal muscle consists of three types of muscle fibers:
► fast phasic muscle fibers called ?white? fibers due to a relatively low content of myoglobin pigment;
► slow tonic muscle fibers called ?red fibers? due to a relatively high content of myoglobin that gives them red coloring;
► receptor fibers.
The main function of the first two groups of fibers is to change the length of muscles: they participate in formation of muscle tone and in different kinds of fast (phasic) contractions, and are collectively called extrafusal muscle fibers. Receptor fibers are intrafusal muscle fibers.