10.1 General characteristics of muscles
10.2 Skeletal muscle contraction and relaxation
10.3 Physiological features of skeletal muscles
10.4 Physiological characteristics of smooth muscles
Profile materials Control questions Situational tasks
Function of the muscles. Muscles perform the following main functions: supporting posture and performing movements, which produce heat, providing mechanical protection of internal organs, building glycogen pool, providing reserves of proteins and water, performing the pumping action of the heart, maintaining vascular, respiratory and bronchial tone, controling digestion, urination, childbirth.
10.2. Skeletal muscle contraction and relaxation
10.1. General characteristics of muscles
Types of muscles. Muscles make up about 50% of body weight. The three basic types of muscle are skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscles are striated muscles that are under voluntary control (i.e., controlled by the central nervous system) and they play a key role in numerous activities such as maintaining posture, locomotion, speech, and respiration. Smooth muscles are found in blood vessels, hollow internal organs, etc.
Muscle properties. Muscles are characterized by their physical and physiological properties. Physical properties include elasticity and stiffness, tension (tone), and plasticity. Physiological properties include excitability, automation (in smooth and heart muscles), conductivity and contractility. In all three types of muscle, force is generated by interaction of actin and myosin, a process that requires transient elevation of intracellular Ca2+. Sources of calcium and the nature of interaction of actin and myosin filaments are different and depend on the type of muscle.