Prof. J.P.N. Mishra
Movements within the body take place because of the contraction of muscles. The important functions of muscles are -
- Movement of the body: Most skeletal muscles are attached to bones, are typically under conscious control, and are responsible for most body movements including walking, running, or manipulating objects with the hands.
- Maintaining the posture: Skeletal muscles constantly maintain tone, which keeps us sitting or standing erect.
- Process of respiration: Muscles of the thorax are responsible for the movements necessary for respiration.
- Heat generation: When skeletal muscles contract, heat is given off as a by-product. This released heat is critical to the maintenance of body temperature.
- Message transmission: Skeletal muscles are involved in all aspects of communication, such as speaking, writing, typing, gesturing, and facial expression.
- Constriction at tissue level: The contraction of smooth muscle within the walls of internal organs and vessels causes constriction of those structures. This constriction can help propel and mix food and water in the digestive tract, propel secretions from organs, and regulate blood flow through vessels.
- Heart Function: The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body.
Special Characteristics of Muscles: Muscle tissue is highly specialized to contract forcefully. The process of metabolism yields energy from nutrient molecules and some quantity of that energy is used for muscle contraction and the remaining is used for other cellular processes or is released as heat.
Properties of Muscles: Properties of muscles can be explained in four terms- (a) Contractility, (b) Excitability, (c) Extensibility, and (d) Elasticity.
- Contractility is the ability of muscle to contract with a definite. When muscle contracts, it causes movement of the structures to which it is attached, or it may increase pressure inside hollow organs or vessels.
- Excitability is the response of muscle against a stimulus.
- Extensibility is a phenomena when muscle can be stretched to its normal resting length.
- Elasticity is the ability of muscle to return to its original resting length after it has been stretched.
