Muscle contraction
Muscle Contraction
Muscle contraction (/ˈmʌsəl kənˈtrækʃən/) is a process that occurs when the muscle fibers generate tension through the action of actin and myosin filament interaction. This process is responsible for the movement and maintenance of posture in the body.
Etymology
The term "muscle" comes from the Latin musculus, meaning "little mouse", possibly because of the shape of certain muscles or the way certain muscles move. The term "contraction" derives from the Latin contractio, meaning "a drawing together".
Process
Muscle contraction begins when the nervous system generates a signal. The signal, an impulse, travels through a type of nerve cell known as a motor neuron. The motor neuron then stimulates a muscle fiber, causing it to contract.
The actual process of muscle contraction takes place in the sarcomere, the basic unit of a muscle fiber. The sarcomere is composed of long, fibrous proteins that slide past each other when the muscles contract and relax.
Types of Muscle Contraction
There are three types of muscle contraction: isotonic, isometric, and isokinetic.
- Isotonic contractions are those in which the muscle changes length as it contracts and causes movement of a body part.
- Isometric contractions are those in which the muscle does not significantly change length while contracting and no movement is observed.
- Isokinetic contractions are those in which the muscle changes length while the contraction speed remains constant.
Related Terms
- Muscle fiber: The individual contractile units that make up a muscle.
- Myofibril: A basic rod-like unit of a muscle fiber.
- Sarcoplasmic reticulum: A network of membranes found within muscle fibers that is similar to the endoplasmic reticulum in other cells.
- Tropomyosin: A protein that works together with troponin to regulate muscle contraction.
- Troponin: A protein that works together with tropomyosin to regulate muscle contraction.
External links
- Medical encyclopedia article on Muscle contraction
- Wikipedia's article - Muscle contraction
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