Search results
Results from the WOW.Com Content Network
Isotonic contractions differ from isokinetic contractions in that in isokinetic contractions the muscle speed remains constant. While superficially identical, as the muscle's force changes via the length-tension relationship during a contraction, an isotonic contraction will keep force constant while velocity changes, but an isokinetic ...
[14] For example, with the latissimus dorsi muscle, the origin site is the torso, and the insertion is the arm. When this muscle contracts, normally the arm moves due to having less mass than the torso. This is the case when grabbing objects lighter than the body, as in the typical use of a lat pull down machine.
When a sarcomere contracts, the Z lines move closer together, and the I band becomes smaller. The A band stays the same width. At full contraction, the thin and thick filaments overlap. Contraction in more detail. Contraction is achieved by the muscle's structural unit, the muscle fiber, and by its functional unit, the motor unit. [4]
during contraction, actin filaments move into the A bands and the H zone is filled up reducing its stretch, the I bands shorten, the Z line comes in contact with the A bands; and; the possible driving force of contraction is the actin-myosin linkages which depend on ATP hydrolysis by the myosin.
Depiction of smooth muscle contraction. Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [1]
The angle of pennation will increase during contraction accompanied by an increase in thickness. Thickness is defined as the area between the aponeuroses of the muscle. A low gear ratio occurs when the contraction velocity of the whole muscle and individual fibers is approximately the same, resulting in a gear ratio of 1.
A better estimate is provided by the total area of the cross-sections perpendicular to the muscle fibers (green lines in figure 1). This measure is known as the physiological cross-sectional area (PCSA), and is commonly calculated and defined by the following formula, developed in 1975 by Alexander and Vernon: [4] [5] [6]
Muscle is a soft tissue, one of the four basic types of animal tissue.Muscle tissue gives skeletal muscles the ability to contract.Muscle is formed during embryonic development, in a process known as myogenesis.