Passive Forces In Muscle Movement

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Passive Forces in Limb Movements: Help or Hindrance
Introduction
Most animals are enabled to move because of contractions and relations of muscles. Vertebrates and invertebrates movement is initiated by a combination of both passive and active forces (Linke, Granzier and Kellermayer, 2003). Passive forces in muscles are forces that develop when an inactive muscle is stretched from its resting length in resistance of the induced stretch. Passive force in the limbs movement of both vertebrate and invertebrates is the compensation force of the active force induced in the muscles to cause movement. They are unintentional forces that take place in the animals’ bodies. Passive forces originate in muscles, tendons and other tissues of animals (Nigg,
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The muscles are a structure in ways that they have myofilaments that form sarcomeres. The sarcomeres form the basic unit of striated muscles that enable the muscles to perform their functions effectively. The fibers making the sarcomeres are made of proteins, and this is the points where muscles contracts and relaxes. The contraction and relaxation of the muscles lead to the movement of the limbs. Energy is required in the allowing the muscles to contract or relax. The source of energy in muscles is called adenosine triphosphate. The fibers making up the muscles link with adenosine triphosphate to obtain the energy required to allow the muscles to contract and relax (Dickinson, 2000). The fibers after obtaining the energy and receiving the necessary signal, they perform the required action. In the limbs, the signals are to allow movement or stop movement depends on the concentration of the intercellular calcium ions. Around the limbs, the muscles contain a very elastic protein known as titin (Ting, 2012,). Titin acts as a spring board that is responsible for passive forces. It is made up of 224 folded protein domains that unfold and refold whenever the forces causing unfolding is removed. Titin is very important in the passive forces; it controls the extent of movement of the sarcomere during active forces that make it expand. The amount of titin in the muscles depends on the …show more content…
Two muscles control the leg joints are attached opposite to each other of a lever. The two muscles are the flexor tibiae and extensor tibiae. In locust, though the two muscles are responsible for the flexing of the limb, passive forces exist and enhance the effect of the two opposing muscular forces. Passive force resists the extensor muscle, and if the muscle is relaxed the force would lead to movement of the leg. In the resting angle of a locust limb, there is a more passive force in the extensor tibiae than the flexor tibiae (Ache and Matheson, 2013). This clearly shows that the passive force in the locust joint originates from the muscles mostly the large extensor tibiae muscles. There were passive forces in the locusts that originated from the joint capsule of the limb. In other insects, the passive force still originates from the muscles and the joints of the limbs (Page et al., 2008). The passive forces allow the insects to have the flexed normal way of their life and the passive force at this point tends to be high. The extensors and the flexor tibiae in locusts give the origin of the passive force in their movements (Ache and Matheson, 2012). In the stick insects, the mechanisms of the structure play a very big part in the bringing up of the passive forces. The structure of the insects determines their passive forces that are observed in the movements and the relaxation of the

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