Biological basis of human movement Essay Example | Topics and Well Written Essays - 1500 words

Biological basis of human movement - Essay Example These types of movements are not particularly powerful movements but an important one none the less. The tibialis is responsible for ensuring that the toes are lifted properly during the act of walking. Without this, the foot would constantly drag. The gastrocnemius on the other hand is made up of two thick muscle bellies (composed of muscle fiber bunches) and is responsible for flexing the foot while the knee joint is extended. Comparatively speaking, the gastrocnemius is a larger more powerful muscle than the tibialis anterior. The gastrocnemius is composed of more fibers and contains two muscle bellies as apposed to one. To better understand theses two specific muscles, one must first establish the cellular structure of muscle tissue. Muscular tissue is considered to be contractile or possessing an elastic property, similar to a rubber band. Muscles are made up of certain types of cells called muscle "fibers". These specific types of cells are composed of what is called actin filaments and myosin filaments. It is the interconnecting or interacting of these filaments that is responsible for muscle contractions. The specific types of muscles that this lab is concerned with are called skeletal muscles. These muscles can also be called striated muscles. The term "striated" is given them due to the thread like fibers that they are composed of, which are both light and dark. The appearance of light and dark in these muscle threads is due to the actin and myosin filaments. These thread like fibers cause the muscles to appear striped or "striated". Skeletal muscles are responsible for the movement of limbs and appendages. They are attached to the long bones via tendons. It is the angle that presents between the joint and the muscle that constitutes the angle of pennation that we will be studying. In the observation of these muscles, we need to understand their structure on a cellular level in order to fully comprehend their mechanisms. It is important also to know that each of the skeletal muscles that we are observing is made up of several muscle fibers (cells). These fibers are each a long cell with some unique cellular characteristics. One of the characteristics specific to muscle fibers (cells) is the sarcolemma. The sarcolemma is the plasma membrane to the muscle fiber (cell) with some very important features. It possesses what is called T tubules which are structures specifically for penetrating the cell itself in order to make contact with the sarcoplasmic reticulum. These tubules aim to touch the sarcoplasmic reticulum without actually connecting to it. The sarcoplasmic reticulum is much like an endoplasmic reticulum but an enlarged or expanded version. The sarcoplasmic reticulum is larger or expanded in muscle fibers in order to store calcium ions. Calcium ions are imperative to the contraction of muscles. The part of the muscle fiber responsible for contraction is called the myofibril. Structures called sarcomeres are located within these myofibrils. The sarcomeres contain protein filaments which is the core reason for muscle contraction. This is basically the contraction site of the muscle. The protein filaments are composed of the two filaments mentioned earlier, actin and myosin. The interaction of actin and myosin can be explained by what is called the Sliding Filament Theory. This theory states that