Muscle Contraction Research Paper

Muscle contractions are the way that humans are able to move within the enviornment that surrounds them. To be able to understand the complexity of movement, there needs to be an understanding of the gross and micro-anatomy muscle contraction, and an understanding of the physiology of muscle contraction. This paper will provide an explaination of both the anatomy and physiology of muscle contraction.

Anatomy of Muscle Contraction
There are three types of muslces within the human body: skeletal, cardiac, and smooth. There are many differences between each of these types of muscles, ranging from structure to how they actually contract. For the explination purposes, this paper shall focus on skeletol muscles, These muscles are striated (meaning
The tendon is fused with the periosteum of the bone. The tension from the interaction of the muscle and the tendon is transfered to the mysia, tendon, then the periosteum to pull the bone and create movement. In some locations of the body, the mysia may fuse with a broad tendon-like sheet called aponeurosis (fascia).
Due to the fact that skeletal muscles are long and cylindrical, they are reffered to as fibers. These fibers can be large for human cells with diameteres up to 100 μm and lengths up to 30 cm.
Physiology (and some Anatomy) of the Muscle Contraction
Within the muscle tissue there is a unique arrangement of myofilaments (actin and myosin) in a sequential order in the muscle fiber. Each packet of actin and myosin and their regulatory protiens (troponin and tropomysin and others) is called a sarcomere. The actin and its tropin-tropomyosin complex are thin strand referred to thin filaments. The myosin and its multiple heads are called the thick filament. Together they are referred to as Z-lines.
In order for the muscle to contract there are a series of physiological steps to activate the anatomical movement of the muscles:
1.) Excitment of the
Basically a signal goes along the axon terminal from the motor neuron at the spinal cord to the muscle fiber which will then be terminated at the NMJ. At the NMJ a neurotransmitter called acetylcholine (ACh) is difused along the the synaptic cleft and binds to ACh receptors along the motor end-plate of the sarcolemma. Once ACh is binded, a chanel within the ACh receptor opens and (+) ions (Ca++) can pass into the muscle fiber which depolarizes the membrane potential. As this happens the voltage-gated sodium channels are triggered opens and allows sodium ions (NaCl-) enters the fiber and action potential spreads along the entire membrane to initiate excitation-contraction coupling. Following the depolorization of the membrane, repolarization occurs, which reestablishes the negative membrane potential. The ACh within the synaptic cleft is also degraded by AChE so that ACh cannot rebind and reopen the channel. As stated above, Ca++ is diffused from the sarcoplasmic reticulum (SR) into the