Describe the properties and functions of the smooth, skeletal and cardiac muscle. (b)Explain the sliding filament hypothesis of - Assignment Example

Download file to see previous pages The arrangement of these cells to form a muscle tissue is also unique as they do not form a syncytium but they contract individually or as group of cells. This property of smooth muscle allows it to contract slowly in a wave like motion making it a suitable for gastrointestinal tract. Circular and longitudinal muscles are two smooth muscles found throughout the GIT tract and are responsible for peristalsis. Smooth muscles also line the walls of the blood vessels. They play an important role, especially in the arterioles, by constricting or dilating the blood vessel thereby controlling the flow of blood. Smooth muscles are also crucial in bigger blood vessels, such as aorta, and enable them to withstand high pressure generated during systole or ventricular contraction. (Clark, 2005, p. 139) Skeletal Muscle: These are the muscles under voluntary control. Skeletal muscle is also sometimes referred to as striated muscle but this term should be avoided as cardiac muscle is also a striated muscle and leads to ambiguity. A cell of skeletal muscle is very long, up to 30cm in length, and has a cylindrical shape. The cross section size of these cells is about 10-100 micrometer. It is not surprising that cell of this length has multiple nuclei for support and survival. But these nuclei are not located at the center and rather aligned at the periphery. This is because the contractile components in the cell cytoplasm push these nuclei towards the call border. Skeleton muscles form bulk of a human body and perform various functions. They are essential for locomotion and to perform any movement of the body. Although, skeletal muscles are mostly under voluntary control they also take part in a reflex arc that does not involve the higher centers and, therefore, is an involuntary process. The contractions produced by skeletal muscles are forceful and quick as compared to the smooth muscle. (Clark, 2005, p. 139) Cardiac Muscle: Cardiac muscle is a specialized tissue perfectly adapted to perform its function. It is the only muscle that is found in the heart. A very special property of a cardiac muscle is that is can contract on its own which mean it does not require an external stimulation. Certain specialized cardiac cells found in the sinus node, atrioventricular node and conducting fibers are capable of initiating an action potential and set up a particular rhythm for contraction of surrounding muscle cells. Due to these properties they are referred to as pace makers of the heart. Cardiac cells are arranged in a syncytium that helps them in conducting the electrical signals more efficiently. Moreover, these cells are joined to each other by special intercalated disks. These intercalated disks are actually fused cell membranes with gap junctions. Gap junctions allow fast sharing of cytoplasmic contents and help in the progression of electrical signals across this syncytium. The function of cardiac muscle is to set up its own rhythm and provide force required to pump blood throughout body’s circulation. Sliding filament hypothesis of muscle contraction: The cytoskeleton and its arrangement are unique in myofibers as compared to other places in our body. The entire length of myofiber is studded in the center with large structures called myofibrils. These myofibrils are composed of two types of myofilaments; thick myofilaments and thin myofilaments. Thick myofilaments are made up of a protein called myosin. This protein has a special shape that is vital for its ...Download file to see next pagesRead More