Types Of Muscle And Muscle Fibers

Skeletal Muscle Structure.The cells of skeletal muscles are long fiber-like structures. They contain many nuclei and are subdivided into smaller structures called myofibrils. Myofibrils are composed of 2 kinds of myofilaments. The thin filaments are made of 2 strands of the protein actin and one strand of a regulatory protein coiled together. The thick filaments are staggered arrays of myosin molecules.

Myofibrils are made up of long proteins that include myosin, titin, and actin while other proteins bind them together. These proteins are arranged into thin and thick filaments that are repetitive along the myofibril in sectors known as sarcomeres. The sliding of actin and myosin filaments along each other is when the muscle is contracting. Dark A-bands and light I-bands reappear along myofibrils. The alignment of myofibrils causes an appearance of the cell to look banded or striated. A myofibril is made up of lots of sarcomeres. As the sarcomeres contract individually the muscle cells and myofibrils shorten in length. The longitudinal section of skeletal muscle exhibits a unique pattern of alternating light and dark bands. The dark staining, A-bands possess a pale region in the middle called the H-zone. In the middle of the H-zone the M-line is found, that displays filamentous structures that can join the thick filaments. The light-staining bands also known as I-bands are divided by thin Z-line. These striated patterns appear because of the presence of myofibrils in the sarcoplasm (IUPUI, 2016).

I think anatomical and metabolic makes where fast, slow and intermediate muscle fibers. The type one makes it where it is red in the color in the myoglobin. This fiber arc needs to be rich in this mitochondria and oxidative enzymes because it is where a poor in phosphorylases this is because it makes a well-developed aerobic metabolism and this where the slow fiber makes it to where its highly resistant to where you can become fatigue. Features that can summarized the slow muscle are the large enough amounts of myoglobin to so many mitochondria to having to many blood capillaries and having to generate atp by having the aerobic system to hence term to oxidative fibers to where splitting ATP to the slow rate. To having the slowest contraction velocity to

As per the sliding fiber hypothesis, the myosin thick fibers of muscle strands slide past the actin thin fibers amid muscle compression, while the two gatherings of fibers stay at generally steady length.a new idea called cross-connect hypothesis traditionally swinging cross-connect, now for the most part alluded to as cross-connect cycle which clarifies the atomic system of sliding fiber. Cross-connect hypothesis expresses that actin and myosin frame a protein complex traditionally called actomyosin by connection of myosin head on the actin fiber, accordingly shaping a kind of cross-connect between the two fibers. These two corresponding speculations ended up being the right depiction, and turned into a generally acknowledged clarification

There are proteins other than myosin in the thick filaments of are muscle species. Hu, et. al.

The next form of muscle fiber is smooth muscle fiber, these fibers are considerably smaller than skeletal muscle fibers. A single smooth muscle fiber is thirty to two hundred micrometers long, thick centered and tapered at the ends. These smooth muscle fibers have a single nucleus that is centrally located and oval in shape. Smooth muscle fiber contains thick filaments and thin filaments. These filaments are in ratios of 1:10 and 1:15, but are not

Myofibril: cylindrical organelle running the length of the muscle fiber, containing Actin and Myosin filaments

The sliding filament theory of a muscle action has five phases. The first phase is resting. In this phase there is no calcium available to bind the myosin to the actin. This is the normal state of the muscle until activated by the excitatory phase. During this second phase, the sarcoplasmic reticulum becomes stimulated. This releases calcium ions and binds with troponin. This is a protein that is strung along the actin filaments. Tropomyosin runs along the actin filaments. The actin is pulled closer to the sarcomere. The contraction phase is when it gets interesting. ATP is broken down into ADP in order to create energy for the contraction. To return to the normal state of the muscle, ATP replaces ADP and aids in detachment of the myosin cross

Myosin is the protein that moves beside the actins filaments that is within the sarcomere of muscle fibers, in which will create a contraction as it slides past one another. Myosin and actins makes up actomyosin, which is a protein complex found in muscle fibers. Before a contraction occurs, stimulation or sensory excitement must be present with a potential action of a nerve that connects to a muscle. However, the nerve connected to the muscle does not exhilarate fully, but to a few muscle fibers. It reacts to a sensory excitement in each sarcomere that is between the actin and myosin as the impulses reach the muscle fibers. When the muscles are being utilized, myosin will need large amounts of ATP. Once the sacromeres shorten, the muscles contract. Without the skeletal muscle tissue contractions, humans wouldn’t be able to walk, bite, or carry

During a stretch when the muscle is under contraction the myosin pulls the actin to the centre of the sarcomere, this is the basic concept of contraction. The myosin and actin overlap causing them to become bigger as the stretch carries on, refer to figure 4 for the contracted muscles diagram. The overlap between the myosin and actin becomes slacker and the fibres are able to elongate. Figure 4 demonstrate this exact action as the muscle becomes relaxed and elongates. When a muscle is stretched, it is extended to its maximum length: sarcomere to sarcomere, the muscle fibres will reach its maximum resting length, which causes additional tension. The connective tissue which is the tissue that surrounds the fascicles take up the slack, spreading tension throughout the muscle creating a line of tension. The disarranged muscle fibres straighten up in the line of tension, figure 4 displays the stretched form the muscle through a diagram with labelling. This is curial to the restoration of tissue in the specific muscle targeted for

The Musculoskeletal system is under the control of the nervous system and is responsible for human movement; this is comprised of the skeletal and muscular system, with the human body containing 640 skeletal muscles (Watkins 2010). Skeletal muscle is made up of muscle fibres (myofibres) and contain multiple nuclei; within the cytoplasm of these cells, there are long chains of myfibrils which are chains of many sarcomeres and these run from end to end of the muscle. Sarcomeres are comprised of thin and thick bands of proteins called actin and myosin; which overlap when a muscle contraction occurs; shortening the sarcomere (Edmiston 2012).

Myosin is a conventional term used to reference a group of molecular motors that translocate actin filaments or translocate vesicles on fixed actin filaments in living organisms[1]. The human genome also contains 24 unconventional Myosins divided into 11 distinct classes including some nonmuscle Myosins[2]. This poster will cover in particular Myosin II which is responsible for skeletal muscle contraction[1]

It has been known that contractile ring (CR) is composed of two major proteins F-actin and myosin II. This CR formed under the plasma membrane and the cytokinesis is happened based on the contraction of this CR. Therefore, many studies are attributed the CR contraction to the sliding-filament theory which explain the contraction in muscle sarcomeres (1,2). However, there are many differences in the organization of the actomyosin in CR and sarcomere. For example, F-actin in CR can organized in parallel manner and in disordered network compared to its antiparallel organization in sarcomere (3-5). In addition, the dependency of cytokinesis on myosin II has a wide variances compared to the dependency of sarcomere contraction on myosin II. For example, the current study showed that myosin II is a critical factor for contraction in cytokinesis (6). Ma et al (2012) proved that using of an engineered myosin II which lacks motor activity is enough for the CR contraction (7). In the budding yeast, the cytokinesis is driving mainly by F-actin disassembly (8,9).

Skeletal muscle consists of long cylindrical cells which, under a microscope, appear to be striated with bands throughout length of the cell. The nuclei of the multinucleated cells, located along the plasma membrane, lie along the periphery of the cell, thus forming swellings which are visible through the sarcolemma. The plasma membrane of the muscle cell, also known as sarcolemma, is densely invaginated by transverse tubules that saturate the cell. The cytoplasm, or sarcoplasm of the muscle cell, contains a calcium- storing sarcoplasmic reticulum, which is the specialised endoplasmic reticulum of a muscle cell. For the vast totality of the volume, the cell is filled with

A muscle is composed of numerous strands of tissue, referred to as fascicles. Each one of these fascicles are made up of bundles of muscle fibers (Lynn Hetzler). The muscle fibers are then made up of tens of thousands of myofibrils. Myofibrils are thread-like structures that are able to contract, relax, and stretch. Sacromeres, which are millions of thick and thin myofilaments laid end-to-end,