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Essay on skeletal and smooth muscle comparison
Exam question on muscle tissue types
Essay on skeletal and smooth muscle comparison
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Muscle tissue, made of up highly specialized cells for contraction, is one of the four basic tissue types in multicellular organisms. There are three types of muscle tissue: skeletal, smooth and cardiac. However, this essay will concentrate on comparing skeletal and smooth muscle, firstly in the way they are structured and secondly in their function.
Skeletal muscle is found in vertebral organisms and attaches to bone via tendons. Smooth muscle is found in blood vessel walls and lining the walls of visceral organs. Each type of muscle is structured to best provide the body with the movements it needs internally and externally. Almost every essential function in the body, whether it is breathing, digesting, controlling blood pressure or simply walking requires muscle tissue.
Both skeletal and smooth muscle use actin and myosin to build their contractile elements, however their arrangement is different. In both muscle types there are two types of filaments: thick and thin. Within skeletal muscle, actin and myosin are arranged in myofibrils. Thin filaments in skeletal muscle are formed from filamentous actin, nebulin, tropomyosin and troponin. The length of thin filaments is defined by nebulin to form filaments of 1µm in length (Martini). Thick filaments are composed of “about 300 myosin molecules, each made up of a pair of myosin subunits twisted around one another”. Myosin molecules bind to one another via their long tail, leaving the head free to bind to the nearest thin filament. Thick filaments also have a specific length of 1.6µm and between 10 and 12 µm in diameter (Martini). The arrangement of these myofilaments in myofibrils and repeating sarcomeres, gives skeletal muscle its striated and regular appearance, as shown in f...
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... T and I to move back in front of the myosin binding site, which prevents further cross bridges from forming.
In smooth muscle the myosin light chain has to be dephosphorylated to deactivate the myosin. This is done by the enzyme myosin light chain phosphatase and disrupts the interaction between the myosin and actin causing relaxation. MLCP is activated by a decrease in sarcoplasmic Ca2+.
Although the two main proteins, actin and myosin, that make the contractile nature of muscles are the same, their arrangement coupled with other proteins subsequently causes the overall structure to differ in many respects. The main function is essentially the same in every muscle type, however as the structure varies the function and resulting contraction is different. the way they contraction occurs is different. This shows how structure is adapted to function and vice versa.
In the beginning phases of muscle contraction, a “cocked” motor neuron in the spinal cord is activated to form a neuromuscular junction with each muscle fiber when it begins branching out to each cell. An action potential is passed down the nerve, releasing calcium, which simultaneously stimulates the release of acetylcholine onto the sarcolemma. As long as calcium and ATP are present, the contraction will continue. Acetylcholine then initiates the resting potential’s change under the motor end plate, stimulates the action potential, and passes along both directions on the surface of the muscle fiber. Sodium ions rush into the cell through the open channels to depolarize the sarcolemma. The depolarization spreads. The potassium channels open while the sodium channels close off, which repolarizes the entire cell. The action potential is dispersed throughout the cell through the transverse tubule, causing the sarcoplasmic reticulum to release
The protocol and conceptual overview of these procedures can be found under the header, “Properties of Skeletal Muscle” in NPB 101L Physiology Lab Manual Second Edition (Bautista & Korber, 2009, 9-17). The test subject for this lab was the Northern Leopard frog whose spinal cord and brain were severed. In order to carry out the experiments, the materials needed were one medium length surgical scissor, two hemostats and glass dissecting probes, a nine and four inch string, a cup of Ringers saline solution with an eyedropper, and a hook electrode. The software used to analyze and record the data was the BIOPAC system.
For the lab test part, in this case we can do a muscle biopsy on him. A muscle biopsy is a procedure that removes a small sample of tissue for testing in a laboratory. The test can identify the disease is caused by nerve or by the muscle atrophy.
Muscle fibers are cylindrical. They have a diameter around ten to one hundred micrometers and are generally a few centimeters long. Within each muscle cells, contains basal lamina of collagen and glycoproteins. Each fiber contains a structure called excitation-contraction coupling, which is used to make sure the each contractile stimulus is quickly and equally communicated throughout the muscle fiber.
Within skeletal muscle there are extremely small structures that form the muscle and allow contractions and movement to occur (epimysium, perimysium, endomysium, fascicles, fiber, sarcomere, sarcoplasmic reticulum and t tubules). These structures all play a role in protecting, connecting and transporting substances throughout the muscle fibers. They are also the main contributors to movement.
The walls of arteries are made up of three layers same as veins. Its inner endothelium is composed of epithelial cells which is very smooth. This layer helps minimise the friction. The tunica media provides strength and elasticity. It contains smooth muscles, collagen and large amount of elastic fibres.
James’s biopsy of his right gastrocnemius muscle would have shown a degeneration of the muscle or skeletal fibers due to the lack of dystrophyn. Another microscopic change that would be noticed is the accumulation of white blood cells. White blood cells have a very specific function which is to clear the damaged muscle fibers from the debris. Clearly, due to some of the muscle fibers being damaged other healthy fibers that have not been damaged appear denser. By having damaged muscle fibers, all the work rest upon the healthy fibers making them contract to the fullest due to the fact that the myosin and acting would have to overlap even more to make the muscle work.
Repair after a muscle is damaged happens through the division of certain cells who then fuse to existing, undamaged muscle fibers to correct the damage. Different muscle types take different amounts of time to heal and regenerate after it has been damaged. Smooth muscle cells can regenerate with the greatest capacity due to their ability to divide and create many more cells to help out. While cardiac muscle cells hardly regenerate at all due to the lack of specialized cells that aid in repair and regeneration. In skeletal muscle, satellite cells aid in helping restoration after injury. Along with muscles, tendons are very important structures within the human body, and they to can be damaged. However, tendon repair involves fibroblast cells cross-linking collagen fibers that aid in not only reinforcing structural support, but also mechanical support as well (“Understanding Tendon Injury,” 2005). While quite different from muscle repair, tendon repair involves the similarity of reestablishing d...
The skeletal system assists the muscular system to provide movement for the body. Certain muscles that are attached to bones contract and pull on the bones resulting in movement.
Thibodeau, G., & Patton, K. (1993). Chapter ten: Anatomy of the muscular system. In Anatomy and physiology (1st ed., p. 252). St Louis: MO: Mosby.
The sarcomere is found in structures called myofibrils which make up skeletal muscle fibres. Within the sarcomere there are various different proteins. One of the most significant, myosin is found in the thick filaments of the sarcomere. Although both cells contain myosin, it is important to highlight that smooth muscle cells contain a much lower percentage of myosin compared to skeletal muscle cells. Despite this, myosin filaments in smooth muscle cells bind to actin filaments in a manner similar to that in skeletal muscle cells; although there are some differences. For instance, myosin filaments in smooth muscle cells are saturated with myosin heads so that myosin can glide over bound actin filaments over longer distances, enabling smooth muscle cells to stretch further, whilst in skeleta...
The three functions of the skeletal system are to support, to allow movement, and to protect. The skeleton is the framework of the body and also cradles its soft organs, with it the body would be just a jelly mass it wouldn’t have no definite shape and would just collapse. It supports the softer tissues and provides points of attachment for more skeletal muscles to hold all of the parts of the body upright. For example, the bones of the legs as pillars to support the body trunk we stand up. It also supports the body against the pull of gravity. The skeletal allows movement. The skeletal muscle attached to the bones by tendons and uses the bones as a simple mechanical lever system to move the body and its parts. All together with the muscles
Myogenin is required for the fusion of myogenic precursor cells to either new or previously existing fibers during the process myogenin and has been observed to induce myogenesis in non-muscle cell type as well. Mcf2 (MCF.2 cell line derived transforming sequence) is a nucleotide exchange factor proteins that stimulate the exchange bound to other proteins, (Laclef 2003) indicates Six (Transmembrane Epithelial Antigen Of Prostate 1) is a gene found in the prostate tissue, MyoD (Family inhibitor) is a transcription factor that negatively regulates myogenic family proteins it interferes with myogenic factors by masking (NLS) nuclear localization the amino acid fusion that bonds to proteins that import into the cell nucleus via nuclear transport this consist of one or more short positive charges on the protein surface so MyoD’s negative regulation would prevent DNA binding also Myf6 (Herculin) Myogenic Factor 6 it’s another indespecible regulatory factor in the myogenesis
The contraction of a muscle is a complex process, requiring several molecules including ATP and Cl-, and certain regulatory mechanisms [1]. Myosin is motor protein that converts chemical bond energy from ATP into mechanical energy of motion [1]. Muscle contraction is also regulated by the amount of action potentials that the muscle receives [2]. A greater number of actions potentials are required to elicit more muscles fibers to contract thus increasing the contraction strength [2]. Studied indicate that the larger motor units, which were recruited at higher threshold forces, tended to have shorter contraction times than the smaller units [3]. The aims of the experiment were to reinforce the concept that many chemicals are required for skeletal muscle contraction to occur by using the rabbit muscle (Lepus curpaeums) [2]. In addition, the experiment was an opportunity to measure the strength of contraction and to observe the number of motor units that need to be recruited to maintain a constant force as the muscles begin to fatigue [2]. Hypothetically, the rabbit muscle fiber should contract most with ATP and salt solution; and the amount of motor units involved would increase with a decreasing level of force applied until fatigue stage is reached.
It is like a bone however, the bone is more rigid. It allows some movement as well as providing stability which is better than the actual muscle. The material with a specialised structure is created by cells, which are called Chondroplasty. This is also important as it helps movement and reduce friction. There’s a large about of flexibility in the tissue as they are elastic fibre which, give a large amount of strength.