“Muscles are in a most intimate and peculiar sense the organs of the will. They have built all the roads, cities and machines in the world, written all the books, spoken all the words, and, in fact done everything that man has accomplished with matter.” (Hall, 1906.) The fundamental importance of muscular tissue in human beings is irrefutable as eloquently illustrated by G. Stanley Hall above. Muscle forms the largest group of tissue in the body, comprising of approximately 36% and 10% of body weight in skeletal and smooth muscle respectively. (Sherwood, 2009: 257) Fundamentally, there are a few similarities between skeletal and smooth muscle but these basic similarities aside, skeletal and smooth muscle are highly divergent. Skeletal muscle is striated in appearance, with several levels of muscular organisation providing structure. Functionally, muscle contraction in skeletal muscle occurs with the “sliding filament mechanism”, of which “excitation-contraction coupling” plays a pivotal role. (Sherwood, 2009: 261,264). Conversely, smooth muscle cells are unstriated, with elongated nucleus and arranged in sheets as seen in Figure 1. (Sherwood, 2009: 289) Smooth muscle function is diverse and its uses of Ca2+ ions in “excitation-contraction coupling” unique.
Elongated nucleusDespite so many differences between smooth and muscle cells, an understanding of their similarities will provide insights into muscle’s role in the human body.
Both skeletal and smooth muscle cells consist of thick myosin and thin actin filaments, their cross-bridges are activated by Ca2+ ions and both muscles require adenosine triphosphate (ATP) for activation. (Sherwood, 2009: 290-291) These similarities are fundamental to both types of muscle cells bu...
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...y Bretscher, Hidde Ploegh, Angelika Amon, Matthew P. Scott, Harvey Lodish (2012). Molecular Cell Biology. USA: W.H.Freeman and Co. Ltd.
Hall, G. Stanley (1907). Youth: Its education, regimen, and hygiene. USA: D Appleton and Company. p7-28.
Yawen Ju et al. (2013). Troponin T3 expression in skeletal and smooth muscle is required for growth and postnatal survival: Characterization of Tnnt3tm2a(KOMP)Wtsi mice. Genesis. 51 (9), p667-675.
Hideaki Karaki et al. (1997). Calcium Movements, Distribution, and Functions in Smooth Muscle. Pharmacological Reviews. 49 (2), p157-230.
Carlos M. Moran et al. (2008). Expression of the fast twitch troponin complex, fTnT, fTnI and fTnC, in vascular smooth muscle. Cell Motility and the Cytoskeleton. 65 (8), p652-661.
Lauralee Sherwood (2008). Human Physiology: From Cells to Systems, Seventh Edition. 7th ed. Canada: Brooks/Cole. p257-294.
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
Marieb, E. N., & Hoehn, K. (2013). Human anatomy & physiology (9th ed.). Boston, MA: Pearson.
Heart (Cardiac Muscle) Cells. Question 1: Briefly describe, in 500 words or less, the normal structure and function of your chosen cell type. In your answer, discuss specific features of your chosen cell type, including cell organelles. Throughout the heart, cardiac muscle cells are connected together to form a large network from one end to the other.
Every day we use our skeletal muscle to do simple task and without skeletal muscles, we will not be able to do anything. Szent-Gyorgyi (2011) muscle tissue contraction in rabbit’s muscles and discovered that ATP is a source for muscle contraction and not ADP. He proposed a mechanism to cellular respiration and was later used by Sir Hans Krebs to investigate the steps to glucose catabolism to make ATP. In this paper, I will be discussing the structure of muscle fibers and skeletal muscles, muscle contraction, biomechanics, and how glucose and fat are metabolized in the skeletal muscles.
Marieb, E. N., (2006). Essentials of human anatomy and physiology. San Francisco, CA: Benjamin Cummings.
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...
Schulman, Joshua M., and David E. Fisher. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 28 Aug. 0005. Web. 24 Apr. 2014.
Huether, S.E. & McCance, K.L. (2008). Understanding pathophysiology (4th ed.). St. Philadelphia, PA: Mosby Elsevier
is the biggest of all. Myocardial Infarction is a disease later read about in this report. The pericardium is a fibrous sac which is very smooth lining. In the space space between the pericardium and epicardium is a small amount of fluid. This fluid makes the movement of the heart muscles smooth. Myocardium is the heart muscle itself.
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...
Phelan, J. (2011). What Is Life? A Guide To Biology with Physiology. New York: Peter Marshall.
Upon stimulation by an action potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere. The best proposed model for understanding contraction is the sliding filament model of muscle contraction. Actin and myosin fibers overlap in a contractile motion towards each other. Myosin filaments have club-shaped heads that project toward the actin filaments.
The cytoskeleton is a highly dynamic intracellular platform constituted by a three-dimensional network of proteins responsible for key cellular roles as structure and shape, cell growth and development, and offering to the cell with "motility" that being the ability of the entire cell to move and for material to be moved within the cell in a regulated fashion (vesicle trafficking)’, (intechopen 2017). The cytoskeleton is made of microtubules, filaments, and fibres - they give the cytoplasm physical support. Michael Kent, (2000) describes the cytoskeleton as the ‘internal framework’, this is because it shapes the cell and provides support to cellular extensions – such as microvilli. In some cells it is used in intracellular transport. Since the shape of the cell is constantly changing, the microtubules will also change, they will readjust and reassemble to fit the needs of the cell.
Thibodeau, G & Patton, K. (2008) Structure and Function for the Body. 13th Edition. St. Louis: Mosby Elsevier.
Hoehn, K. & Marieb, E. N. (2007). Human Anatomy & Physiology, Seventh Ed. San Francisco, CA: Pearson Education, Inc.