Three Different Kinds Of Muscles : Skeletal, Cardiac And Smooth Muscle

This activity is the critical driving force of muscle contraction. The stream of action potentials along the muscle fiber surface is terminated as Acetylcholine at the neuromuscular junction is broken down by acetyl cholinesterase. The release of Calcium ions is ceased. The action of the myosin molecule heads is obstructed because of the change in the configuration of troponin and tropomyosin due to the absence of calcium ions. This will eventually cause the contraction to be ceased. Together with these physical processes, an external stretching force such as gravity pulls the muscle back to its normal length.

Smooth muscle contraction occurs when calcium is present in the smooth muscle cell and binds onto calmodulin to activate myosin light chain kinase (Wilson et al., 2002). Phosphorylation of myosin light chains result in myosin ATPase activity thus cross-bridge cycling occurs causing the muscle to contract (Horowitz et al., 1996). There are two known models of excitation and contraction in smooth muscle, electromechanical coupling (EMC) and pharmomechanical coupling

Introduction: According to the “Human Physiology Laboratory Manual “,BIOL 282 ,page 31 , the reason of performing this experiment is to learn how the muscle contraction occurs based on the molecular level and what kind of factors are involved .As a matter of fact, skeletal muscles contain a lot of nuclei because of the cell fusion while being developed and are made of cylindrical cells that have myofibrils. The myofibrils contain sarcomeres and the

O B J E C T I V E S 1. To define these terms used in describing muscle physiology: multiple motor unit summation, maximal stimulus, treppe, wave summation, and tetanus. 2. To identify two ways that the mode of stimulation can affect muscle force production. 3. To plot a graph relating stimulus strength and twitch force to illustrate graded muscle response. 4. To explain how slow, smooth, sustained contraction is possible in a skeletal muscle. 5. To graphically understand the relationships between passive, active, and total forces. 6. To identify the conditions under which muscle contraction is isometric or isotonic. 7. To describe in terms of length and force the

Actin and myosin filaments can be found in skeletal muscle and are the smallest units that form a sarcomere, which is the smallest contractile unit in muscle (Baechle, 2008). The Sliding Filament Theory states that the actin filaments slide inward on the myosin filaments, pulling on the boundaries of the sarcomere, causing it to shorten the muscle fiber, also known as a concentric muscular contraction (Baechle, 2008). The Sliding Filament Theory is composed of five steps: the “Resting Phase”, the “Excitation-Contraction Coupling Phase”, the “Contraction Phase”, the “Recharge Phase”, and the “Relaxation Phase” (Baechle, 2008). During the Resting Phase, the actin and myosin filaments are lined up with no cross-bridge binding of the two filaments. During the Excitation-Contraction Coupling Phase, Calcium is released from the sarcoplasmic reticulum and binds to troponin, causing a shift in tropomyosin where the binding cites are exposed (Baechle, 2008). When the binding cites are exposed, the myosin cross-bridge head attaches to actin. During the Contraction Phase, ATP bonds break, releasing energy that is used to allow the myosin head to flex, causing the actin filaments to move toward the M-bridge. During the Recharge Phase, there is a continuous repetition of the Excitation-Contraction Coupling Phase and the Contraction Phase in order to produce muscular

Introduction: Skeletal muscle contraction happens when Ca2+ floods into the muscle cell binding with troponin allowing actin and myosin to bind. The actin and myosin cross bridges bind and contract using ATP as energy. Muscle fatigue is defined as the inability to maintain a desired power output. Muscle contraction can be affected by peripheral fatigue which refers to fatigue mediated by factors outside of the central nervous system, specifically within the muscle fibers, or central fatigue which involves the central nervous system and occurs predominantly due to afferent reflexes that inhibit output from the motor cortex. Peripheral fatigue can be caused by decreased levels of any of the molecules/metabolites involved in muscle contraction.

-Muscles contract in a repeated pattern of binding and releasing between the two thin and thick strands of the sarcomere. ATP is critical to prepare myosin for binding and to recharge the myosin. The source

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

650 muscles operate the body. The voluntary Skeletal Muscles are long, slender, multinucleate disks with obvious striations have T-tubules utilizing actin and troponin. All muscles need Ca2+. These aerobic and non-aerobic muscles obtain Ca2+ from the sarcoplasmic reticulum (SR). The, intrinsic system, ANS, hormone regulated, voluntary, aerobic muscle of the heart get their Ca2+ from SR and Extra Cellular Fluid(ECF). They utilize the same site of calcium regulation as smooth muscle and contain intercalated disks. Smooth muscle, also voluntary, SR and ECF, aerobic, utilizes calmodulin in the cytosol for its source of Ca2+.

Muscle contraction starts with an electrical "go" signal from your brain. It stimulates the SR to open its calcium gates, flooding the myofilaments with calcium. The rise in calcium concentration causes the myofilaments to alter form and abbreviate. The coincidental shortening of myofilaments give rise to contraction.

Muscles use electricity to contract. Cells engender a voltage difference by altering the concentration of ions (Sodium and Potassium) called electrolytes. Theses electrolytes are additionally referred to as salts. Without the ions there is no cellular potential difference. The electrical signal activates what are called cross bridges by sanctioning Calcium to contact the thin filament of the sarcomere, this is where the ATP comes in. Cross bridges are minuscule golf club like proteins that are on the cessation of the thick filaments of the sarcomere. ATP is bound to the ATPase domain of the cross bridge. When ATP is hydrolyzed (makes ADP and Phosphate) it changes conformation (which designates shape) and affixes to the actin portion of the

Mentioned earlier the differences between smooth muscle and skeletal muscle is in the way actin and myosin is used during contraction, and the characteristics of the muscle cell as well. Skeletal muscles have long strands of multinucleate cells and are made of sarcomeres that form the striations within the cells. While smooth muscle, cells are not striated because they do not have sarcomeres and have a single nucleus. In addition, skeletal muscles are the only muscle cells out of the three that is voluntary. The third type of muscle cell is a cardiac muscle cell. Cardiac cells are quite different in the fact that they create branches, have a single central nucleus, are cross-striated and are only found in the heart, however they are more similar

3. How can you explain the increase in force that you observe? the increase is how many volts went into the muscle.

Contents Page Introduction 4 In Brief: Skeletal Muscle, Cardiac Muscle & Smooth Muscle Image 1.0 Anatomy Of Smooth Muscle Table – Basic Muscle Comparison 5 Note: See Appendix For Further Detail. Image 1.1 Muscle Cell Variations Image 2 Stimulus Transmission Image 3 Axon Junction 6 Events At The Neuromuscular Junction And Of A Synaptic Transmission Skeletal Muscle

Both of these muscles expand and contract as they have complex structures so it is essential how they do this. The cardiac muscle needs the contractions to occur in order to pump blood out of the atria and into the ventricles and round the circulatory system so the structure of this muscle shows the systole of the heart. The contractions of the skeletal muscle also depend on its structure. The binding and releasing of two strands of sarcomere is how the repeated pattern of contractions occurs. ATP is used to prepare myosin for binding to allow the contractions to happen. The skeletal and cardiac muscle also both has elasticity. The elasticity is used to restore the muscles back to their original lengths which enable them to resume back to their original length once they have contracted and been stretched.