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in the terminal cisternae
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How does muscle contraction occurs?
Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same. Although the term contraction implies shortening, when referring to the muscular system, it means muscle fibers generating tension with the help of motor neurons (the terms twitch tension, twitch force, and fiber contraction are also used).
Which of the following become connected by myosin cross-bridges during muscle contraction A) thin filaments and thick filaments B) thin filaments and t-tubules C) thick filaments and titin filame?
Interactions between actin and myosin filaments of the sarcomere are responsible for muscle contractions. The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments.
What bridges cross the thames?
There are 107 bridges across the Thames - to many to name here
Describe the major events of muscle fiber contraction?
Muscle fiber contraction is a complex process involving a number of cell parts and chemical substances that result in the sliding movement of the actin and myosin filaments and causes a contraction. A myosin filament is composed of protein strands with globular ends called cross-bridges that extend outward along the length of the filament. The actin filaments have ADP molecules attached to its surface that serve as active sites for linking the cross-bridges of the myosin filaments. Although the process is not completely understood, the sliding filament theory suggests that the myosin cross-bridge attaches to an actin active site and bends slightly, pulling the actin with it. It releases its attachment, straightens, and combines with another active site further down the actin filament, causing the sarcomere to shorten. When the nerve impulse reaches the distal end of its branch, acetylcholine is released into the gap. The acetylcholine diffuses rapidly across the motor end plate and combines with protein receptors in the sarcolemma. This causes a muscle impulse to be generated and pass in all directions over the entire sarcolemma, and through the T-tubules deep into the fiber. The S.R., which contains a high concentration of calcium ions, becomes more permeable and allows the ions to diffuse into the sarcoplasm. When a high enough concentration is present in the sarcoplasm, the linkages between the actin and myosin filaments occur and contraction takes place. The calcium ions are moved quickly back into the S.R. by an active transport system (calcium pump). When enough calcium ions have been removed from the sarcoplasm, the muscle relaxes. At the same time, the acetylcholine is rapidly decomposed by the enzyme cholinesterase. This prevents a single nerve impulse from causing a sustained contraction.
How does Viagra work at a cellular level?
Viagra inhibits the enzyme that inhibits the production of cGMP. The purpose of cGMP is to activate Protein Kinase G which triggers muscle relaxation through the activation of phosphatase (an enzyme which removes a phosphate from smooth muscle myosin thus inhibiting cross bridges from being formed) and thus contraction is not permitted to happen. Basically through the use of Viagra cGMP can be active and this triggers a chain of events that allows the veins in the penis to dilate and thus an erection can occur.
When myosin cross bridges bind to actin what happens?
Muscle contraction results
What describes the events of contraction in excitation-contraction coupling?
cross bridge formation "Excitation-contraction coupling" connects muscle fiber excitation to the muscle fiber contraction (cross bridge formation). During contraction, myosin heads form cross bridges many times-with each cross bridge generating a small amount of tension in the muscle fiber.
What is the function of troponin in muscle contractions?
It is involved in the regulation of the contraction of a cross-striated muscle.
During skeletal muscle contraction myosin cross bridges attach to active sites of?
During skeletal muscle contraction myosin cross bridges attach to active sites of actin filaments. Actin filaments bind ATP. Their growth is regulated by thymosin and profilin.
What best describes the events of excitation in excitation-contraction coupling?
cross bridge formation "Excitation-contraction coupling" connects muscle fiber excitation to the muscle fiber contraction (cross bridge formation). During contraction, myosin heads form cross bridges many times-with each cross bridge generating a small amount of tension in the muscle fiber.
During muscle contraction myosin cross bridges attach to which active sites?
actin filaments
What does myosin attach to?
During muscle contraction, myosin cross bridges attach to active sites of ACTIN FILAMENTS.
What is the process of excitation contraction coupling?
cross bridge formation "Excitation-contraction coupling" connects muscle fiber excitation to the muscle fiber contraction (cross bridge formation). During contraction, myosin heads form cross bridges many times-with each cross bridge generating a small amount of tension in the muscle fiber.
What is the time in which cross bridges are active called?
contraction
What acts as ATPase during the contraction cycle of muscle?
myosin cross-bridges
How would the loss of acetylcholinesterase from the motor end affect skeletal muscle?
Acetylcholine release is necessary for skeletal muscle contraction, because it serves as the first step in the process, enabling the subsequent cross-bridge formation. A muscle's ability to contract depends on the formation of cross-bridges between myosin & actin filaments. A drug that blocks acetylcholine release would interfere with this cross-bridge formation and prevent muscle contraction
How would a drug that interferes with cross bridge formation affect muscle contraction?
a drug that interferes would prevent muscle contraction
