The fate of acetylcholine following binding 10. Describe skeletal muscle fiber contraction including: • The sliding filament mechanism • Excitation-contraction coupling • The cross bridge cycle • How muscle fiber contraction results in body movement 11 Describe skeletal muscle fiber relaxation and the resulting relaxation of an entire skeletal 14. Define the two abnormal contractions of skeletal muscles, cramp and spasm. 15. Describe muscle tone and state its importance to the health of the muscular system.
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Skeletal muscle fiber: Skeletal muscle fibers are long, cylindrical, multinucleated cells that make up the majority of skeletal muscles. They are composed of myofibrils, which contain the contractile proteins actin and myosin. Show more…
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In the disease tetanus, muscles undergo periods of spasm, in which they maximally contract and are unable to relax. During such a spasm, the muscles are in a state of sustained contraction. A scientist has produced a type of myosin that can bind ATP but has lost its hydrolyzing capability. What will be the state of a muscle that includes this myosin within its sarcomeres? You have been hit with a shrink-ray and have entered a muscle fiber to explore the action of a muscle at a microscopic scale. You move close to a myosin head and have to dodge a bit of inorganic phosphate that goes flying by. Which stage of the muscle contraction has this myosin filament just completed? What would be the outcome if you prevented the removal of calcium ions from the sarcoplasm into the sarcoplasmic reticulum? What describes the contraction of a muscle at the level of protein interactions? A muscle that is denied ATP will be unable to contract. A mad scientist is attempting to produce a paralytic agent to administer to their superspy nemesis. They have worked with a number of possibilities and have settled on interfering with proteins critical for muscle contraction. Recommend to the scientist a suitable means of achieving this goal. A new kind of vertebrate has been discovered with muscle fibers that lack t tubules. Predict a compensatory change in the microanatomy of the muscle fiber in comparison to the standard vertebrate condition. A muscle fiber has been exposed to anatoxin, an acetylcholine mimic that irreversibly binds to ACh-gated channels in cell membranes. What will happen to this muscle? How is a muscle contraction similar to the transmission of a stimulus to the central nervous system? A patient reports to a clinic with symptoms of muscle weakness and sluggish contraction. A test of nerve function revealed no neural disease, and there is no indication of any mitochondrial disease. What is a possible explanation for this patient's symptoms?
Adi S.
Below are steps of skeletal muscle excitation and contraction (i.e., excitation-contraction coupling). Arrange the statements in the correct order in which they occur. 1. very low calcium in sarcoplasm, actin and myosin unbound, troponin and tropomyosin in plasma 2. myosin heads firmly bound to actin 3. sodium rushes into muscle fiber, causing local depolarization, and the end plate potential (type of graded potential) 4. activation of L-type voltage-gated calcium channels 5. calcium binds troponin on sarcomeres of myofibril 6. muscle action potential travels down sarcolemma and t-tubules 7. motor neuron action potential travels down axon, stimulating ACh release from terminals 8. threshold is reached and muscle action potential is generated 9. ACh diffuses across synapse and binds to ligand-gated receptors at muscle end plate 10. calcium diffuses out of sarcoplasmic reticulum, raising concentration in sarcoplasm (End of Excitation Steps) 11. myosin quickly breaks phosphate bond of ATP 12. myosin heads weakly bind actin 13. ADP released from the ATP binding site of myosin 14. activation of calcium release channels 15. tropomyosin slides out of position, off myosin binding sites on actin 16. free phosphate group released from the ATP binding site of myosin 17. new ATP molecule binds to open ATP binding site of myosin 18. myosin heads swing forward, towards the M line of the sarcomere (i.e., power stroke) 19. myosin becomes re-energized and bound with ADP+P, ready to contract again and repeat the cycle
Muscle Contraction Worksheet Muscles will contract in response to a "message" from a motor neuron (nerve cell). Label the drawing with the correct parts of the neuron. Soma, axon, dendrite, terminal boutons (buttons), node of Ranvier, myelin sheath. Use this word list to fill in all the blanks below. Actin Action potential Acetylcholine Troponin Calcium channels Myosin Sarcoplasmic reticulum Tropomyosin Synaptic vesicles Transverse tubules Sarcolemma 1. An ______ travels down the length of the neuron's axon. 2. The Action Potential will cause ______ at the end of the axon to open. 3. Ca++ is in high concentration outside the cell & in low concentration inside the cell. Therefore, Ca++ diffuses into the axon. (Define diffusion. Does it require the input of energy?) 4. Ca++ influx causes ______ containing ______ (the neurotransmitter released at ALL skeletal muscles) to move to the axonal terminus, fuse onto the membrane, and release ACh from the neuron (exocytosis). 5. The binding of ACh to the ACh receptors on the motor end-plate initiates the formation of an action potential along the ______ of the muscle fiber!
Madhur L.
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