Questions and Answers
What is the meaning of the prefix myo-?
What is the meaning of the prefix epi-?
The structural and functional unit of skeletal muscle is called a/an:
What happens if a muscle fiber is extensible but not elastic?
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What would occur if actin filaments were incapable of sliding past the myosin filaments?
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If you consumed pufferfish that was not prepared correctly, what effect would it have on your muscle fibers?
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Which membrane protein is involved in active transport?
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If the cytosol loses K+ ions through leak channels, how will it change?
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For every ATP split into ADP and a phosphate, the Na+/K+ pump moves _____ out of the cell and ______ into the cell.
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What is the narrow space between the axon terminal and the motor end plate called?
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What happens when acetylcholine (ACh) receptors are stimulated by ACh?
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What is the end-plate potential?
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How does multiple sclerosis affect skeletal muscle stimulation?
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What is the result of an overdose of Botox?
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What are the components of a triad?
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What does excitation-contraction coupling lead to?
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What is the effect of Tetrodotoxin on action potential generation?
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When does a crossbridge form?
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Which step occurs immediately before the power stroke in the crossbridge cycle?
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What happens as myosin heads complete the power stroke?
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What causes myosin to detach from actin?
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In the absence of ATP in muscles, what is most likely to occur?
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What can cause muscle relaxation?
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What occurs when the sarcolemma repolarizes?
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What causes rigor mortis?
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Study Notes
Prefixes Related to Muscle Terms
- Myo- means "muscle."
- Epi- signifies "above," "upon," or "over."
- Sarco- refers to "flesh."
- Peri- means "around."
- Endo- denotes "within" or "inner."
Muscle Structure and Connective Tissues
- A sarcomere is the skeletal muscle's basic structural and functional unit.
- The perimysium is the connective tissue surrounding a fascicle.
- The epimysium covers the outer layer of the entire muscle.
- The endomysium surrounds an individual muscle fiber.
- Myofibrils are the contracting parts of muscle fibers.
Muscle Fiber Properties
- Extensibility allows muscle fibers to stretch, while elasticity enables them to return to their original shape; lack of elasticity means stretching without returning to form.
Muscle Contraction Mechanisms
- If actin cannot slide past myosin, muscle contraction and tension generation are impossible.
- Tetrodotoxin from pufferfish blocks sodium ion channels, preventing action potentials in muscle fibers and causing paralysis.
Ion Transport and Resting Potential
- The Na+/K+ pump is crucial for active transport across membranes.
- Loss of K+ ions through leak channels results in a more negative cytosol.
- For every ATP used, the Na+/K+ pump transports 3 Na+ out and 2 K+ into the cell.
Synaptic Transmission
- The gap between the axon terminal and motor end plate is called the synaptic cleft.
- Stimulation of acetylcholine (ACh) receptors leads to sodium ions entering the muscle fiber, resulting in depolarization known as the end-plate potential.
Impacts of Neural Conditions on Muscle Function
- Demyelination in conditions like multiple sclerosis blocks action potentials, preventing muscle contraction.
- An overdose of botulinum toxin blocks ACh release, causing muscle paralysis.
Triads and Calcium Dynamics
- A triad consists of two terminal cisternae of the sarcoplasmic reticulum (SR) and one T-tubule.
- Excitation-contraction coupling increases calcium ion concentration in the muscle fiber cytosol.
- Tetrodotoxin prevents action potential generation in muscle fibers.
Crossbridge Cycling
- A crossbridge occurs when a myosin head binds to actin.
- Formation of a crossbridge precedes the power stroke in the crossbridge cycle.
- During the power stroke, actin filaments slide toward the M line of the sarcomere.
Myosin and ATP Interaction
- Myosin detachment from actin is facilitated by the binding of ATP to myosin.
- In ATP absence, myosin heads remain attached to actin but cannot perform the power stroke.
- Muscle relaxation arises from the end of neural stimulation.
Resting Membrane Potential and Rigor Mortis
- After repolarization, the inside of the sarcolemma becomes more negatively charged than the outside.
- Rigor mortis, the stiffening of muscles post-death, results from ATP depletion and elevated cytosolic calcium, preventing crossbridges from detaching.
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Test your knowledge of muscle-related terminology with these flashcards. Each card covers important prefixes and the structure of skeletal muscle, including key definitions and functions.