Muscle Mayhem
What are the three types of muscle tissue?
Skeletal, Smooth, and Cardiac.
What neurotransmitter is released into the synaptic cleft to initiate muscle contraction?
Acetylcholine (Ach).
What type of filament contains the protein actin?
Thin filaments.
What energy molecule is required for muscle contraction?
ATP.
What are the three phases of a muscle twitch?
Lag/latent, contraction, relaxation
Which property of muscle tissue allows it to respond to an electrical stimulus?
Excitability.
What is the name of the gap between the axon terminal and the muscle fiber?
Synapse Cleft.
Which protein binds to Ca2+ to initiate cross-bridge cycling?
Troponin.
How is ATP generated quickly for initial muscle contraction?
Creatine Kinase.
In which phase of a muscle twitch does calcium release from the sarcoplasmic reticulum?
Contraction phase.
What is the difference between tendons and ligaments?
Tendon: Attach muscle to bone
Ligament: Attach bone to bone
What process happens at the sarcolemma after ACh binds to its receptor?
Na+ ions enter, causing local depolarization and producing an end-plate potential.
During a contraction, which protein pulls actin toward the center of the sarcomere?
Myosin.
What is the primary energy pathway used during sustained low-intensity exercise?
Aerobic respiration.
What are the two types of isotonic contractions?
Concentric and eccentric.
Name the connective tissue that surrounds individual muscle fibers.
Endomysium.
Which ion is released from the sarcoplasmic reticulum and is essential for muscle contraction?
Calcium (Ca²⁺)
What role does ATP play in the crossbridge cycle?
It breaks the bond between actin and myosin, allowing the cycle to repeat.
How much ATP does aerobic respiration produce from one glucose molecule?
About 36 ATP.
How does the nervous system increase muscle contraction force?
By recruiting multiple motor units.
*Henneman's size principle*
What does one motor unit consist of?
A motor neuron and all of the muscle fibers it innervates.
During excitation-contraction coupling, which structure in the muscle fiber propagates the action potential deep into the cell?
T-tubules
Describe what happens during the “power stroke” in the crossbridge cycle.
Myosin head pivots, pulling actin toward the sarcomere center, then ADP and Pi are released.
What is physiological fatigue, and how is it different from muscular fatigue?
Physiological fatigue is a feeling of tiredness controlled by the central nervous system, not the muscle itself, while muscular fatigue occurs due to depletion of ATP or buildup of metabolites in muscle cells.
Describe how wave summation leads to tetanus in a muscle fiber.
Wave summation occurs when muscle fibers are stimulated repeatedly without complete relaxation between contractions, resulting in increased tension. If the frequency is high enough, it can lead to a sustained contraction called tetanus, where the muscle reaches maximum tension with no relaxation.