Muscle contractions

"What is the first step in the sliding filament mechanism of muscle contraction?"

"Action potential moves down T tubules (T tubes)."

"What is released from the sarcoplasmic reticulum in response to the action potential?"

"Calcium ions (Ca²⁺).

"What effect do calcium ions have on tropomyosin?"

"They cause tropomyosin molecules to move away from the binding sites on actin."

"What happens after tropomyosin moves away from the binding sites?"

"Myosin heads can bind to the active sites on actin."

"What is the ""power stroke"" in muscle contraction?"

"When the myosin head pulls the actin filament closer to the m line

"What molecule is released during the power stroke?"

ADP

"What molecule binds to the myosin head to cause detachment from actin?"

ATP

"What happens when ATP binds to the myosin head?"

"It causes the myosin head to detach from actin through hydrolysis (forming ADP + Pᵢ)."

"How does the myosin head return to its original position after detaching?"

"Using energy from ATP hydrolysis

"What happens during muscle relaxation regarding calcium ions?"

"Calcium ions are actively transported back into the sarcoplasmic reticulum."

"What role does tropomyosin play in muscle relaxation?"

"It moves back to block the binding sites on actin."

"How is ATP supplied to muscles under anaerobic conditions?"

"Through phosphocreatine and partly by glycolysis."

"What evidence supports the sliding filament theory?"

The A band stays the same length I band and h zone shortebn

What types of pairs do muscles come in

Antagonistic