Answer:
A frogs heart has 3 chambers. Two atria and a single ventricle.
Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
The bicondylar angle positions the center of mass above the base of support during the single-support phase of bipedal locomotion.
A. True
Explanation:
The bicondylar angle is the functional angle between the diaphysis of the femur, perpendicular to the intercondylar plane. Very unique to humans, this angle places the knee and the foot under the body's center of gravity during a single support phase of locomotion or gait. With hip joints set lateral to the body's midline, the bicondylar angle aligns the lower limb with the center of gravity, thereby facilitating human movement.
Answer:
Earthquakes and Volcano activity
Explanation:
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