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:
their are two electric and body cells which is body building blocks of life which
<h3>Each secondary spermatocyte completes the second meiotic division without the replication of DNA and produces 2 spermatids each containing 23 chromosomes. Spermatids undergo morphologic alteration (spermiogenesis) to become mature spermatozoa.</h3>
Answer:
Change in the vascular system.
Explanation:
High blood pressure occurs when the arteries in the human body system become rigid thereby making the blood pressure rise.
The cause for this situation particularly in older people is the changes in the vascular system or circulatory system.
This is said to be vasoconstriction which lowers the flow of blood in the circulatory system, thereby causing high blood pressure
Hence, since Mr. Ackah is a retired teacher, it is believed that he is an old man susceptible to changes in the vascular system or vasoconstriction.
