Answer and 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, tropomyosin is obstructing binding sites for myosin on the thin filament. 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 released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. 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.
The endoplasmic reticulum, or ER, and Golgi apparatus, prepare molecules, including proteins, hormones and lipids, and package them in vesicles for transport. Rough ER is studded with ribosomes that synthesize proteins, while the smooth ER manufactures lipids.
Um lets see so first coold air comes pushing awah heat to another area. i tihnk
Answer:
C) It has a long preganglionic fibers
Explanation:
Peripheral nervous system (PNS) is the nervous system that contains nerves and ganglia outside the central nervous system (CNS). PNS is divided into:
- somatic (voluntary) nervous system-controls the movements of the skeletal muscles
- autonomic (involuntary) nervous system-controls the smooth muscles and glands and thus it is the regulator of the major body functions. It is subdivided into tree groups:
- sympathetic ("fight and flight") system-responsible for stressful and active situations (but also in normal conditions);contains short preganglionic fibers and long postganglionic fibers.
- parasympathetic ("rest and digest") system-opposite to sympathetic, responsible for the maintenance of body's activities at rest.
- enteric nervous system-controls the function of the gastrointestinal tract.
