Answer:
The correct answer is 3: "<em>High levels of Ca2+ are expected to be found </em><em>within the sarcoplasmic reticulum</em>".
Explanation:
Muscular contraction is a highly regulated process that depends on free calcium concentration in the cytoplasm. Amounts of cytoplasmic calcium are regulated by <u>sarcoplasmic reticulum</u> that functions as a storage of the ion.
When a nerve impulse reaches the membrane of a muscle fiber, through acetylcholine release, the membrane depolarizes producing the entrance of calcium from <u>extracellular space</u>. The impulse is transmitted along the membrane to the sarcoplasmic reticulum, from where calcium is released. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. The calcium channel in the sarcoplasmic reticulum controls the ion release, that activates and regulates muscle contraction, by increasing its cytoplasmic levels. When <em>calcium binds to the troponin C</em>, <em>the troponin T alters the tropomyosin by moving it and then unblocks the binding sites,</em> making possible the formation of <em>cross-bridges between actin and myosin filaments.</em> When myosin binds to the uncovered actin-binding sites, ATP is transformed into ADP and inorganic phosphate.
Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
The ability of body systems to increase their function, given the need to adapt, is known as the <u>physiologic reserve.</u>
Explanation:
The ability of body systems to increase their function if the need to adapt arises is known as a physiological reserve. Frequently, this term is used to refer to the operating limits of a particular physiological system when under stress. When this stress exceeds the ability of a particular organ or system to compensate for it, organ failure occurs. Adaptation achieves its highest efficiency when changes are generated gradually/progressively rather than abruptly. In aging, this reserve is diminished and therefore the ability of the organs to adapt to stress is lower, that is, the ability to adapt is reduced in extreme ages.
The cell because they are moving from high to low concentration
Answer:
35 Phyla
Explanation:
This is somewhat debated but the correct answer is 35 as this is the most agreed upon number and is closest to the alternate numbers
