You Isolate Some Muscle Fibers to Examine What Regulates Muscle

question 16

Essay

You isolate some muscle fibers to examine what regulates muscle contraction.When you bathe the muscle fibers in a solution containing ATP and Ca²⁺, you see muscle contraction (experiment 3 in Table 17-22).Ca²⁺ is necessary, as solutions containing ATP alone or nothing do not stimulate contraction and thus the muscle remains in a relaxed state (experiments 1 and 2 in Table 17-22).From what you know about the mechanism of muscle contraction, fill in your predictions of whether the muscle will be contracted or relaxed for experiments 4, 5, and 6.Explain your answers. $\begin{array}{llcc} \text { Experiment } & \\ \text { number } & \text { added to muscle fibers}& \text {muscle state}\\\hline 1& \text { nothing } & \text {relaxed}\\\hline 2& \text { ATP } & \text {relaxed}\\\hline3& \text { ATP and \( \mathrm{Ca}^{2+} \) } & \text {contracted}\\ \hline4& \text { ATP, \( \mathrm{Ca}^{2+} \), and a drug that inhibits troponin from binding \( \mathrm{Ca}^{2+} \)} &\\\hline 5&\text { ATP and a drug that inhibits binding of tropomyosin to actin } &\\\hline 6&\text { a nonhydrolvzable analog of ATP } &\end{array}$

Table 17-22
Extra credit: In what state would the muscle be if you added Ca²⁺ but no ATP?

---

Definitions:

Legal Presumption

A rule that requires a court or tribunal to assume a fact is true until it is disproven by evidence to the contrary.

Commercial Arrangements

Agreements or transactions between businesses or entities that are commercial in nature, often involving the exchange of goods or services.

Mental Incapacity

A state where an individual is unable to understand the nature and consequences of their actions, affecting their ability to enter legal agreements or make decisions.

Essential Terms

Fundamental conditions or clauses in a contract that are necessary to the performance of that contract.