Which is NOT a function of muscles?
**Core Concept**
Muscles are dynamic tissues that perform several critical functions in the human body. They enable movement, maintain posture, regulate body temperature, and facilitate the transmission of nerve impulses through the action potential. Muscles also play a role in the storage and release of various substances, such as glycogen and lactate.
**Why the Correct Answer is Right**
The correct answer will be the option that does not align with any of the known functions of muscles. Muscles are primarily responsible for movement and locomotion through the contraction and relaxation of muscle fibers. They also maintain posture by stabilizing joints and bones. Additionally, muscles regulate body temperature through shivering and vasodilation/vasoconstriction. However, the storage and release of substances is primarily a function of the liver, pancreas, and adipose tissue, rather than muscles.
**Why Each Wrong Option is Incorrect**
**Option A:** Movement is a primary function of muscles, achieved through the contraction and relaxation of muscle fibers.
**Option B:** Posture is maintained by muscles, which stabilize joints and bones to prevent excessive movement.
**Option C:** Temperature regulation is also a function of muscles, particularly through shivering and vasodilation/vasoconstriction.
**Clinical Pearl / High-Yield Fact**
Muscles are responsible for approximately 30% of the body's resting energy expenditure, making them a significant contributor to overall energy metabolism.
**Correct Answer: D. Storage and release of substances.**