Which of the following is NOT a function of the muscular system?

Correct Answer: D

Rationale: The muscular system is responsible for movement, maintaining posture, and generating heat. Regulating blood sugar levels is not a function of the muscular system. This function is primarily carried out by the endocrine system, specifically the pancreas and its production of insulin and glucagon. Choices A, B, and C are all correct functions of the muscular system as they involve the contraction and relaxation of muscles to produce movement, support the body's structure, and generate heat as a byproduct of muscle activity.

Correct Answer: B

Rationale: Acetylcholine is the neurotransmitter responsible for muscle movement. It is released from motor neurons at the neuromuscular junction and binds to receptors on muscle fibers, initiating muscle contraction. Dopamine, serotonin, and GABA serve different functions in the brain and body, such as regulating mood, sleep, and inhibitory signaling, respectively. Therefore, choices A, C, and D are incorrect in the context of muscle movement.

Correct Answer: C

Rationale: The main target organ for insulin is muscles. Insulin plays a crucial role in regulating glucose metabolism by promoting the uptake of glucose into muscle cells. This glucose can then be utilized for energy production or stored for later use. Therefore, muscles are the primary site where insulin exerts its effects on glucose uptake and utilization. The liver primarily responds to insulin by regulating glucose storage and release, but the main target for insulin-mediated glucose uptake is muscles. Kidneys are not a target organ for insulin action in glucose metabolism. The brain does not heavily rely on insulin for glucose uptake as it primarily uses glucose independently of insulin for energy production.

Correct Answer: B

Rationale: Antagonist muscles are pairs of muscles that work in opposition to each other, producing opposing movements. When one muscle contracts, the other relaxes to allow the movement to occur smoothly. Synergists are muscles that work together to create a movement, not in opposition. Agonists are muscles primarily responsible for producing a specific movement, not opposing each other. Fixators are muscles that stabilize joints to allow other movements to take place, providing a stable base for muscle actions but do not produce opposing movements.

Correct Answer: B

Rationale: Regeneration is the correct answer. It is the process by which damaged muscle tissue repairs and rebuilds itself. New muscle cells are formed during regeneration to replace the damaged ones, allowing the muscle to heal and regain its function. Degeneration refers to tissue breakdown, hyperplasia is the increase in the number of cells in an organ or tissue, and metaplasia is the transformation of one type of tissue into another.