Which system maintains posture and produces body heat through muscle activity?

The Muscular System is essential for maintaining posture and generating body heat through muscle activity. Posture is supported by the continuous contraction of various muscles, which allows the body to stay upright and aligned. When these muscles contract, they also produce heat as a byproduct of metabolic processes involved in muscular activity. This thermogenic function helps regulate body temperature, especially during physical exertion.

The other systems listed play important roles in the body, but they do not directly contribute to posture maintenance and heat production to the same extent as the Muscular System. The Integumentary System involves skin functions such as protection and temperature regulation but does not produce heat through muscle activity. The Endocrine System is responsible for hormone regulation, enabling various bodily functions but is not directly involved in physical posture. The Skeletal System provides structural support and aids in movement but relies on muscles to maintain posture and generate heat.