Which system controls the body's responses to internal and external changes?

Which system controls the body's responses to internal and external changes?

• A. Nervous System
• B. Immune System
• C. Digestive System
• D. Respiratory System

Answer: (A)

The nervous system coordinates the body's responses to changes both inside and outside. It uses sensors all over the body to notice things like temperature, pain, light, and muscle position, and it sends messages through nerves to the brain and spinal cord. The brain then sends rapid signals back out to muscles and glands, so you can react quickly or adjust what's happening inside your body. This system lets you blink when something comes toward your eye, pull your hand away from something hot, or change your heart rate and sweating to keep your body balanced. Other systems have important jobs too—like defending against germs (immune), breaking down food (digestive), or moving air in and out of the lungs (respiratory)—but they don’t coordinate fast, whole-body responses the way the nervous system does. So the nervous system is the one that controls the body's responses to internal and external changes.

The nervous system coordinates the body's responses to changes both inside and outside. It uses sensors all over the body to notice things like temperature, pain, light, and muscle position, and it sends messages through nerves to the brain and spinal cord. The brain then sends rapid signals back out to muscles and glands, so you can react quickly or adjust what's happening inside your body. This system lets you blink when something comes toward your eye, pull your hand away from something hot, or change your heart rate and sweating to keep your body balanced. Other systems have important jobs too—like defending against germs (immune), breaking down food (digestive), or moving air in and out of the lungs (respiratory)—but they don’t coordinate fast, whole-body responses the way the nervous system does. So the nervous system is the one that controls the body's responses to internal and external changes.