Through which physiological system would poison ivy have an effect on workers?

Poison ivy primarily affects the immune system. When a person comes into contact with poison ivy, they can develop an allergic reaction due to the urushiol oil found in the plant. This oil can trigger the immune system to respond vigorously, causing symptoms such as itching, redness, and swelling on the skin, commonly known as contact dermatitis.

The physiological response involves the immune system recognizing urushiol as a harmful substance, leading to an inflammatory reaction. This reaction not only manifests through visible skin changes but also involves the activation of immune cells to respond to the perceived threat. The immune system plays a crucial role in protecting the body from environmental toxins, including allergens like the one found in poison ivy, highlighting its significance in this context.

The other systems mentioned in the options play different roles in bodily functions and responses. The nervous system is primarily involved in processing sensory information and coordinating bodily responses; the respiratory system is responsible for gas exchange and not specifically involved in allergic reactions to allergens like poison ivy; and the metabolic system is focused on the biochemical processes needed for energy conversion and sustenance, which are not directly impacted by contact with poison ivy.