Final answer:
The hydrochloric acid in the stomach destroying pathogens and the dilation of blood vessels in response to histamine are examples of the immune system's relationship with other body systems, as is the transmission of antibodies through breastfeeding.
Step-by-step explanation:
The relationship between the immune system and another system of the body is exemplified by the destruction of a pathogen by the hydrochloric acid in the stomach. This shows how the digestive system (specifically, the stomach) plays a role in the innate immune response by using hydrochloric acid as a barrier to destroy pathogens that enter the gastrointestinal tract.
Additionally, the dilation of blood vessels in response to histamine demonstrates the interaction between the immune system and the circulatory system, where histamine—a compound released by cells in response to injury and in allergic and inflammatory reactions—causes blood vessels to expand to allow more immune cells to reach the site of an infection or injury. Lastly, the introduction of antibodies through breastfeeding is an example of how the immune system of the mother interacts with the digestive system of the infant, providing passive immunity to the infant through breast milk.