The respiratory system brings oxygen into the lungs when you breathe. The digestive system breaks food down into nutrients such as glucose. Now the circulatory system enters the picture. It transports glucose and other nutrients from the digestive system to the cells. Integumentary System. (The skin, hair, and nails form the body's outer covering, or integument.) Muscular System Skeletal System Circulatory System Nervous System Respiratory System Hope this helps!:)
