• Respiratory system

1. The respiratory system transports oxygen and depends on the blood circulatory system to deliver oxygen to the whole body.
2. The respiratory system also relies on the blood circulatory system to help get rid of carbon dioxide from the body.

• Skeletal system

1. The blood circulatory system transports oxygen and nutrients to the skeletal system to help the growth of bones
2. The skeletal system, in turn, protects the body & the organs involved in respiration & blood circulation such as the lungs & heart

• Digestive system

1. The blood circulatory system transports oxygen to the digestive system
2. The digestive system supplies nutrients to organs such as the heart in order to function properly

• The systems in the human body cannot function independently
• If one system fails to function, the other system will also be affected

Digestive system and respiratory system

• When food gets stuck in a person's throat, their digestive system is disrupted at the esophagus.
• Food trapped in the esophagus will block air from entering the trachea and will cause the respiratory system to be disrupted due to difficulty in breathing.

Skeletal system and circulatory system

• Broken bones affect the blood circulatory system
• The broken bone body part will swell because the blood flow in the blood circulatory system is disrupted