Matching Pairs Tissues, Organs, and Body SystemsOnline version Review the tissue, organ, and body systems. by Janelle Ruiz 1 Digestive System 2 Muscular System 3 Circulatory System 4 Nervous System 5 Epithelial Tissue 6 Respiratory System 7 Connective Tissue Lines organs and protects inside of body from outside world Supports organs and joins tissue Responsible for gas exchange (oxygen- carbon dioxide) with the outside environment Brain, spinal column, axons Heart, veins, capillaries