Question: what are the major organs of the body system?
Answer: Circulatory system: heart, blood, blood vessels, and lymphatics.
Digestive system: esophagus, stomach, small intestine, and colon.
Endocrine system: pituitary, thyroid, ovaries, and testes.
Immune system: organs (including lymphatics and spleen), special. ... 
Integumentary system: skin, hair, nails, and sweat glands.