I would think all of them?
It is important because each system does a cetain job for that organ.
The brain is the most important organ of the nervous system. The spinal cord and the brain are the main parts of the nervous system but the spinal cord is not considered to be an organ.
okem
lungs
The lungs.
the important organ in the respiratory system would be the lungs. There are many other organs that are just as important as the lungs such as diaphram, capillaries, etc. but the lungs are considered to be the "stars"
Because it's one of your "Organ System".
skin!
The Kidneys
The spinal cord.
YES it is an organ system?
Skin is an organ, not an organ system. It is part of the integumentary system.