If you're seeing this message, it means we're having trouble loading external resources on our website.
If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.
Main content
Unit 7: Foundation 3: Organ systems
About this unit
Nervous that your knowledge of organ systems is Skeletal? Don't be! After you Muscle your way through this unit on organ systems, you'll be able to discuss how specialized tissues are arranged into organs, and how different organ systems work together to maintain homeostasis, enable reproduction, and respond to environmental threats such as pathogens.