The lymphatic system is involved in the removal of interstitial fluid from tissues, the transport of absorbed fats after digestion, and in protection. Immune cells and substances travel via the lymphatic system, sampling lymph for any potential invaders and mounting an immune response if needed.
There are a lot of systems, so let’s quickly summarize them. The integumentary system covers the entire body, protecting it from damage and regulating body temperature. The scaffold is provided by the skeletal system onto which the muscles act, ultimately facilitating movement. The nervous and endocrine systems are the main regulators, controlling the activity of almost everything via nerves and hormones, respectively.
The respiratory and circulatory systems keep us alive by facilitating breathing and pumping blood around the body, while the digestive systems permits feeding. The resulting wastes are removed and excreted from the body by the urinary system. Last but not least, the reproductive system prevents humanity from going extinct, while the lymphatic system transports lymph and plays a role in the protection from microorganisms.