We eat food for nutrients and energy. our digestive system does the work to physically and chemically digest or decompose the food we eat. but how do the nutrients and energy-rich molecules get to our cells? what systems and organs are involved? a) the digestive and cardiovascular systems are involved. digestion takes place in the intestines and nutrients and carbohydrates are absorbed into the blood there for distribution to all cells. eliminate b) the digestive and excretory systems are involved. digestion takes place in the intestines and nutrients and carbohydrates are absorbed into the blood stream; wastes leave the body via the excretory system. c) the digestive, cardiovascular and skeletal systems are involved. digestion is completed in the small intestines. sugars, fats and amino acids are absorbed into the bloodstream and nutrients into the bone marrow of the skeletal system. d) the digestive, cardiovascular and lymphatic systems are involved. digestion is completed in the small intestines. nutrients, sugars and amino acids are absorbed into the bloodstream and glycerol and fatty acids into the lymphatic system.