Cytoplasm is the jelly-like substance filling a cell, enclosed by the plasma membrane, and excluding the nucleus in eukaryotic cells. It is composed of a complex mixture of materials, including cytosol (the liquid portion), which primarily consists of water, dissolved salts, and various organic molecules. The cytoplasm is responsible for maintaining the cell's structural integrity and providing the medium for nearly all essential metabolic reactions. Within it suspended are numerous organelles, such as mitochondria and endoplasmic reticulum, which perform specialized functions like generating energy (ATP), protein synthesis, and detoxification. The internal environment provided by the cytoplasm is crucial for cellular homeostasis and the overall viability of the biological entity.