Lysosomes function much in the same way as the digestive system, in that they contain digestive enzymes that break down biological molecules, including carbohydrates, proteins, nucleic acids and lipids. They also destroy dead organelles inside the cell, allowing them to be replaced with more effective ones, a process known as autophagy.
Lysosomes release enzymes outside the cell to destroy pathogens and remove cell debris through a process known as phagocytosis. They digest materials ingested from the extracellular environment, a process known as heterophagy. Heterophagocytosis is the uptake of materials outside the cell via phagocytosis. Examples include removal of apoptotic cells by macrophages and intake and digestion of bacteria by neutrophils.
Lysosomes completely destroy those cells that have died, a process known as autolysis, more commonly referred to as self-digestion. They also recycle complex products formed through the process of biosynthesis. In general, lysosomes carry out the digestion of food particles. The digestive enzymes contained in lysosomes are harsh. If released from their host cell, they are powerful enough to destroy it. However, normal cells remain within the lysosomes' membranes to protect the cells from the digestive enzymes.
A lysosome defect can lead to diseases such as acid maltase deficiency, Tay-Sachs disease and Pompe disease. These conditions are referred to as lysosomal storage disorders.