Lysosomes digest foreign materials and food, explains a Georgia State University website. These organelles contain digestive enzymes. Lysosomes keep cells clean and recycle materials. A cell contains many lysosomes. The lysosome has a plasma membrane surrounding it, which protects the rest of the cell from the destructive enzymes contained within the organelle.
Endocytosis is the process by which a lysosome digests substances. A lysosome has about 40 different enzymes used for digestion. These enzymes are made in the endoplasmic reticulum and packaged in the Golgi apparatus. Lysosomes usually originate from the pinching off of the Golgi apparatus, but they can also arise from endosomes.
After substances, such as cellular wastes, old organelles, fats, carbohydrates and proteins, are broken down in the lysosomes, the products are then released back into the cytoplasm to become the raw materials for the making of new substances and cellular structures. When a lysosome digests food, it meets up with a food vacuole and fuses with it, releasing its digesting enzymes into the vacuole. The process of digesting cellular components is autophagy; the process of engulfing and digesting food particles or foreign substances is called phagocytosis.
Although lysosomes dwell within all animal cells, many of them reside within white blood cells. Because white blood cells encounter foreign invaders and pathogens, they must be able to render the invaders harmless by digesting them within their lysosomes.