person has a stomach – a convenient organ where food is digested, splits into simple compounds which are then absorbed by the body and are used for its needs. However, tiny organisms — protozoa and sponges — have no stomach. Its role is played by the phagosome, also called the digestive vacuol—a vesicle surrounded by a membrane. It is formed around a solid particle or cell, which the body decided to use in food. There is a digestive vacuole and around a dipped drop of liquid. The phagosome fuses with the lysosome, enzymes are activated and the digestion process begins, which lasts about an hour. During digestion, the environment inside the phagosome changes from acidic to alkaline. Once all nutrients have been extracted, undigested food remains are excreted from the body through the powder or cell membrane.
Digesting of solid food is called phagocytosis, liquid — pinocytosis.
Many protists and some sponges have a contractile vacuol.$ The main function of this organoid is regulation of osmotic pressure. Through the cell membrane, water enters the cell of the sponge or protozoa, and periodically with an equal amount of time the fluid is excreted outward using a contractile vacuole which, sprawling to of a certain point, then begins to contract with the help of the elastic beams available therein.
There is a hypothesis that the contractile vacuole takes part in cellular respiration as well.
Vacuol in plant cell
The plants also have vacuoles. In a young cell, there are usually several small sized pieces present, however as the cell grows, they grow larger and fuse into one large vacuole, which is capable of occupying 70 -80% of the whole cells. Vegetable vacuole contains cellular juice, which includes minerals, sugars and organic matter. The main function of this organoid is to maintain the turgor. Also, plant vacuoles are involved in water-salt metabolism, the cleavage and absorption of nutrients and the disposal of compounds that can harm the cell. Green parts of plants not covered with wood retain their shape due to a strong cell wall and vacuoles that keep the cell shape unchanged and do not allow deformation.