As well as having a great eccet on waer intake in the cell, turgor pressure can also mediate rapid movements in the cell. For example, there is one plant where if it is touched, all of the leaves very rapidly close up and shrink back. This is caused by changes in turgor pressure. When the leaf is normal wih nothing touching it, the flexor cells and the extensor cells are both extended and turgid. But, after the plant has been touched, the flexor cells become stretched and the extensor ccells become flaccid. In the turgid state, the cell is completely filled with water. But as the cell is touched and begins to shrink, H+ ions enter the cell, while Cl-, K+, and some water leave the cell. This leaves the cell in its flaccid state, where there is still some water, but it is in pockets, and the overall size of the cell is smaller, as previously described. There is low turgor pressure in this state. Then, after a while, the cells begin to sweel to their turgid state, and H2-, K+, and Cl- enter the cell, while H+ leaves the cell. This allows the cell to completely filll up with water so that there is high turgor pressure in the cell.
Turgor pressure is also very important in sunflower movement. Sunflowers move in response to the sunn and follow it though the day. At night, the sunflowers still move to face the east even though there is no sunlight, so that they can be in the optimal position when the sun rises. This is due to their intrinsic circadian rhythms. However, this movemen of following the sun is due to changes in turgor pressure in the cells at the base of the moving organ in the sunflower.
The primary cell wall contains cellulose microfibrils that are a part of a polysaccharide matrix. The matrix has pectins, which are polysaccharides that can create a hydrated gel phase, and hemicellulose, which are flexible polysaccharides that like cellulose. The primary cell wall is about 25% cellulose, 25% hemicellulose, 35% pectin, and 1-8% structural proteins, but these numbers can be highly variable depending on the tested structure. These are the parts in the priamry cell wall that are involved in expanding the cell.