Overview Rash from poison ivy. Many people develop an itchy rash that causes lines or streaks that look like this. Poison ivy, oak and sumac: Overview Many people get a rash from poison ivy, poison oak, and poison sumac. This rash is caused by an oil found in the plants. This oil is called urushiol (you-ROO-shee-all).
Cells in heart muscle process a lot of energy, so they have a large number of mitochondrion, the part of the cells where energy is made. Like all living things, cells die. The number of cells that an adult male loses per minute is roughly 96 million.
For higher-order species the length of the cell cycle determines how long it takes to replace damaged cells. The duration of the cell cycle varies from organism to organism and from cell to cell. Certain fly embryos sport cell cycles that last only 8 minutes per cycle! Some mammals take much longer than that--up to a year in certain liver cells. Generally, however, for fast-dividing mammalian cells, the length of the cycle is approximately 24 hours.