Regulation is the life process by which organisms and cells respond to our constantly changing internal and external environment. This is important because an upset in homeostasis in any one of an organism's systems might result in an imbalance in the organism's homeostasis. In humans, regulation consists of the endocrine and nervous systems. The endocrine system is made up of many organs that produce hormones into the bloodstream. The nervous system carries messages in the form or nerve impulses throughout the body. Hormones and nerve impulses can bring about changes in the organism in response to the environment. Regulation coordinates body activities and adjusts them when internal or external environmental changes occur which helps maintain homeostasis within the body.
Mitosis and meiosis are both processes of cell division. Mitosis is the process by which the nucleus of a cell divides to create two new nuclei, each containing an identical copy of DNA.
Mitotic cell division occurs in all body cells except for sex cells. Meiosis is the process of cell division that results in gametes in animals or spores in plants with half the number of chromosomes as the parent cell. Meiosis is a sexual process opposed to mitosis which is an asexual process. While in mitosis the cell divides once, in meiosis the cell divides twice, yielding four daughter cells. Cells produced by mitosis are diploid, and cells produces by meiosis are monoploid. Crossing-over may occur in meiosis, but not mitosis. In both processes, the chromosomes replicate only once.