Animals with horns shed them every year. The gastrocnemius is the muscle that extends the forearm. Arteries carry blood under high pressure. The walls of capillaries are only one cell thick. The lifespan of a red blood cell is about 120 days.
Impulses travel through nerves because of ions.
Latitude describes locations north or south of the equator. The highest elevation in Oklahoma is in the southeast corner of the state. Estuaries are where rivers meet the sea and fresh water mixes with salt water. Intraspecies competition occurs between organisms of the same species. The population in a given area at a given time is known as carrying capacity.