Endocrine: A gland that releases its secretions (hormones) directly into the blood, which carries these secretions to other areas of the body.

Key Terms

Ectotherm: An animal whose body temperature is determined mainly by the temperature of its environment.

Endotherm: an animal whose body temperature is regulated, at least in part, using heat created within its body.

Homeostasis: Relatively constant internal physical and chemical conditions that organisms maintain.