1.2. Homeostasis http://www.ck12.org
FIGURE 1.
Feedback Regulation.Positive Feedback
Some processes in the body are regulated by positive feedback.Positive feedbackis when a response to an event
increases the likelihood of the event to continue. An example of positive feedback is milk production in nursing
mothers. As the baby drinks her mother’s milk, thehormoneprolactin, a chemical signal, is released. The more the
baby suckles, the more prolactin is released, which causes more milk to be produced.
Vocabulary
- homeostasis: Ability to keep a stable internal environment; the ability of the body to maintain a stable internal
environment despite a changing environment. - hormone: Chemical messenger molecule.
- negative feedback: Response to a stimulus that keeps a variable close to a set value.
- positive feedback: Response to an event increases the likelihood of the event to continue.
Summary
- Homeostasis is the ability of the body to maintain a stable internal environment despite a changing external
environment. - Homeostasis is maintained primarily through negative feedback, when a response to a stimulus keeps a
variable close to a set value.
Practice
Use the resources below to answer the questions that follow.
- Homeostasisat http://www.phys.unsw.edu.au/biosnippets/