FEEDBACK MECHANISMS & HOMEOSTASIS

HOMEOSTASIS Maintaining the internal environment within a stable range given factors that influence the external environment Homeostasis controls many aspects of the internal environment, for example: Body temperature Blood concentrations of: glucose, hormones, carbon dioxide and ions Oxygen levels Blood pH Blood pressure Solute concentration (Water balance)

FEEDBACK MECHANISMS Maintain homeostasis by detecting and responding to a stimulus A non-biology example:

NEGATIVE FEEDBACK Reduces the size of the stimulus to restore homeostasis

NEGATIVE FEEDBACK: HUMANS

NEGATIVE FEEDBACK: PLANTS

POSITIVE FEEDBACK Response increases the original stimulus to restore homeostasis Rarely used Only normal when there is a definite end point Childbirth Blood clotting