1. Homeostasis

2. Homeostasis  The process of maintaining the body’s internal environment, despite changes in the external environment  This makes sure that the body’s organs and cells are operating at ideal conditions, and thus are most efficient

3. Factors that are regulated  Things regulated include: –Blood pressure –Blood pH –Body temperature –Water levels –Blood glucose levels –Heart rate –Respiratory rate

4. Homeostasis continued  Also called dynamic equilibrium because small changes are constantly occurring  All homeostatic control systems have: –A monitor (sensors that detect imbalance) –Coordinating center (relays information) –Receptor (works to restore balance)  These systems of control are called feedback loops

5. Negative Feedback Loop  Mechanisms that work to restore the system to normal levels  Negative feedback ensures that small changes do not get too large  Ex. When body temperature rises, you begin to sweat in order to lower temperature  The more common type of feedback loop

6. Positive Feedback Loop  When the change in a system causes the system to amplify the change  Less common  Ex. During childbirth, as the baby moves towards the cervix, more oxytocin is released, which increases contractions.

7. Thermoregulation  The maintaining of body temperature  Ectotherms (fish, amphibians, reptiles) depend on the air to regulate body temperature  Endotherms (mammals and birds) maintain a constant body temperature via internal systems  Normal body temperature in humans = 37°C  Hypothalamus acts as the ‘thermostat’