1. The Endocrine System and Homeostasis
9 Biology

2. The Endocrine System: Includes glands and organs
Releases hormones into the bloodstream
Regulates cell behavior
Maintains homeostasis in human systems

3. Hormones Endocrine glands release hormones into bloodstream
Hormones are chemical messengers that have a target organ
Hormones only affect behavior of target organ

4. Positive Feedback Loops:
Homeostasis is maintained by using the endocrine system (pituitary gland) and hormones (oxytocin)
Ex. Before birth, baby pushes on cervix, stretching it, stretching causes oxytocin to be released which causes uterus to contract, causing the baby to push against cervix

5. Negative Feedback Loops:
Change is detected, so mechanisms adjust system back to ideal conditions
Ex. Rise in blood sugar triggers insulin release cells take up glucose blood sugar lowered back to original level.

6. Feedback Loops: Positive Negative
Initial change brings about additional change
Original stimulus is enhanced.
Causes a continuation
Original balance is constantly regulated
Once original balance is restored, response is stopped.
Causes a cessation

7. Hormone Chart Hormone: Synthesized in: Function: Insulin Oxytocin
Testosterone
Estrogen