1. F. Necessary Life Functions - Our organ systems work together to maintain the following functions:

2. 1. Maintaining Boundaries a. starting at the cellular level our bodies have distinct boundaries (membranes) separating the inside from the outside b. membranes allow entry in of needed substances and prevent the entry of harmful substances c. most responsible is the integumentary system

3. 2. Movement a. Movement occurs in the muscular and skeletal systems b. Movement occurs in many organ systems as well such as the digestive

4. 3. Responsiveness a. The ability of your organ system to sense a change in the environment and then react b. The nervous system is most responsible for this function

5. 4. Digestion a. The digestive system is the most responsible b. The cardiovascular system provides transportation for the nutrients

6. 5. Metabolism a. All chemical reactions (break down, build up) b. These reactions are regulated by hormones which are secreted by the endocrine system c. Metabolism depends on the digestive system to make nutrients available

7. 6. Excretion a. The process of removing waste b. The digestive system removes feces c. The urinary system removes urine

8. 7. Reproduction a. The production of offspring at the cellular level and at the organism level b.cells divide for growth and repair c. The reproductive and endocrine systems are responsible at the organism level

9. 8.Growth a. An increase in size due to an increase in the number of cells b. Many organ systems are involved

10. G. Homeostasis 1. the body’s ability to maintain a stable and balanced internal environment 2. its loss results in illness or disease 3. homeostatic control center is composed of : a. Receptor – responds to change b. Control center – brain/assesses change c. Effector – produces a response

11. d. Metabolism depends on the respiratory system to make oxygen available. e. Metabolism depends on the cardiovascular system to distribute these substances

12. 4. negative feedback systems – this system is used to reduce or stop the initial stimulus