1. Maintain yourself!

2. What is it? HOMEOSTASIS- this means a state of equilibrium homeo--same stasis--standing still A. The maintenance of a stable internal environment Maintains conditions necessary to support life A. Homeostasis is the regulation and maintenance of the internal environment of the body

3. HOMEOSTASIS It works in all levels of the body: Cellular Tissues Organs Organ Systems

4. Tell your table buddy what happens if your homeostasis goes out of normal ranges and the body cant bring it back.

5. HOMEOSTASIS There are 100’s of monitored events in the body that must be maintained in order to function efficiently A. these conditions are maintained by feedback systems There are negative and positive feedback systems

6. HOMEOSTASIS NEGATIVE FEEDBACK- this tells the body to stop what it is doing when it goes outside of the acceptable range.

7. NEGATIVE FEEDBACK EXAMPLES EXAMPLE: when you are asked to give a report in front of the class. You are sometimes stressed! Your heart starts beating faster and your blood pressure goes up Little sensors called baroreceptors sense the change, and the negative feedback systems will stimulate the heart to decrease the force and frequency of the heartbeat. Once this kicks in, the body restores the normal blood pressure

8. POSITIVE FEEDBACK POSITIVE FEEDBACK- this tells the body to continue doing what it is doing

9. POSITIVE FEEDBACK EXAMPLE OF POSITIVE FEEDBACK: when contractions begin to push the baby into the birth canal, the pressure of the baby stimulates increased strength of contractions The force of the contractions continue until the pressure of the baby in the birth canal is decreased

10. Stretch receptors in walls of uterus send signals to the brain Stretch receptors in walls of uterus send signals to the brain Brain induces release of hormone (oxytocin) into bloodstream Brain induces release of hormone (oxytocin) into bloodstream Uterine smooth muscle contracts more forcefully Uterine smooth muscle contracts more forcefully More stretch, more hormone, more contraction etc. More stretch, more hormone, more contraction etc. Cycle ends with birth of the baby & decrease in stretch Cycle ends with birth of the baby & decrease in stretch Positive Feedback during Childbirth

11. Negative feedback loop Negative feedback loop original stimulus reversed original stimulus reversed most feedback systems in the body are negative most feedback systems in the body are negative used for conditions that need frequent adjustment used for conditions that need frequent adjustment Positive feedback loop Positive feedback loop original stimulus intensified original stimulus intensified seen during normal childbirth seen during normal childbirth Feedback Loops: Types

12. Negative feed back loop consists of: Negative feed back loop consists of: Receptor - structures that monitor a controlled condition and detect changes Receptor - structures that monitor a controlled condition and detect changes Control center - determines next action Control center - determines next action Effector Effector receives directions from the control center receives directions from the control center produces a response that restores the controlled condition produces a response that restores the controlled condition

13. Homeostasis – Negative Feedback Loop

14. OTHER METHODS OF HOMEOSTASIS ENDOCRINE AND NERVOUS SYSTEMS- These work together to maintain homeostasis, and sometimes they work independently Endocrine system delivers chemical messages Nervous system delivers electrical messages

15. ENDOCRINE AND NERVOUS Both of these systems are responsible for blood sugar levels, electrolyte balance, blood pressure, internal temperature, skin temperature, blood O2 levels

16. BODY TEMPS There are 2 ways of gaining heat in our bodies 1. internal heat production: muscle contraction other metabolic activities like digestion 2. environmental changes- outside temperature

17. Heat loss There are 4 different ways to loose heat from your body: 1. Evaporation- this is heat loss from converting water from a liquid to a vapor 2. Conduction- this is heat loss through direct contact with something (like water) 3. Convection- the process of conduction where one object is in motion 4. Radiation- loss of heat to the environment due to the temperature gradient

18. Cool your body 1. sweating 2. Blood vessel dilation

19. Tell your table buddy why wearing heavy clothes in summer heat is a bad idea.

20. Okay, if I’m cold, how do I warm up? Shivering- this is involuntary Constriction of dermal blood vessels

21. Homeostasis is continually being disrupted by Homeostasis is continually being disrupted by External stimuli External stimuli heat, cold, lack of oxygen, pathogens, toxins heat, cold, lack of oxygen, pathogens, toxins Internal stimuli Internal stimuli Body temperature Body temperature Blood pressure Blood pressure Concentration of water, glucose, salts, oxygen, etc. Concentration of water, glucose, salts, oxygen, etc. Physical and psychological distresses Physical and psychological distresses Disruptions can be mild to severe Disruptions can be mild to severe If homeostasis is not maintained, death may result If homeostasis is not maintained, death may result

22. Control of Homeostasis

23. tell your table buddy what is negative feedback and positive feedback.