1. By: Sophie Wilson

2. What is Homeostasis? Homeostasis are the changes in an organism so that it can maintain a stable living environment for itself. Homeostasis is essential for the survival of all living things. Each part of a cell has functions and actions they must carry out to maintain homeostasis.

3. Homeostasis Homeostasis involves a series of mechanisms that can sense and respond to changes in the exterior environment. For survival, the organisms must restore internal environment variables to an acceptable living rate. Two systems that contribute to maintain homeostasis are the nervous system and the endocrine system.

4. Homeostasis Continued… To maintain homeostasis, unicellular organism grow, respond to the changes in its internal and external environment, transform energy as well as reproduce! Homeostasis is needed to maintain balance in chemical and physical conditions.

5. Adaptation Unicellular organisms both include prokaryotes and eukaryotes. Prokaryotes are very adaptable and can survive almost everywhere due to the process of homeostasis. Every organism must obtain certain amounts of different concentrates, food and water so that it may survive. Homeostasis allows organisms to change and use the resources in their environment whether it needs to make rapid or long term changes in its internal environment. However, sometimes the change in the environment can be so dramatized that the organism can not respond to the change so quickly and the entire population can become extinct. Take dinosaurs for example.

6. Working Together To obtain homeostasis, different cells and systems have to function together and communicate with eachother Some cells are specialized to move, others to react to the environment, others to reproduce etc. Just like in our previous explored investigations, cells form tissues, which from organs, which form organ systems which all play a role important to achieve homeostasis. Some organ systems important in homeostasis made up of organs and tissues and cells are the nervous and endocrine system. Everything is given a role using receptors.

7. Nervous System The nervous system helps contribute to homeostasis by: Controls activities within the organism, responding to rapid changes needed in the internal environment due to changes in the external environment. Nervous System also detects changes in the external environment so it can respond to these changes and make a stable living environment.

8. Endocrine System The endocrine system helps maintain homeostasis by: Responds to changes that require duration and time rather than a rapid response. Endocrine System controls the stability of nutrients by adjusting kidney function, controls environments volume, and lastly it controls electrolyte composition throughout the organism

9. What is Involved? Homeostasis consists of: Concentration of nutrients Amount of water, food, salt, and other various food substances. Amount of waste product and what is not needed in the organism (what can be discarded) Blood volume Blood pressure Temperature

10. Why is Homeostasis Needed? Homeostasis is constantly being disrupted by several factors such as: External: Heat, cold, lack of air Pathogens and toxins Internal: Blood Temperature Blood Pressure Amount of water, sugars, salts and other substances Physical and mental stress

11. Homeostasis The organism must be able to: 1. Detect changes in the internal and external environment 2. Respond to these changes to make appropriate adaptations to maintain homeostasis

12. Control Systems Intrinsic Controls Extrinsic Controls Local Controls found in organs Mechanisms found outside the organs. Achieved by nervous and endocrine systems

13. Feed Back! Feed Forward Feed Back Responses made to anticipate change Refers to response after change is made. Two types of feed back are positive and negative

14. Feedback Negative Positive Stimulus is reversed Most feedback systems in the body are negative Uses for helping control the organs and systems that need help to function regularly Stimulus is intensified Seen during child birth: Stretch receptors send signals to the brain and brain releases hormones into blood stream. The uterine contracts and the process ends with the decrease in stretch and birth of child

15. Feedback There are many elements composed in feedback loops such as: 1. Receptor- Structures that monitor and receive impulses indicating change in the internal or external environment. This also consists of your five senses: taste, sight, touch, hear, smell. 2. Control Center- Determines the next action working within the organism. This is your brain. 3. Effector- Receives impulses from the control center and responds to it creating a balanced and stable environment making homeostasis achievable. This consists of muscles and things that make your body move and other characteristics throughout the body or organism.

16. Exploring Receptors When the body is performing an action, many parts of small molecules send out chemical impulses and signals to other cells. To receive these chemical signals a cell must have what is called a receptor which are mostly on the membrane but can sometimes be found in the cytoplasm The chemical signals will work together to create change. For example, a series of impulses are necessary in pumping blood from the heart

17. Receptors include your five senses.

18. Temperature Thermo receptors can detect change in temperature increase in the external and internal environment. The brain will send out impulses to blood vessels and the sweat glands Sweat is released which also causes a decrease in heat restoring normal body temperature

19. Homeostasis temperature control http://www.southtexascolleg e.edu/nilsson/4_gb_lecturen otes_f/4_gb_16_anims_ho_j_ spr2003.html

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