1. Warm-Up!!! 4/23 Cell Cycle! Label #s 1-5 and can you remember what happens in S phase of the cell cycle?

2. Warm-Up!!! 4/23 Cell Cycle! 1 – Prophase 2 – Metaphase 3 - Anaphase 4 - Telophase 5 - Cytokinesis

3. Warm-Up!!! 4/23 Cell Cycle! S Phase = DNA is copied!!!

4. Warm-Up!!! 4/23 Cell Cycle! G1 = cell growth G2 = cell prepares for division (mitosis)

5. Warm-Up!!! 4/23 Cell Cycle! Interphase = Any time cell is not dividing!

6. Basics of the Human Body!!!

13. Levels of Organization The levels of organization in the human body are as follows: Cells Tissues Organs Organ Systems Organism

14. Levels of Organization Example: Cells-Neuron Tissues-Nervous Tissue Organs-Brain Organ Systems-Nervous System Organism-Human

15. Homeostasis Each cell in the human body is both an independent unit and a part of a larger community. Each of your 100 trillion cells must work together at all times to keep the body functioning correctly.

16. Homeostasis Short definition: the body’s ability to maintain a constant internal environment despite external changes.

17. Homeostasis For example: when you go outside on a really hot day your internal body temperature does not rise – the body takes action to keep you at a constant 98.6 degrees.

18. Homeostasis The body MUST always maintain homeostasis or risk harm: Homo = Same Stasis = constant

19. Homeostasis A perfect non-living example of homeostasis: The air conditioner in your house.

20. Homeostasis 1. Air conditioner set at 75 degrees. 2. If the temp. warms to 76 a sensor notes this and turns the air on. 3. When the sensor detects the temp has fallen back to 75 it shuts the air off. 4. A constant internal environment has been kept.

21. Homeostasis This kind of response is called Negative Feedback. That is, when a systems pushes things in the opposite direction in response to some kind of change.

22. Negative Feedback!

23. Homeostasis The body uses sorts of negative feedback loops to maintain homeostasis. Example: maintenance of a stable internal body temperature.

24. Homeostasis Body’s temperature sensor is the Hypothalmus deep inside the brain. So, the hypothalamus is probably part of which of the 11 body systems?

26. Homeostasis: 1.Body temperature drops to 97 degrees. 2.Nerve cells of the hypothalamus sense the temperature change. 3. Hypothalamus releases chemicals that tell muscle cells to ‘shiver’ to create heat.

27. Homeostasis: 4. Muscles produce heat that warms the body back to 98 degrees. 5. The nerve cells of the hypothalamus detects this increase in temperature and stops releasing the chemical that tells the muscles to shiver.

28. Negative Feedback!

29. Conclustion: Using negative feedback loops the body can keep its internal environment within very stable limits (we call this maintaining homeostasis). If this process is not working properly…..you have the potential for some serious bodily harm.