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28.2 Mechanisms of Homeostasis Sponge (Pg. 36) 1)Hypothesize how these climbers hang on to their body temperature.

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Presentation on theme: "28.2 Mechanisms of Homeostasis Sponge (Pg. 36) 1)Hypothesize how these climbers hang on to their body temperature."— Presentation transcript:

1 28.2 Mechanisms of Homeostasis Sponge (Pg. 36) 1)Hypothesize how these climbers hang on to their body temperature.

2 28.2 Mechanisms of Homeostasis 1)Hypothesize how these climbers hang on to their body temperature. His body is working inside to provide energy and to maintain a stable body temperature.

3 28.2 Mechanisms of Homeostasis Set up Cornell Notes on pg. 37 Topic: 28.2 Mechanisms of Homeostasis Essential Question(s): 1.On the top ½ of pg. 36 please create a double- bubble comparing and contrasting Negative and Positive feedback 2.On the bottom ½ of pg. 36 please draw your own negative feedback loop with a real example NOT used in class 2.1 Atoms, Ions, and Molecules 28.2 Mechanisms of Homeostasis

4 KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment.

5 28.2 Mechanisms of Homeostasis Homeostasis is the regulation and maintenance of the internal environment within the narrow ranges that support human life. It is a delicate balance. Temperature Fluids Salts pH nutrients

6 28.2 Mechanisms of Homeostasis Conditions within the body MUST remain within a narrow range. Homeostasis involves keeping the internal environment within set ranges.

7 28.2 Mechanisms of Homeostasis 7 Human Internal Environment Protects our cells from external changes Is relatively constant, despite an ever- changing outside environment (98.6 degrees)

8 28.2 Mechanisms of Homeostasis 8 Stimulus: rising blood sugar Response: blood sugar returns to normal= homeostasis Negative Feedback: The control system (brain) sends signals/instructions to effectors (muscles and glands) to stabilize the body activated by an imbalance corrects an imbalance, brings body back to Homeostasis Pancreas receptors detect high blood sugar The control center signals the pancreas to secrete insulin Effector: Insulin causes liver cells to take up sugar in the blood

9 28.2 Mechanisms of Homeostasis 9 Your control center (brain) is like a thermostat Has a set temperature (98.6) If it is too hot- sends signals to effectors (sweat glands) to lower body temp (ex: sweat) If too cold- sends signals to effectors to raise body temp (ex: shiver) How does a thermostat work? Air conditioner Heater

10 28.2 Mechanisms of Homeostasis 10 Change occurs in internal or external environment 100*

11 28.2 Mechanisms of Homeostasis 11 Receptors Sensors: Gather data, and Send signals to the control center

12 28.2 Mechanisms of Homeostasis 12 The brain receives data, and compares it with “set point”, sends messages to effectors

13 28.2 Mechanisms of Homeostasis 13 Work to return the body to balanced levels- delivers messages to target organs/glands

14 28.2 Mechanisms of Homeostasis 14 Targets respond to change, and body returns to homeostasis

15 28.2 Mechanisms of Homeostasis 15 Body temperature rises above set point due to the environment 100* Real life example:

16 28.2 Mechanisms of Homeostasis 16 Skin sensory receptors send signals to brain

17 28.2 Mechanisms of Homeostasis 17 The hypothalamus detects the difference from the set point: 98.6* and signals effectors

18 28.2 Mechanisms of Homeostasis 18 Messages sent to sweat glands

19 28.2 Mechanisms of Homeostasis 19 You sweat, body temperature lowers to normal (98.6)

20 28.2 Mechanisms of Homeostasis How are negative feedback loops necessary for homeostasis? Feedback compares current conditions to set ranges. Negative feedback counteracts change Keeps environment stable Negative Feedback Loop Holding breath, CO 2 levels rise, Control system forces exhale, inhale O 2 / CO 2 level returns to normal

21 28.2 Mechanisms of Homeostasis 21 Positive Feedback: Process by which changes cause additional similar changes, producing unstable conditions- pushes away from homeostasis

22 28.2 Mechanisms of Homeostasis Positive feedback increases change –Important when rapid change is needed –EX: Torn vessel stimulates release of clotting factors platelets fibrin white blood cell red blood cell blood vessel clot

23 28.2 Mechanisms of Homeostasis At your table, please explain the difference between a negative feedback loop and positive feedback loop? Negative feedback loop counteracts change away from set points. Positive feedback loops increases change away from set points.

24 28.2 Mechanisms of Homeostasis Homeostasis is the regulation and maintenance of the internal environment within the narrow ranges that support human life. Body temperature is normal Normal amounts of blood and other bodily fluids With your neighbor, please make a list of external or internal factors that would affect your body’s homeostasis.

25 28.2 Mechanisms of Homeostasis Disease Stress Rest Lifestyle (drinking, smoking, diet) Injury Illness (fever, infection) Dehydration/Starvation Please make a list of external or internal factors that would affect your body’s homeostasis.

26 28.2 Mechanisms of Homeostasis A disruption of homeostasis can be harmful Sensors fail to detect changes Wrong messages sent Messages fail to reach their targets Serious injuries overwhelm the body Viruses or bacteria change the body’s internal chemistry

27 28.2 Mechanisms of Homeostasis Short term effects Last a few days or weeks Ex: A cold virus enters your body Within a few days your immune system begins to kill the virus

28 28.2 Mechanisms of Homeostasis Long term effects Causes long term damage to the body Ex: diabetes

29 28.2 Mechanisms of Homeostasis 29 Homework On the top ½ of pg. 37 draw a double- bubble map, comparing and contrasting negative and positive feedback. Make sure you give examples of each.

30 28.2 Mechanisms of Homeostasis 30 Negative Feedback Positive Feedback Corrects an imbalance Ex: temperature regulation Returns body to homeostasis Causes additional changes Ex: Contractions during childbirth Moves body away from homeostasis stimuli receptors Control center effectors


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