How a Negative Feedback Mechanism works? Do Now: It is winter and the temperature in your classroom has dropped to 60ºF, low below 70ºF to which the thermostat is set. The electrician advised you that the thermostat was not working. Explain how does the thermostat work to regulate the temperature of the room

Temperature decreases outdoors. 2. Thermometer registers temperature It is winter and the temperature in your classroom has dropped to 60ºF, low below 70ºF to which the thermostat is set. The electrician advised you that the thermostat was not working. Explain how does the thermostat work to regulate the temperature of the room Temperature decreases outdoors. 2. Thermometer registers temperature decrease inside 3. Thermostat calls the furnace for heat 4. Furnace generates heat 5. Temperature increases inside 6. Temperature reaches the thermostat setting 7. Thermostat does not call the furnace for heat 8. Furnace stops generating heat 9. Temperature decreases inside Temperature _______ outdoors. 2. Thermometer registers temperature decrease inside 3. Thermostat ____ the furnace for ____ 4. Furnace generates _____ 5. Temperature ______ inside 6. Temperature _______ the thermostat setting 7. Thermostat ________ the furnace for heat 8. Furnace _____ generating heat 9. Temperature _______ inside

Your body´s “thermostat” is set at 98ºF (37ºC). How is this temperature maintained when you are in very hot or cold environment. Temperature ________ outdoors. 2. ________ registers body temperature 3. ________ calls the _______ for heat 4. _________ shiver and generate heat 5. Body temperature ___________ 6. Body temperature reaches the ______ 7. __________ does not call the_______ for heat 8. Muscles stop ____________________ 9. Body temperature ________________ decreases skin brain muscles muscles increases setting brain muscles shivering decreases

During exercise the CO2 level increases. 2. Heart registers CO2 increase in blood 3. Brain calls the respiratory muscles to speed up 4. Respiration rate increases 5. CO2 level decreases in blood 6. Heart detects CO2 decrease 7. Brain call the respiratory muscles to slow down 8. Respiratory rate decreases 9. CO2 increases in blood

How does homeostasis work in plants? Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose an excessive amount of water.

Carbon Dioxide CO2 Oxygen O2, Water Vapor H2O(v) Carbon dioxide, water, and sunlight Leaf pores are open. Guard cells are filled up with water Leaf pores are closed. Guard cells shrink because the lack of water The plant would not carry out photosynthesis and eventually would die closed open

open open closed closed open open closed The presence of water To control the exchange of gases and the performance of photosynthesis

Do Now: List 3 examples of negative feedbacks in living things How stomata regulate photosynthesis How our body regulates a steady body temperature How our body regulates CO2 levels in blood How a thermostat regulates temperature in a building

What does a negative feedback look like?

3. The line graph is an example of  1. The role of insulin is   2. The role of glucagon is  3. The line graph is an example of   4. Both, glucagon and insulin, are hormones that work together to To take glucose out of the bloodstream and store it in the liver an muscles. To decrease the glucose level in blood. To promote the breakdown of glycogen into glucose. To increase the glucose level in blood. Homeostasis Negative feedback Dynamic Equilibrium To maintain a constant glucose level in blood

How does homeostasis work? Fill in the blanks of the following paragraph. Use the words on the list. The same word can be use more than once.  Glucose, glucagon ,fat, increase, skeletal muscles, decrease, insulin, liver,   For those who ate breakfast or lunch today, blood glucose levels _____________after eating. The pancreas releases ______________. Insulin stimulates cells throughout the body to take ________ out of the bloodstream. Glucose taken out of the circulation is stored in __________ and ____________________, or converted to _______. Within one or two hours after eating, the level of blood glucose ______________ Then, pancreas releases ______________. Glucagon stimulates the cells of the _________ and skeletal muscles to break down complex sugar and increase ____________ levels in the blood. Glucagon also causes fat cells to break down fats so that they can be used for the production of ________________. increases insulin glucose liver Skeletal muscles fat decreases glucagon liver glucose glucose

Then, calcium level in blood (increases /decreases) ________. When blood calcium levels are too high, the (gland) _________ secretes (hormone) _________. (Hormone) _______________ stimulates calcium deposition in the bones. Therefore, calcium leves in blood (increases /decreases) ________________. If calcium levels drop too low, the (gland) ________________ secretes (hormone) _________. (Hormone) ________________ stimulates bone cells to release some of the calcium store in bone into the bloodstream. Then, calcium level in blood (increases /decreases) ________. thyroid calcitonin calcitonin decreases parathyroid PTH PTH increases

What does a negative feedback look like?

State a title for the graph: Identify chemical X. Which individuals will most likely need injections of chemical X? Explain your answer State one reason for the change in blood glucose level between 7:00 a.m. and 8:00 a.m. What term refers to the relatively constant level of blood glucose of individual 1 between 9:00 a.m. and 11:00 a.m.? Glucose level in blood between 7 am to 11 am Insulin Individual #2 because he/she does not produce insulin They had a meal containing carbohydrates. Or they had breakfast. Homeostasis Dynamic equilibrium.

What is a negative feedback? 1. How do you explain what a negative feedback is?   2. You are doing some exercise. Explain how your body maintains the balance of CO2 level in blood. 3. Give a few examples of negative feedback in living things A negative feedback is a process that control and maintain stable the vital signs During exercise CO2 level increases in blood. The body speed up the respiration rate in order to release more CO2 and decreases the CO2 level Keeping body temperature near 98 F Balance CO2 level in blood Exchange of gases and photosynthesis in plants Maintenance of glucose level in blood Maintenance of calcium level in blood

1.- What is homeostasis? 2.- What is another word for “homeostasis”?   3.- Why is homeostasis constantly threatened?   4.- Explain how does an organism maintain homeostasis? 5.- As an example of maintaining homeostasis, how do organisms readjust body temperature? 6.- Draw a graph that shows a regular pattern of body temperature. Explain what that graph means related to homeostasis. 7.- Describe what is “dynamic equilibrium”. 8.- What can interfere with homeostasis or dynamic equilibrium? Homeostasis is a state of balance in the body. Dynamic equilibrium Because the organism’s external an internal environment is constantly changing The organism detects changes in the environment and respond with an action that return the organism’s system to normal If temperature is above normal the body sweats, if temperature is below normal the muscles shake The constant small corrections that keep the internal environment within the limits needed for survival Microorganism and diseases