1. What is a negative feedback?
DO NOW: Why can´t we keep holding our
breaths indefinitely?
It is winter and the temperature in your classroom has been soraing to 85ºF, high above 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.
Your body´s “thermostat” is set at 98ºF (37ºC). How is this temperature maintained when you are in very hot or cold environment.

2. 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

3. 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

4. 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

5. What does a negative feedback look like?

6. 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 promote glucose entry into cells
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

7. 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

8. Then, calcium leves 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 leves in blood (increases /decreases) ________.
thyroid
calcitonin
calcitonin
decreases
parathyroid
PTH
PTH
increases

9. What does a negative feedback look like?

10. 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
Steady state
Dynamic equilibrium.

11. 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.

12. 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

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

14. 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 from everyday life.
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

15. 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 or steady state
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