Download Diapositiva 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.
1. Temperature decreases
_______ outdoors.
outdoors.
2. Thermometer registers temperature
decrease inside
3. Thermostat calls
____the
thefurnace
furnacefor
forheat
____
4. Furnace generates heat
_____
5. Temperature increases
______ inside
inside
6. Temperature reaches
_______the
thethermostat
thermostat
setting
7. Thermostat does
________
not call
thethe
furnace
furnace
for heat
8. Furnace stops
_____generating
generatingheat
heat
9. Temperature decreases
_______ inside
inside
1. Temperature ________
decreases outdoors.
skin
2. ________
registers body temperature
brain calls the _______
muscles for heat
3. ________
muscles shiver and generate heat
4. _________
5. Body temperature ___________
increases
6. Body temperature reaches the ______
setting
brain does not call the_______
muscles
7. __________
for heat
8. Muscles stop ____________________
shivering
decreases
9. Body temperature ________________
1. 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
What does a negative feedback look like?
1. The role of insulin is
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.
2. The role of glucagon is
To promote the breakdown of glycogen
into glucose.
To increase the glucose level in blood.
3. The line graph is an example of
Homeostasis
Negative feedback
Dynamic Equilibrium
4. Both, glucagon and insulin, are
hormones that work together to
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,
increases
blood glucose levels _____________after
eating.
insulin
The pancreas releases ______________.
Insulin stimulates cells throughout the body
glucose out of the bloodstream.
to take ________
Glucose taken out of the circulation is
stored in __________
and
liver
____________________,
or converted to
Skeletal muscles
fat
_______.
Within one or two hours after eating, the
decreases
level of blood glucose ______________
Then, pancreas releases ______________.
glucagon
Glucagon stimulates the cells of the
liver
_________
and skeletal muscles to break
down complex sugar and increase
glucose
____________
levels in the blood.
Glucagon also causes fat cells to break
down fats so that they can be used for the
glucose
production of ________________.
When blood calcium levels are
too high, the (gland) thyroid
_________
calcitonin
secretes (hormone) _________.
calcitonin
(Hormone) _______________
stimulates calcium deposition in
the bones. Therefore, calcium
leves in blood (increases
decreases
/decreases) ________________.
If calcium levels drop too low,
parathyroid
the (gland) ________________
PTH
secretes (hormone) _________.
PTH
(Hormone) ________________
stimulates bone cells to release
some of the calcium store in
bone into the bloodstream.
Then, calcium leves in blood
increases
(increases /decreases) ________.
What does a negative feedback look like?
1. State a title for the graph:
Glucose level in blood between 7 am
to 11 am
2. Identify chemical X.
3.
Insulin
Which individuals will most likely
need injections of chemical X?
Explain your answer
Individual #2 because he/she does
not produce insulin
4. State one reason for the change in
blood glucose level between 7:00
a.m. and 8:00 a.m.
They had a meal containing carbohydrates.
Or they had breakfast.
5.
What term refers to the relatively
constant level of blood glucose of
individual 1 between 9:00 a.m. and
11:00 a.m.?
Homeostasis
Steady state
Dynamic equilibrium.
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
What is a negative feedback?
1. How do you explain what a negative feedback is?
A negative feedback is a process that control and maintain
stable the vital signs
2. You are doing some exercise. Explain how your body maintains the
balance of CO2 level in blood.
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
3. Give a few examples of negative feedback from everyday life.
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? Homeostasis is a state of balance in the body.
2.- What is another word for “homeostasis”? Dynamic equilibrium or steady state
3.- Why is homeostasis constantly threatened?
Because the organism’s external an internal environment is constantly changing
4.- Explain how does an organism maintain homeostasis?
The organism detects changes in the environment and respond with an action
that return the organism’s system to normal
5.- As an example of maintaining homeostasis, how do organisms readjust body
temperature?
If temperature is above normal the body sweats,
if temperature is below normal the muscles shake
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”.
The constant small corrections that keep the internal environment
within the limits needed for survival
8.- What can interfere with homeostasis or dynamic equilibrium?
Microorganism and diseases