Name: ______________________________ Fam: ___________ Tuesday, November 11, 2014 Cell City Analogy
In a far away city called Grant City, the main export and production product is the steel
widget. Everyone in the town has something to do with steel widget making and the entire
town is designed to build and export widgets. The town hall has the instructions for widget
making, widgets come in all shapes and sizes and any citizen of Grant can get the
instructions and begin making their own widgets. Widgets are generally produced in small
shops around the city; these small shops can be built by the carpenter's union (whose
headquarters are in town hall).
After the widget is constructed, they are placed on special carts which can deliver the
widget anywhere in the city. In order for a widget to be exported, the carts take the
widget to the postal office, where the widgets are packaged and labeled for export.
Sometimes widgets don't turn out right, and the "rejects" are sent to the scrap yard
where they are broken down for parts or destroyed altogether. The town powers the
widget shops and carts from a hydraulic dam that is in the city. The entire city is enclosed
by a large wooden fence, only the postal trucks (and citizens with proper passports) are
allowed outside the city.
Match the parts of the city (underlined) with the parts of the cell.
1.Mitochondria _____________________________________________
2. Ribosomes
_____________________________________________
3. Nucleus
_____________________________________________
4.Endoplasmic
Reticulum
_____________________________________________
5. Golgi
Apparatus
_________________________________________________________
6. Protein
_____________________________________________
7. Cell
Membrane
_____________________________________________
8. Lysosomes
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9. Nucleolus
_____________________________________________
Name: ______________________________ Fam: ___________ Wednesday, November 12, 2014 Homeostasis and Negative Feedback
Homeostasis is one of the fundamental characteristics of living things. It refers to the
maintenance of the internal environment within tolerable limits. All sorts of factors affect the
suitability of our body fluids to sustain life; these include properties like temperature, salinity,
acidity, and the concentrations of nutrients and wastes. Because these properties affect the
chemical reactions that keep us alive, we have built-in physiological mechanisms to maintain
them at desirable levels.
When a change occurs in the body, there are two general ways that the body can respond. In
negative feedback, the body responds in such a way as to reverse the direction of change.
Because this tends to keep things constant, it allows us to maintain homeostasis. On the other
hand, positive feedback is also possible. This means that if a change occurs in some variable,
the response is to change that variable even more in the same direction. This has a de-stabilizing
effect, so it does not result in homeostasis.
Positive feedback is used in certain situations
where rapid change is desirable.
To illustrate the components involved
in negative feedback, we can use the
example of a driver trying to stay near
the speed limit. The desired value of a
variable is called the set point. Here,
the set point is a speed of 55 mph; in
controlling body temperature, the set
point would be 98.6 degrees. The
control center is what monitors the
variable and compares it with the set
point. Here, the control center is the
driver; for body temperature, it would
be the hypothalamus of the brain. If the
variable differs from the set point, the
control center uses effectors to reverse
the change. Here, the effector is the
foot on the accelerator pedal; in
controlling body temperature, it would include the glands that sweat and the
muscles that shiver.
Homeostasis and Negative Feedback Questions 1. Define homeostasis from the readings. 2. List some factors that homeostasis regulates in your body. 3. Define negative feedback. Explain how this relates to the concept of homeostasis? 4. Define positive feedback. Explain how this relates to the concept of homeostasis? 5. Explain how homeostasis is like driving a car. 6. Describe what the cartoon would be like if it was drawn of positive feedback. 7. Create your own cartoon of a negative feedback system of the Respiratory system or the Circulatory system. Include and explain all the components of a negative feedback system (a set point, a control center and an effector). Name: ________________________________ Fam: ___________ Thursday, November 13, 2014 Living Environment
• DO NOW: Why can´t we keep holding our breaths indefinitely? • What do you think will happen if we were to try? Why? _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ It is winter, it is snowing outside and the temperature in your house has been decreasing to 55ºF, low above 70ºF to which the thermostat is set. Explain how the thermostat works to regulate the temperature of the room. Missing words: Heat, Call, Do not Call, Increases, Decreases, Generates, Reaches, Stop 1. 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 _______
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? 1. 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 _____________
Name: ________________________________ Fam: ___________ Friday, November 14, 2014 Use the examples from Thursday’s homework to answer the following exercise. Follow the same format to explain what the diagram is describing. _________________________________________
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