1. Hint: go back to your “Diffusion” notes.
Warm-Up (3/3)
Name
Date
Period
If high concentrations of glucose build up outside a cell, how does a cell absorb some of the glucose?
Hint: go back to your “Diffusion” notes.

2. 2C.1a: Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Illustrative example: temperature regulation in animals
2C.1b: Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces systemic change.
Illustrative example: lactation in mammals
2C.1c: Alterations in the mechanisms of feedback often results in deleterious consequences.
Illustrative example: dehydration in response to decreased antidiuretic hormone (ADH)
2C.2a: Organisms response to changes in their environment through behavioral and physiological mechanisms.
Illustrative example: shivering and sweating in humans

3. Levels of bodily function B
Negative Feedback
Homeostasis is the balance of levels of two things.
Negative feedback regulates to return systems to homeostasis.
Levels of bodily function B
Levels of hormone A

4. Negative Feedback Homeostasis is the balance of levels of two things.
For example, temperature regulation
Negative feedback regulates to return systems to homeostasis.
Hippocampus hormones
98.6°F Temperature

5. Negative Feedback Homeostasis is the balance of levels of two things.
For example, temperature regulation
if temperature drops,
hormones released
Negative feedback regulates to return systems to homeostasis.
Hippocampus hormones
92.3°F Temperature
Temperature
Re-regulated

6. Negative Feedback Homeostasis is the balance of levels of two things.
For example, temperature regulation
if temperature drops,
hormones released,
temperature returns to normal.
Negative feedback regulates to return systems to homeostasis.
Hippocampus hormones
98.6°F Temperature

7. Negative Feedback Homeostasis is the balance of levels of two things.
For example, temperature regulation
if temperature drops,
hormones released
Negative feedback regulates to return systems to homeostasis.
Hippocampus hormones
92.3°F Temperature
Shivering

8. Negative Feedback Homeostasis is the balance of levels of two things.
For example, temperature regulation
if temperature raises,
hormones released
Negative feedback regulates to return systems to homeostasis.
101.2°F Temperature
Hippocampus hormones
Sweating

9. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
Negative feedback regulates to return systems to homeostasis.
Antidiuretic hormone (ADH) from kidneys
Normal water balance

10. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
if cells become dehydrated,
ADH released
Negative feedback regulates to return systems to homeostasis.
Antidiuretic hormone (ADH) from kidneys
Dehydrated cells
Kidneys release water
(urine more concentrated)

11. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
if cells become dehydrated,
ADH released,
water balance restored.
Negative feedback regulates to return systems to homeostasis.
Antidiuretic hormone (ADH) from kidneys
Normal water balance

12. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
if cells become overhydrated,
less ADH released
Negative feedback regulates to return systems to homeostasis.
Over-hydrated cells
Antidiuretic hormone (ADH) from kidneys

13. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
if cells become overhydrated,
less ADH released
Negative feedback regulates to return systems to homeostasis.
Over-hydrated cells
Antidiuretic hormone (ADH) from kidneys
Kidneys absorb water
(urine more diluted)

14. Antidiuretic hormone (ADH) from kidneys
Negative Feedback
Homeostasis is the balance of levels of two things.
For example, hydration regulation
if cells become overhydrated,
less ADH released,
water balance restored.
Negative feedback regulates to return systems to homeostasis.
Antidiuretic hormone (ADH) from kidneys
Normal water balance

15. Critical Thinking Question #1
Insulin is a hormone ligand which binds to the insulin receptor and stimulates the absorption of glucose from the bloodstream into cells. When blood glucose levels are high, the pancreas increases insulin levels; when blood glucose levels are low, the pancreas releases less insulin. A graph is plotted below showing the levels of glucose and insulin in a single person over a period of 24 hours.
Explain why the graph shows relatively low concentrations of insulin at 12 hours but relatively high concentrations of glucose, and predict what the glucose curve would look like if the pancreas failed to produce insulin.

16. 2C.1a: Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point.
Illustrative example: temperature regulation in animals
2C.1b: Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces systemic change.
Illustrative example: lactation in mammals
2C.1c: Alterations in the mechanisms of feedback often results in deleterious consequences.
Illustrative example: dehydration in response to decreased antidiuretic hormone (ADH)
2C.2a: Organisms response to changes in their environment through behavioral and physiological mechanisms.
Illustrative example: shivering and sweating in humans

17. Levels of bodily function B
Negative Feedback
Positive feedback further moves the system away from homeostasis.
Levels of bodily function B
Levels of hormone A

18. Levels of bodily function B
Negative Feedback
Positive feedback further moves the system away from homeostasis.
Hypothetical example:
Bodily function B drops,
Levels of hormone A
Levels of bodily function B

19. Levels of bodily function B
Negative Feedback
Positive feedback further moves the system away from homeostasis.
Hypothetical example:
Bodily function B drops,
Hormone A promotes activated,
Levels of hormone A
Levels of bodily function B

20. Levels of bodily function B
Negative Feedback
Positive feedback further moves the system away from homeostasis.
Hypothetical example:
Bodily function B drops,
Hormone A promotes activated,
bodily function B drops further.
Levels of hormone A
Levels of bodily function B

21. Levels of bodily function B
Negative Feedback
Positive feedback further moves the system away from homeostasis.
Hypothetical example:
Bodily function B drops,
Hormone A promotes activated,
bodily function B drops further,
bodily function B drops further.
Levels of hormone A
Levels of bodily function B

22. Negative Feedback
Positive feedback further moves the system away from homeostasis.
Actual example: Lactation
Milk gets suckled,
Hormone released to produce milk,
More milk get suckled,
More milk produced.
Milk Hormone
Milk production

23. Critical Thinking Question #2
The sjf1 gene encodes a transcription factor which activates several genes, including its own gene. Explain how a signal transduction pathway which leads to activation of the sjf1 gene will be amplified through positive feedback.

24. Closure
On the piece of white paper from the back, answer the following question:
Name
Date
Period
Explain how chronic (long-term) exposure to high glucose levels leads to insensitivity to insulin signaling, a condition known as diabetes mellitus.
Scale 1 – 10