Thyroid Hormone
Feedback System
Simulation
Simulation at jondarkow.com
1. Run the model with the initial conditions. Graph the
results of the TSH, TH, and Metabolism in the graph provided.
Explain the type of feedb
...
Thyroid Hormone
Feedback System
Simulation
Simulation at jondarkow.com
1. Run the model with the initial conditions. Graph the
results of the TSH, TH, and Metabolism in the graph provided.
Explain the type of feedback the system seems to have. Use
the data to justify your answer.
TSH has negative feedback from TH yet TH has positive feedback from TSH. As the amount of TSH
increases the number of TH increases, yet as the amount of TH increases the amount of TSH
decreases.
2. If there is a gene mutation to the TSH receptors on the thyroid, what should happen to
each variable over time? Graph how you predict the TSH, TH, and Metabolism levels will change
over time with a mutation to the TSH receptors.
3. Reset to initial conditions.
Adjust the relative amounts of TSH receptors to 0 (simulating a severe mutation to TSH receptors),
and run the model. Explain the results.
As there are no receptors of TSH, TH production can not be simulated, leading to an unregulated
increase in TSH.
4. Hypothyroidism is a condition that leads to the thyroid under-producing the thyroid
hormone. Predict how hypothyroidism would affect metabolism.
The TSH amount would steadily increase to a high amount until enough is produced to stimulate TH
production. Then the amount of TSH would decrease.
5. Reset to initial conditions.
Simulate hypothyroidism by reducing the relative amount of the "release of TH", and running the
model. Compare how metabolism was affected in the simulation by reducing the “release of TH”
with your prediction in question #4.
Accurate except for the release of TH was later than expected.
6. Reset to initial conditions.
Hyperthyroidism is a condition that leads to the thyroid overproducing the thyroid hormone.
Simulate hyperthyroidism by adjusting the "TH release" to its maximum. Run the model.
a. Justify if dynamic homeostasis is still maintained.
Homeostasis is maintained as metabolism swings relatively closely within the normal range of
minima and maxima along with having the same average.
b. If dynamic homeostasis is still maintained, explain how hyperthyroidism may affect a
patient.
Rapid swings in metabolism. Periods of hunger and then feeling very full.
7. Many physiological systems have Setpoints. A Setpoint is a particular value a dynamic
system fluctuates around. In physiological systems, a set point is the goal value of homeostasis. For
example, the average set point for an adult female's heart rate is 68 beats per minute. 68 bpm
would be a typical female's set point. In chaos theory mathematicians often refer to set points in
dynamical systems as attractors.
In this model, experiment with (or perturb) the initial conditions of metabolism and TH production
to discover the set point. Why are setpoints important in organisms?
Setpoints enable normal bodily function and give both inhibitors and stimulators a goal value.
8. A robust dynamic system is one that returns to the setpoint, despite large changes in one
or more of the variables. Would you
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