1. Example Hormone Regulating Metabolic Homeostasis
Thyroxine
Example Hormone Regulating
Metabolic Homeostasis

2. Thyroxine Hormone Secreted by the thyroid gland
Structure contains four atoms of iodine
The hormone targets ALL body cells
Stimulates metabolism in the target cells
increases metabolic rate
increases rates of protein synthesis
triggers growth

3. Thyroxine and Temperature Regulation
Chemoreceptors in hypothalamus sense body temperature decreasing
Through a series of steps, the decrease in body temperature causes the release of thyroxine from the thyroid
Thyroxine triggers increased metabolism in all body cells (chemical reactions in cells)
Metabolism increases the generation of body heat
Body warms.
This is an example of negative feedback!

4. Without thyroxine, metabolism is slower
lack of energy, feeling tired
forgetfulness and depression
weight gain
feeling cold
impaired brain development

5. What causes thyroxine deficiency?
The body does not make iodine, so it is an essential part of your diet. Iodine is found in various foods.
If you do not have enough iodine in your body, you cannot make enough thyroid hormone.
Thus, iodine deficiency can lead to enlargement of the thyroid (goiter)
This has the effect of increasing the thyroid's ability to trap more iodide, compensating for the iodine deficiency and allowing it to produce adequate amounts of thyroid hormone.

6. International Council for Control of Iodine Deficiency Disorders (ICCIDD)
Add this information underneath the thyroxine deficiency table in your notes
The ICCIDD is an international non-governmental organization with the commitment to preventing iodine deficiency.
The ICCIDD illustrates how scientists cooperate and collaborate to address international concerns.

7. 6.6.U2
Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
Describe the structure and function of thyroxin.
Outline thyroxin’s role in body temperature regulation.
List symptoms of thyroxin deficiency.
D.5.NOS
Cooperation and Collaboration between groups of scientists – the International Council for the Control of Iodine Deficiency Disorders includes a number of scientists who work to eliminate the harm done by iodine deficiency.
Outline consequences of iodine deficiency.
State the goal of the ICCIDD.