BIO 12 Lecture 28: Bio_12_-_Human_Physio_-_28
Jeff Koo
Bio 12
Human Physio
Spring 2020
4 Units
Thyroid Hormone Disorders:
● Hyperthyroidism – excess in thyroid hormone
○ Causes: tumours, thyroid stimulating immunoglobin
○ Symptoms: goiter (enlarged thyroid gland), nervousness, insomnia, anxiety, high
heart rate, Graves’ disease, weight loss
○ Treatments: removal of part of the thyroid gland, drugs blocking synthesis of T3
and T4 or block conversion of T4 to T3
● Graves’ disease – autoimmune disorder
○ Abnormal antibodies against the TSH receptor are produced
■ Thyroid gland thinks it needs to produce T3 and T4
■ Lose the idea of negative feedback
○ Most common cause of hyperthyroidism
○ Most common cause of thyroid enlargement in developed countries
● Hypothyroidism – deficiency of thyroid hormone
○ Causes: under active thyroid gland, lack of iodine in diet
○ Symptoms: goiter, slowed heart rate, slowed speech, fatigue, cold-intolerance,
cretinism, stunted growth and weight gain
○ Treatments: exogenous thyroid hormone T4 (thyroxine)
● Iodine deficiency
○ Leaves the thyroid gland unable to produce T3 and T4
○ Lack of negative feedback leads to excess TSH secretion
○ TSH stimulates growth of thyroid gland, goiter may be present
Anterior pituitary = increase in TSH, more thyroid hormone will be produced (increase)
Hypothalamus = excess thyroid hormone will send signals to the hypothalamus that it has
enough, so it is downregulated
Key Concepts:
● Thyroid hormone is necessary for normal growth, development, and maintenance of
many tissues
● Thyroid hormone mobilizes energy stores to increase the metabolic rate
● Many disorders are attributed to varying levels of circulating thyroid hormone
Synthesis of Hormones in the Adrenal Cortex
● Adrenocorticoids
● Steroid hormones derived from cholesterol
o Presence of different enzymes yields different hormones
● Lipophilic/hydrophobic hormones
o Membrane solubility
o Synthesis
o Release
Document Summary
Symptoms: goiter (enlarged thyroid gland), nervousness, insomnia, anxiety, high. Treatments: removal of part of the thyroid gland, drugs blocking synthesis of t3 heart rate, graves" disease, weight loss and t4 or block conversion of t4 to t3. Abnormal antibodies against the tsh receptor are produced. Thyroid gland thinks it needs to produce t3 and t4. Most common cause of thyroid enlargement in developed countries. Causes: under active thyroid gland, lack of iodine in diet. Symptoms: goiter, slowed heart rate, slowed speech, fatigue, cold-intolerance, Leaves the thyroid gland unable to produce t3 and t4. Lack of negative feedback leads to excess tsh secretion. Tsh stimulates growth of thyroid gland, goiter may be present cretinism, stunted growth and weight gain. Anterior pituitary = increase in tsh, more thyroid hormone will be produced (increase) Hypothalamus = excess thyroid hormone will send signals to the hypothalamus that it has enough, so it is downregulated.
