Human Phys Notes PP

Genetic defects in alpha receptors tend to have normal thyroid hormone levels. Scientists found this by screening many people, as they did not initially know what to look for. Since cardiovascular problems are common, this could not have been used as a screening tool for someone with alpha receptor defects. Instead, they used the hypathalmic-pituitary-thyroid hormone pathway as it is very sensitive to hormone defects. Of the hormones, T4 is the most abundant hormone in the blood, however T3 is the biologically active form. T4 is transported actively across the cell membrane into the cytoplasm and the receptor is already bound to DNA in the un-liganded form. Overall, the symptoms of thyroid disease are variable; two people with this disease are likely to have very little symptom overlap.