thyroid hormones diagram

thyroid tsh pituitary gland function hormone anatomy t3 t4 vector thyroxine system axis medicine production neuron human endocrinology hypothyroidism healthcare secretion health illustration endocrine control regulation stimulating vital homeostasis iodine diagram neuroendocrine organ triiodothyronine calcitonin thyrotropin trh brain hypothalamus hormonal blood bone gut heart rate liver vessel metabolism clinic infographic