Head and neck anatomy speech (phonation). In addition to the teeth, other structures that aid chewing are the lips, cheeks, tongue, hard palate, soft palate, and floor of the mouth. Several glands of the endocrine system are found within the head and neck. Endocrine means that the secretion is used within the body. Endocrine glands are termed as ductless and release their secretions directly into the blood. The endocrine system is under the direct supervision of the nervous system, using the negative feedback principal of homeostasis, to create hormones which act as chemical instant messengers. The hypothalamus connects directly to the pituitary gland, both
Endocrine disruptor BDE-47, affects the reproductive system and thyroid gland of female rats in doses of the order of those to which humans are exposed. Low concentrations of endocrine disruptors can also have synergistic effects in amphibians, but it is not clear that this is an effect mediated through the endocrine system. Critics have argued that data suggest that the amounts of chemicals in the environment are too low to cause an effect. A consensus statement by the Learning and Developmental Disabilities Initiative argued that "The very low-dose effects of endocrine disruptors cannot be predicted from high-dose studies, which contradicts the standard