What is the hypothalamus?
The hypothalamus is a small, cone-shaped structure located near the center of the brain immediately below the thalamus. The hypothalamus has many nuclei and fiber tracts. It forms part of the walls and floor of the central chamber of the cerebral ventricles, which is known as the third ventricle. Neurons in the hypothalamus extend axons to the pituitary gland that is hanging on a stalk underneath the hypothalamus.
The hypothalamus controls many automatic functions of the body. Its overall function is to maintain normal, healthy conditions in the body by governing the autonomic nervous system and controlling pituitary output. Its specific functions are controlling the release of eight major hormones in the body, regulating body temperature, controlling food and water intake, controlling daily cycles in physiological state and behavior, mediating emotional responses, and regulating sexual behavior and reproduction.
If the hypothalamus is not functioning properly, the autonomic nervous system can send wrong neurosignals to the body that can make the victim feel stressed and emotionally empty. This can lead to disordered sleep, dysfunction of the immune system, altered body temperature, or multiple hormonal dysfunctions. These conditions often lead to depression, hyperactivity, malfunctioning of normal brain and limbic activities, or abnormal responses to stress. Disturbances in neural pathways that connect the hypothalamus and thalamus and control mood appear to be related to some of the symptoms of schizophrenia.
Obesity and related disorders are directly related to the critical role that the hypothalamus plays in the central regulation of appetite and metabolism. Insufficient production of antidiuretic hormone by the hypothalamus may cause diabetes insipidus. When the thirst center in the anterior hypothalamus is stimulated, polydipsia occurs, which can lead to polyuria.
Treatment of hypothalamic disorders depends on the cause of the dysfunction. If it is due to a tumor, the growth is either surgically removed or treated with radiation. If it is due to hormonal deficiencies, the missing hormones are replaced. Other specific treatments may be applied if the malfunction is due to infection, bleeding, or other causes.
The homeostatic function of the hypothalamus was suggested by Claude Bernard in the late 1800s. Many initial studies were focused on identifying the boundaries, structural components, nuclei, tracts, and interconnections of the hypothalamus. During the latter half of the twentieth century, interest shifted to the functions of the hypothalamus that were involved in emotional expression, disease, controlling metabolism, and producing neuroendocrine secretions. This emphasis has led to a better understanding and treatment of medical problems and chemical imbalances associated with hypothalamic dysfunctions.
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