- Medial Preoptic nucleus - which controls urinary bladder pressure and decreases heart rate and blood pressure
- Supraoptic nucleus (located just over the optic nerve) - which releases oxytocin (uterine contraction) and vasopressin (blood pressure).
- Paraventricular ("between the ventricles") nucleus - which releases oxytocin, vasopressin and corticotropin releasing hormone (CRH, ultimately responsible for triggering the adrenal cortex to release cortisone/cortisol).
- Anterior hypothalamic nucleus - which controls panting, sweating, internal temperature regulation and release thyrotropin (regulates the thyroid).
- Suprachiasmatic (literally "Over the 'X'" referring to the crossover point of the optic nerve) nucleus - which releases vasopressin and regulates circadian rhythm (day/night, sleep/wake cycle)
- Lateral portions of preoptic and supraoptic nuclei
- Lateral nucleus - which regulates thirst and hunger (via secretion of a hormane called Orexin or Hypocretin, which is also shown to affect wakefulness)
- Dorsomedial Hypothalamic Nucleus - which regulates blood pressure and heart rate, as well as stimulating contractions in the intestines
- Ventromedial Nucleus - which regulates satiety (Orexin again, plus another hormone known as Gallanin), and control of neuroendocrine glands (such as thyroid, pancreas, ovaries, testes and adrenals)
- Arcuate Nucleus - which releases Gonadotropin-releasing hormone (GRH, aka Luteinizing hormone releasing hormone, LHRH) to regulate ovaries, releases dopamine (to alter prolactin release from pituitary and regulate lactation), and regulates feeding behaviors - largely in the form of altering taste to seek out essential nutrients.
- Mammillary nuclei - part of the Mammillary Bodies (named for their shape, not their function) - This is actually one end of the Limbic System, and is involved in memory.
- Posterior Nucleus - involved in the release of norepinephrine, a neurotransmitter similar to adrenaline, this area regulates blood pressure (causes arterial contraction), pupil dilation and shivering.
- Lateral Nucleus - actually a continuation of the Anterior Lateral Nucleus
There are two divisions - Anterior, also known as "Adenohypophysis" (named for its effect on glands) makes and secretes:
- Adrenocorticotropic Hormone (ACTH) which stimulates the adrenal gland. ACTH release is stimulated by CRH from the Paraventricular Nucleus)
- Thyroid-Stimulating Hormone
- Growth Hormone
- Prolactin (regulates mammary milk production and ovaries/uterus)
- Luteinizing Hormone (in women) / Interstitial Cell Stimulating Hormone (men) which regulates ovaries/testes
- Follicle Stimulating Hormone which stimulate ova release from ovaries
- melanocyte stimulating hormone which leads to melanin (skin pigment) formation
So, that's a lot of functions. If the Thalamus is the controller for neuron signals, hypothalamus is the controller for chemical signals. Together with the basal ganglia (next topic) they form the "diencephalon" which is essentially the *core* of the brain, and is the bare minimum structures necessary for most of what we think of as the essential functions of the brain apart from conscious thought.
Not bad for something about the size of a walnut. Kind of makes you rethink those prejudices against dinosaurs, right?
Until next time, "Take care of your Brain, it's the only one you've got!"