Word: hypothalamus
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Dates: during 1980-1989
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Controlling the daily cycles is a cluster of 10,000 nerve cells -- altogether about the size of the head of a pin -- that are located in the hypothalamus, a segment of the brain. Some biological timepieces appear to take their cue from temperature or barometric pressure, but many are synchronized with the cycle of light and darkness caused by the rising and setting of the sun. Experiments conducted in caves, like the one in New Mexico, and others in special laboratories purposely remove all such cues. In Follini's module the temperature was a constant 69 degreesF, and the only...
...hypothalamus normally sends out a [hormone] signal that puts the reproductive system on 'go,'" Frisch says. If body weight is too low, the brain will not send any hormonal signals to the reproductive organs, and menstruation will not occur, she says. Once exercise is cut back and weight is regained, the menstrual cycle and ovulation will be restored, and pregnancy will be possible. "The situation is not irreversible," she says...
...experimental treatment with perhaps fewer ill effects involves a synthetic substance called nafarelin, similar to gonadotropin-relea sing hormone. Normally GnRH is released in bursts by the hypothalamus gland, eventually triggering the process of ovulation. But "if the GnRH stimulation is given continuously instead of in pulses," explains Dr. Robert Jaffe of the University of California, San Francisco, "the whole (ovulatory) system shuts off," and the endometrial implants "virtually melt away...
...Constitution is a bit less satisfying, it is probably because pinpointing the limits of a First Amendment right is more difficult than pinpointing a chemical imbalance in the hypothalamus. Each episode of the series, created by former CBS News President Fred W. Friendly, brings on a panel of experts who enact roles in hypothetical cases dramatizing Executive privilege, freedom of the press, school prayer, the right to life and other constitutional issues. President Ford and advisers like retired General Brent Scowcroft argue that classified information on covert CIA activity in the mythical country of Sierra Madre must be kept secret...
...When the hypothalamus finds the testosterone levels too high, as it does in the case of steroid abusers, it signals the pituitary to stop production. Problems can also arise in some cases after athletes stop taking the drugs and the hypothalamus fails to get the system started again...