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ch 5 - Consciousness Body Rhythms and Mental States Chapter...

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Consciousness: Body Rhythms and Mental States Chapter 5
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Biological Rhythms A biological clock in our brains governs the waxing and waning of hormone levels, urine volume, blood pressure, and the responsiveness of brain cells to stimulation. Many of these rhythms continue to occur even in the absence of external time cues; they are endogenous , or generated from within.
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Biological Rhythms Infradian rhythms - period longer than 24-hours yearly- bird migration, hibernation 28-days- human menstrual cycle Circadian rhythms - 24-hours sleep Ultradian rhythms - period shorter than 24 hours 90 minute REM cycle 4 hour nasal cycle
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Circadian Rhythms Some biological rhythms, called circadian rhythms, occur approximately every 24 hours. The best-known circadian rhythm is the sleep-wake cycle, but there are hundreds of others. body temp- 1 degree C per day
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The Body's Clock Circadian rhythms are controlled by a biological clock , or overall coordinator. The clock is located in a tiny teardrop-shaped cluster of cells in the hypothalamus called the suprachiasmatic nucleus (SCN) . Neural pathways from special receptors in the back of the eye transmit information to the SCN and allow it to respond to changes in light and dark.
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The Body's Clock The SCN then sends out messages that cause the brain and body to adapt to these changes. regulates hormone and neurotransmitter levels melatonin - secreted by pineal gland during dark hours Other clocks also exist and some may operate independently of the SCN. For most circadian rhythms, the SCN is regarded as the master pacemaker.
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When the Clock Is Out of Sync Under normal conditions, the rhythms are synchronized, just as wristwatches can be synchronized. peaks may occur at different times, but they occur in phase with one another. If you know when one rhythm peaks, you can predict when another will do so.
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When the Clock Is Out of Sync When your normal routine changes, your circadian rhythms may be thrown out of phase with one another. internal desynchronization often occurs when people take airplane flights across several time zones. Sleep and wake patterns usually adjust quickly, but temperature and hormone cycles can take several days to return to normal. bright lights may be used to re-synchronize body rhythms
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Moods and Long-term Rhythms In human beings, long-term cycles have been observed in things like the threshold for tooth pain conception rates. Folklore holds that our moods follow similar rhythms particularly in response to seasonal changes and, in women, to menstrual changes do they?
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Does the Season Affect Moods? some people report feeling depressed every winter when periods of daylight are short and improve in mood each spring, as daylight increases This pattern that has come to be known as seasonal affective disorder (SAD) bright light treatment and negative ion exposure treatment have been reported to be effective could be related to a deficiency in melatonin
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Does the Menstrual Cycle Affect Moods?
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