13.1 Flashcards
A Clock for All Seasons
What are diurnal animals?
Organisms that are chiefly awake during the day and sleep when it’s dark
What is a circadian rhythm?
Day-night rhythm; biorhythm that cycles in approximately one day
What is metabolic syndrome?
Combinations of medical disorders, including obesity and insulin abnormalities, that collectively increase the risk of developing cardiovascular disease and diabetes
What may be the root cause of metabolic syndrome?
Disruptions of our biological clocks (specifically eating and sleep-wake)
What is a biological clock?
A neural system that times behavior by producing biorhythms
What are biorhythms?
Cyclical changes in behavior or bodily functions
How long are circannual rhythms?
About a year
What are two examples of circannual rhythms?
Animals’ migratory and mating cycles
How long are infradian rhythms?
Longer than a day and less than a year?
What is an example of an infradian rhythm?
The human menstrual cycle
How long is a circadian rhythm?
About a day
What is an example of a circadian rhythm?
Human sleep-wake cycle
How long is an ultradian rhythm?
Less than a day
What is an example of an ultradian rhythm?
Human eating behavior
What is the possible origin of biorhythms?
It was a way for our bodies to adapt to changing day/night lengths throughout the year (as well as climate and food for migratory animals)
How did experiments on plants give us an understanding of the biological clock?
Plants were shown to have cycles of opening their leaves in the day and closing them at night even without external cues (light, temp., etc.). Therefore, there must be an endogenous biological clock that controls these cycles
What is a free-running rhythm
Rhythm of the body’s own devising in the absence of all external cues
What did the study on human’s sleep-wake cycle in the absence of external cues tell us about free-running cycles?
When Ps can set their own sleep-wake time, their cycle lasts 25-27 hours. The internal biological clock we have for sleep-wake cycles has a preferred period
What is a Zeitgeber?
An environmental event that entrains biological rhythms; German for “time giver”
What is the most potent Zeitgeber for many animals, including humans?
Light
What does it mean to entrain a biorhythm?
To determine or modify the period of a biorhythm
What is one explanation for seasonal affective disorder (has to do with biorhythms…)
That, for people in northern latitudes, the low levels of sunlight in the winter do not entrain the circadian rhythm and it’s disrupted.
What does it mean for someone to be phase-retarded?
Their desired sleep time comes earlier in the day
What does it mean for someone to be phase-advanced?
Their desired sleep time comes later in the day
