Ch. 8.1. Rhythms of Waking and Sleeping Flashcards
The _____ _______ ______ leads birds to fly south for the winter and back north in the summer
The endogenous circannual rhythm
The ____ ______ ____ causes animals to have a day rythm (24 h) that is not easily changed
endogenous circadian rhythms
What evidence indicates that humans have an internal
biological clock?
People who have lived in an environment with a light-dark schedule much different from 24 hours fail to follow that schedule and instead become wakeful and sleepy on about a 24-hour basis
When do people report their most pleasant and least pleasant hours during the day?
Regardless of whether people started this procedure at 10 a.m. or 5 p.m., most reported their most pleasant mood around 5 p.m. and their least pleasant mood at around 5 a.m.
Why do people at the eastern edge of a time zone awaken earlier than those at the western edge on their weekends and holidays?
The sun rises earlier at the eastern edge than at the western edge. Evidently, the sun controls waking–sleeping schedules even when people follow the same clock time for their work schedule.
A convenient way to classify people as morning/evening people? What age-group is the most evening person across culture?
What is the middle of your sleep in holidays?
Adolescence..
The main driver of the circadian rhythms
The Suprachiasmatic Nucleus (SCN) in the hypotalamus
What evidence strongly indicates that the SCN produces the
circadian rhythm itself?
SCN cells produce a circadian rhythm of activity even if they are kept in cell culture isolated from the rest of the body.
Also, when hamsters received transplanted SCN neurons, their circadian rhythm followed the pattern of the donor animals.
How does light reset the biological clock?
A branch of the optic nerve, the retinohypothalamic path, conveys information about light to the SCN. The axons comprising that path originate from special ganglion cells that respond to light by themselves, even if they do not receive input from rods or cones.
People who are blind because of cortical damage can still syn-
chronize their circadian rhythm to the local pattern of day and night. Why?
If the retina is intact, melanopsin-containing ganglion cells can still send messages to the SCN (jus a bove the optic chiasm), resetting its rhythm.
How do the proteins TIM and PER relate to sleepiness in
Drosophila?
The proteins TIM and PER remain low during most of the day and begin to increase toward evening. They reach high levels at night, promoting sleep. They also feed back to inhibit the genes that produce them, so that their level declines toward morning.
Melatonin is produced in the ____ ____ ? The production is regulated by ______ ?
Pineal gland, posterior to thalamus.
Suprashiasmatic nucleus (SCN)
If you want to get to sleep on time, what should you avoid?
Short-wavelength light late in the evening
When is melatonin mostly released?
At night, for all species
