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Chapter 23: Circadian Rhythms & Sleep

When did circadian rhythms originate?

A. Soon after the origin of life

B. After the dinosaur extinction at the end of the Cretaceous

C. After the Permian extinction 250 million years ago

D. At the onset of the Cambrian explosion about 530 million years ago

E. At the transition from prokaryotes to eukaryotes

A. Soon after the origin of life is the correct answer.

How does entrainment differ from synchronization?

A. Entrainment works by always setting the circadian clock when the amount of light exceeds a certain threshold.

B. Entrainment works by always setting the circadian clock when the amount of light falls below a certain threshold.

C. Entrainment allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

D. Synchronization allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

E. Entrainment and synchronization are 2 names for the same thing.

C. Entrainment allows continuity in clock phase to be robust with respect to temporary changes in light levels, such as from cloud cover or volcanoes.

What is the primary, central pacemaker brain area in mammals?

A. The striatum

B. The SCN of the hypothalamus

C. The nucleus interpositus of the cerebellum

D. The lateral geniculate nucleus of the thalamus

E. The superior colliculus deep layers

B. The suprachiasmatic nucleus of the hypothalamus is the central pacemaker brain area in mammals.

What is the retinal output to the SCN?

A. Magnocellular retinal ganglion cells

B. Kinocellular retinal ganglion cells

C. Motion-selective retinal ganglion cells

D. Intrinsically photoreceptive retinal ganglion cells

E. Starburst amacrine cells

D. Intrinsically photoreceptive retinal ganglion cells compose the retinal output to the suprachiasmatic nucleus.

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