Chapter 14 Outline

Chapter 14 Outline - Chapter 14 Biological Rhythms Sleep...

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Chapter 14: Biological Rhythms, Sleep and Dreaming I. Many Animals Show Daily Rhythms in Activity and Physiological Measures i. Circadian rhythms - rhythms that last about a day- 24 hours. ii. Nocturnal animals stay up at night, diurnal animals active during day. iii. Other animals w/o watches attend to a biological clock. iv. Can be determined by hamster on while activity chart. b. Circadian rhythms are generated by and endogenous clock i. Cycle slightly longer than 24 hours when hamster free runs on his own clock. ii. Period - time from when one thing happens to when it happens again in a cycle. iii. Phase shift - a shift in the activity over time. iv. Entrainment - intentionally shifting the rhythm. v. Zeitgeber - any cue used to synchronize activity with environment. c. Circadian rhythms allow animals to anticipate changes in the environment. i. So they can be out when theyre supposed to. II. An Endogenous Circadian Clock is Located in the Hypothalamus i. Suprachiasmatic nucleus (SCN) - serves as biological clock. 1. Still shows rhythm even when removed from body. b. Transplants prove that the SCN produces a circadian rhythm. i. Some hamsters have mutant 20 hour SCN which changes others when they receive it in a transplant. c. In mammals, light information from the eyes reaches the SCN directly i. In some vertebrates, pineal gland is sensitive to light. ii. Retinohypothalamic pathway in mammals which project to optic chasm and SCN. iii. Specific melanospin pigment in retinal ganglion cells which detect light, not rods and cones. d. Circadian rhythms have been genetically dissected in flies and mice i. Genes to produce Clock and Cycle proteins that combine to form a dimer- pair of attached proteins. 1. produces period and cytochrome proteins which produce Tau. ii. Per/cry/tau enters nucleus and stops Clock/Cycle from transcribing new proteins until it breaks down, which takes 24 hours. iii. Glutamate from retina axons released into cell which increases production of per. iv. People who feel different better in morning carry different “Clock” gene than night owls. III. Many Biological Events Display Rhythms Shorter than a Day i. Ultradian - rhythms with frequencies greater than once a day. 1. Humans isolated from cues show 90 minute cycle of daydreaming. ii. More rapid ultradian rhythms in smaller animals.
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1. Ultradian rhythms not controlled by SCN.
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This note was uploaded on 04/07/2008 for the course PSYCH 2230 taught by Professor Smith, d during the Fall '06 term at Cornell.

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Chapter 14 Outline - Chapter 14 Biological Rhythms Sleep...

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