MCELLBI C61 Chapter Notes - Chapter 20: Circadian Clock, List Of Disney Comics By Carl Barks, Pineal Gland
17 May 2020
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Sleep: daily periods of inactivity and reduced alertness characterized by distinctive physiological properties of brain activity. The amount of time we sleep everyday varies across species: bats sleep 19, mice and rats sleep 12, cows and elephants sleep 4, and humans sleep 8 hours a day. Humans spend a third of their lifetimes asleep, roughly 263k hours over 90 years. The regular cycle of sleep and wakefulness in our lives is a biological rhythm. Follows a circadian pattern, having a periodicity of approximately 24 hours. Other examples of circadian rhythms are body temperature variations, synthesis of cortisol by the adrenal gland, + synthesis of melatonin in the pineal gland. Circadian rhythms are found in many organisms, not just animals. Plants, fungi, and even single-celled creatures exhibit circadian rhythms. In plants, the opening and closing of owers and leaves is a circadian rhythm.
