BIO 337 Lecture Notes - Lecture 6: Circadian Rhythm, Chronobiology, Zeitgeber
Document Summary
Recognizes the local time of day (sundial) Daily rhythm - peaks once a day - constant conditions to determine if its circadian. Heliotropic plants - inside (still move in reference to the sun without stimulation by sun) Persists in the absence of environmental cues. Period off from 24 hours - starts a little later (precise) Period is less than 24 hours (slope - measure of period (tau)) Humans - longer than 24 hours (~24. 2) Daily (diel, nycthemeral) - every 24 hrs. Diurnal - event occurring between dawn and dusk. Nocturnal - even occurring between dusk and dawn. T - zeitgeber period - when lights turn on - time 0. Phi - phase, instantaneous state of an oscillation within a period. Psi - difference in position of two phases (phase angle difference) delta(phi) - displacement of an oscillation along the time axis (phase shift) Input (light) photoreceptor --(entrainment pathway)--> circadian pacemaker. -(output pathway)--> regulated system (activity) output (overt rhythm)
