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BIOLOGICAL RHYTHMS: IT’S A MATTER OF TIME

BIOLOGICAL RHYTHMS: IT’S A MATTER OF TIME. Text: Rhythms of Life Russell Foster and Leon Kreitzman. What are Biological Rhythms? What are Rhythms?. What is a rhythm?. Pattern Sequence Regularity Progression Time Measure Beat.

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BIOLOGICAL RHYTHMS: IT’S A MATTER OF TIME

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  1. BIOLOGICAL RHYTHMS: IT’S A MATTER OF TIME Text: Rhythms of Life Russell Foster and Leon Kreitzman

  2. What are Biological Rhythms? • What are Rhythms?

  3. What is a rhythm? Pattern Sequence Regularity Progression Time Measure Beat

  4. Rhythm = sequence of events that repeat themselves in the same order and with the same time interval, over and over again. Biological rhythm: a biological event or function with a pattern of activity that is repeated over and over again at a constant time interval.

  5. What are examples of Biological Rhythms? Biological Rhythms Heart rate Breathing Hormone secretion Menstrual cycle Body temperature Sleep/wake cycle Time

  6. Biological Rhythms are the product of an internal biological timekeeping system which is controlled by a biological clock • Chronobiology

  7. Two Broad Categories of Biological Rhythms • high frequency – • Ultradian • Those that have a constant relationship with environmental rhythms – • Have a geophysicalcounterpart

  8. ENVIRONMENTAL RHYTHMS • Semi-Daily Rhythms • Tidal • Daily Rhythms • Solar • Monthly • Lunar • Quarterly • Seasons • Annual • Longer than a year

  9. Spinning of earth on its axis 24h – solar day Movement of earth around sun 365 days – year Tilting of earth on its axis seasons Movement of moon around earth 24.53 days – lunar month 24.8h – lunar day Geophysical

  10. Types of biological rhythms with a geophysical counterpart: infradian

  11. What Kind of Organisms Have Biological Rhythms?

  12. What is the purpose of having a biological timekeeping system? • Promotes organism’s ability to survive by coordinating its activities with changes in the environment • Coordinates internal processes

  13. STROMATOLITE

  14. Many organisms have several kinds of biological rhythms

  15. Alexander the Great 4th Century BC Tamarind Tree

  16. de Mairan, 1729 endogenous

  17. Du Monceau 1759 Circadian rhythms do not depend on temperature changes Linneaeus 1751 Circadian rhythms are genetically determined

  18. Linneaeus1751

  19. de Candolle 1832 When not exposed to environmental day/night rhythms plant leaves opened and closed on a 22 – 23 h cycle instead of a 24 h cycle Free-running rhythm

  20. Circadian rhythms are endogenous. • Endogenous rhythms are not exactly 24h. • The periods of Circadian rhythms are genetically determined. • Endogenous rhythms are temperature-compensated

  21. Bees – 1910 Forel 1929 Beling 1950s Renner Drosophila – 1950s Pittendrigh

  22. PACEMAKER TARGET TISSUE BIOLOGICAL RHYTHMS (overt rhythms)

  23. ZEITGEBER TRANSDUCER PACEMAKER Endogenous, free-running rhythm INTERMEDIATE ELEMENTS TARGET TISSUES BIOLOGICAL RHYTHMS

  24. Activity (locomotor) rhythm

  25. Chronobiology Biological rhythm Ultradian Infradian Circadian Circatidal Circalunar Circannual Endogenous Free-running Pacemaker Target tissue Overt rhythm Nocturnal Diurnal LL DD LD 12:12 Study of biological timekeeping Cyclical, repeated variation in a biological function High frequency – repeats many times in a day Repeats at intervals much longer than 24 hours Approximately a day (24 hours) Approximately every 12.4 hours ( with the tide) Approximately once a month Approximately once a year Internally generated rhythm Not synchronized to external signals A structure that generates a rhythm Tissue whose function is regulated by the pacemaker A visible, measurable rhythm Active at night Active during the day Constant light Constant darkness 12 hours of light; 12 hours of dark

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