Question

Describe the physiological basis of circadian rhythms and the mechanisms by which birds navigate during migration. Include in your answer: a. a description of circadian rhythms and zugunruhe b. a description of the molecular and physiological mechanisms for entraining circadian rhythms and the timing of seasonal movements in birds c. a description of the current hypothesis for bird navigation using Earth’s magnetic field

Answer 1

Description of circadian rhythms and zugunruhe.

Seasonal and circadian rhythms of melatonin have been associated migratory nocturnal restlessness or Zugunruhe. Zugunruhe or nocturnal migration, the melatonin release is same as non-migratory period, melatonin levels are higher at night during the day. Bird’s circadian rhythms are direct links between the mechanism of the clock and features of the cognitive task. The central clock could have different which is potentially modified and effects on different behavioral mechanisms. The elements of some cognitive tasks may influence and balance the circadian rhythms. Set of mechanisms involved multi channel clocks, sets of linked mechanisms that produce similar patterns of timings but also have some level of independence due to tight connections with behavioral activities. The hormonal and neural mechanisms can also balance circadian rhythms in birds.

Description of the molecular and physiological mechanisms for entraining circadian rhythms and the timing of seasonal movements in birds

Oscillatory mechanisms produced by hypothalamus and pineal gland. The sites for activity of melatonin are present in a combination in the suprachiasmatic nuclei SCN of the hypothalamus. The SCN neurons upon synchronization, generate a robust, self sustained rhythms. The neuronal and hormonal gives signaling pathways and SCN then entrains circadian clocks which is present in peripheral tissues like pineal, heart, liver etc.

Bird’s circadian rhythms are direct links between the mechanism of the clock and features of the cognitive task. The central clock could have different which is potentially modified and effects on different behavioral mechanisms. The elements of some cognitive tasks may influence and balance the circadian rhythms. Set of mechanisms involved multi channel clocks, sets of linked mechanisms that produce similar patterns of timings but also have some level of independence due to tight connections with behavioral activities. The hormonal and neural mechanisms can also balance circadian rhythms in birds.

Description of the current hypothesis for bird navigation using Earth’s magnetic field.

Birds can navigate using earth’s magnetic field’s due to the presence of cryptochromes in their eyes are responsible to orient themselves by detecting magnetic fields called a sense like magnetoreception.

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