Enogenous pacemakers and exogeneous zetigebers

What are the two things which influence biological rhythms?

1. Internal body clocks (Endogenous pacemakers)
2. External cues in the environment (Exogeneous zeitgebers)

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Definition of endogenous pacemaker

Internal body clocks that regulate many of our biological rhythms, such as the influence of the SCN on our sleep wake cycle.

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What is the sleep wake cycle?

A daily cycle of biological activity based on a 24-hour period (circadian rhythm) that is influenced by regular variations in the environment, such as the alternation between night and day.

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What is a Exogeneous zeitgebers?

External cues that may affect or entertain our biological rhythms such as the influence of light on our sleep wake cycle.

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What is the suprachiasmatic nucleus? (SCN)

Tiny bundle of nerve cells located in the hypothamulus in each hemisphere of the brain, primary endogenous pacemakers in the human species. Its influential in maintaining circadian rhythms such as sleep wake cycle.

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Where does the SCN lie?

Just above the optic chiasm

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What does the SCN do?

Receives information about light directly from the optic chiasm. Continues even when are eyes are closed enabling the biological clock to adjust to changing patterns of daylight whilst we are asleep.

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Explain the chipmunk animal study

Decoursey 2000, used 30 chipmunks destroyed the SCN connections in the brain who were then returned to their natural habitat and observed for 30 days. The sleep wake cycle disappeared by the end of the study by a significant proportion had been killed by

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Talk about the pineal gland

A pea like structure in the brain just behind the hypothalamus, SCN passes info to here. During the night it increases the production melatonin- a chemical that induces sleep and is inhibited during periods of wakefulness, it's been seen as a casual facto

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What is entrainment?

When our biological clocks are rested by external environmental factors. Sleep and wakefulness must be determined by an interaction of internal and external factors.

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What role does light play?

Key zeitgeber in humans, resets the body's main endogenous pacemaker - SCN. Plays role in the maintenance of the sleep wake cycle, has another indirect effect on key processes in the body that control functions like hormone secretion and blood circulation

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Talk about social cues?

In infants the initial sleep wake cycle is pretty much random, at about 6 weeks the circadian rhythms begin and by 16 weeks most babies are entrained. Schedules imposed by parents are likely to be a key influence here like mealtimes and bedtimes.

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What does research suggest?

Adapting to local times for eating and sleeping is an effective way of entraining circadian rhythms and beating jet lag when travelling long distances.

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Enogenous pacemakers and exogeneous zetigebers

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