endogenous pacemakers and exogenous zeitgebers Flashcards
what are pacemakers
structures inside the body that control The timings of biological rhythms.
What is the term for the processes in our body that follow a cycle?
biological rhythms
Cycles that repeat more than once every 24 hours, including stages of sleep and appetite.
ultradian
Cycles that repeat every 24 hours and include things like our sleep/wake cycle and the associated changes in body temperature.
circadian
Cycles that repeat less than once every 24 hours, including the female menstrual cycle.
infradian
What biological rhythm does melatonin control?
What does melatonin make us do?
sleep/wake cycle
sleepy/feel tired
Melatonin is produced by and released from the…
pineal gland
melatonin release
It is released the most at night
Its release is reduced, but not stopped during the day.
What effect does melatonin have on the brain?
It inhibits the wakefulness centres.
It activates the sleep centres.
At the start of the day the pineal gland decreases melatonin release. What does this result in?
People become more likely stay awake because they have less melatonin.
the wakefulness centres are released from inhibition and become active again.
which neurochemicals are involved in the sleep/wake cycle ?
melatonin
how does the pineal gland communicate
The pineal gland communicates with other cells via the bloodstream.
The pineal gland releases melatonin.
Melatonin travels to its target areas in the blood
Zia has just got home from work and it is winter, so it is dark outside. She sits on her sofa and feels really really sleepy.
Question 4. Explain the role of the pineal gland in making Zia feel sleepy.
At night, when there is reduced light, the pineal gland releases a hormone called melatonin. This melatonin travels through the bloodstream to the sleep and wakefulness centres. It activates the sleep centres, and inhibits the wakefulness centres, making us feel tired. For Zia, because it is dark outside, melatonin is released, which makes her feel sleepy.
What is the suprachiasmatic nucleus (SCN)?
A group of neurons in the hypothalamus.
The SCN is a group of neurons in the hypothalamus that controls the pineal gland through nerve impulses.
The SCN tells the pineal gland when to release releasing melatonin.
The Suprachiasmatic Nucleus
When the suprachiasmatic nucleus sends signals to the pineal gland, telling it to release less melatonin, what happens?
Our wakefulness centres become active making us stay awake.
Our sleep centres stop being active.
explain ralph et al for support of pacemakers
Ralph et al conducted a study investigating the sleep/wake cycle in hamsters.
Ralph et al had a control group with a normal sleep/wake cycle and an experimental group with an abnormal
21hr sleep/wake cycle.
It may not generalise to humans.
results of ralph et al
Both the abnormal and normal hamsters lost their sleep/wake cycle when their SCN was removed.
Transplanting the abnormal hamsters’ SCN into the normal hamsters caused them to adopt an abnormal
21 hour sleep/wake cycle.
Transplanting the normal hamsters’ SCN into the abnormal hamsters caused them to adopt a normal
24 hour sleep/wake cycle
the different structures involved in controlling the sleep/wake cycle
suprachiasmatic nucleus
pineal gland
melatonin
wakefulness centre
sleep centre
The SCN controls the pineal gland using nerve impulses: true or false
true
The SCN is located in the hypothalamus: true ad false
true
The SCN is a bundle of neurons: true or false
true
The SCN tells the pineal gland to release melatonin, which activates the sleep centre and inhibits the wakefulness centre. true or false
true
How exactly does light help the pacemakers stick to a regular 24 hour cycle?
light is detected by light receptors in the eyes
Julia complains that her baby is sleeping all day and keeping her awake all night.Using your knowledge of research into exogenous zeitgebers, discuss what Julia could do to encourage her baby to sleep more at night. (Total 8 marks)
AO1: define exz
how they interact with endp to regulate biological rhythms, give eg and exp (light, scn, pg, melatonin)
AO2: how light can be managed to encourage sleep at night and wakefulness in the day, inc social cues eg noise and meal times as exz
AO3: support for the role of light in regulating the swc, question whether its light or could be core body temp
