Endogenous Pacemakers Flashcards
What are endogenous pacemakers?
Internal mechanisms that govern biological rhythms
What are the two main endogenous pacemakers?
- The SCN (suprachiasmatic nucleus)
- The pineal gland
What is the SCN?
A tiny cluster of cells located behind the eyes, detects changes in light levels and send signals to other parts of the brain in order to regulate the sleep wake cycle
Where does the SCN send signals to?
The pineal gland which begins to produce melatonin
What is melatonin?
The hormone and neurotransmitter which regulates our sleep pattern
What did Morgan do?
Bred ‘mutant’ hamsters by manipulating their SCN so they had a circadian rhythm of 20 hours instead of 24 hours
What did Morgan find?
The SCN plays a key role in controlling circadian rhythms
What did Folkard do?
Conducted a case study of Kate Aldcroft who lived in a cave for several weeks, the researcher asked her to play the tune ‘amazing grace’ at what she thought was the same time twice a day
What did he find?
After 25 days her sleep rhythm hwd altered to a 30 hour cycle but her temperature had stayed the same, suggesting there is more than one internal clock
Why do people with Smith-Magenis syndrome find it difficult to fall asleep?
They have inverted melatonin levels
What helps them sleep?
Taking melatonin tablets which supports the idea that the pineal gland/melatonin play an important role in controlling biological rhythms
