Lesson 10: Circadian Rhythms Flashcards
What are biological rhythms?
they are CYCLICAL changes in PHYSIOLOGICAL systems
that have EVOLVED as the ENVIRONMENTS in which organisms live in have cyclical changes e.g day/night summer/winter
What are the three types of biological rhythms?
(Can’t Use Internet)
Circadian
Ultradian
Infradian
What are circadian rhythms
any cycle that lasts 24 HOURS
What do Circadian rhythms optimise?
1) an organisms’ PHYSIOLOGY
2) BEHAVIOUR to best meet the varying demands of the DAY/NIGHT cycle
What are Circadian rhythms driven by?
Suprachaismatic nuclei (SCN) in the HYPOTHALAMUS
What does the Suprachaismatic nuclei (SCN) act as
a PACEMAKER (controlling the rate at which something occurs)
Why must the SCN be constantly reset?
so our bodies are in SYNCHRONY with the outside world
What does NATURAL light do in order to co-ordinate the activity of circadian rhythms in the body
1) Natural light SETS the SCN to the correct time in a process called PHOTOENTRAINMENT
2) SCN then uses this information to co-ordinate activity of circadian rhythms throughout the body
According to the sleep-wake cycle, what do lightness and darkness act as?
EXTERNAL signs that determine when we feel the need to SLEEP and WAKE up
When does our strongest drive to sleep occur?
between 2:00am- 4:00am
AND
1:00pm-3:00pm
What gland releases MELATONIN
PINEAL gland
When is the release of melatonin from the pineal gland at its PEAK?
during hours of DARKNESS
How does Melatonin induce sleep?
it INHIBITS the NEURAL MECHANISMS that promote WAKEFULNESS
Fill in the blank:
The production of _______ supresses the production of melatonin
Light
What type of control is sleep and wakefulness under?
Homeostatic control