Sleep Flashcards
What are circadian rhythms?
- functions that display a rhythm of about 24 hours
diurnal
active during the light
nocturnal
active during the dark
Rhythms may be…
- behavioral,
- physiological, or
- biochemical
What generates body rhythms
An endogenous clock
What do rhythms entrain to
light-dark cycles
biological clock leads to…
- precise tmiing
- endogenous clock is not quite 24 hr
- is entrained (set) to light/dark cycles
Biological clocks- rat study
- When researches shift the light cycle for rats, behavior also shifts
- with continuous dim light, behavior becomes free running
What allows for entrainment?
- light (visual input)
- meals
- sleep
- jobs/class (overnight shifts)
- activity/exercise
several of these inputs are also regulated by the biological clock
What is disrupted in animals with SCN lesions?
circadian rhythms
Where is the biological clock located?
In the SCN- located above the optic chiasm in the hypothalamus
What can isolated SCN neurons do?
- maintain electrical activity synchronized to the previous light cycle
What do most retinal ganglion cells contain, and what does this do?
most retinal ganglion cells contain melanopsin, a special photopigment that makes them sensitive to light
What does the retinohypothalmic pathway consist of?
retinal ganglion cells that project to the SCN
ganglion cells in the retinohypothalamic pathway rely on rods and cones: T/F
false, they DO NOT rely on rods and cones
Retinohypothalamic Pathway two steps
- Light causes glutamate release in SCN
- Synchronizes SCN neurons to each other and light/dark cycle
How many distinct classes of sleep are there? What are they called?
- There are two distinct classes of sleep
- Non-REM sleep and REM sleep
What is non-REM (NREM) sleep?
- characterized by lack of rapid eye movements
- can be divided into three stages