Chapter 14: Biological Rhythms & Sleep Flashcards
entrainment (n.)
the process of synchronizing a biological rhythm to an environmental stimulus
circadian rhythm (n.)
a pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period
ultradian rhythms (n.)
rhythms that are shorter than 24 hours; can last from minutes to several hours
infradian rhythms (n.)
rhythms that have periods longer than a day
What brain region controls circadian rhythms?
Suprachiasmatic nucleus (SCN) of the hypothalamus
What are the four biological functions of sleep?
Energy conservation, niche adaptation, body restoration, and memory consolidation
When an animal continues to display an activity cycle without any external cues about the time of day, the cycle is said to be ________.
free-running
What is a zeitgeber?
An environmental cue that synchronizes circadian rhythms
What are the four brain regions that regulate sleep?
Basal forebrain, brainstem reticular, pons, hypothalamus
What sleep neurotransmitter does the basal forebrain regulate?
GABA
What sleep neurotransmitter does the pons regulate?
ACh
What sleep neurotransmitter does the brainstem reticular formation regulate?
ACh and norepinephrine
What sleep neurotransmitter does the hypothalamus regulate?
Hypocretin
What does the basal forebrain regulate for sleep?
Slow wave sleep (SWS)
What does the brainstem reticular formation regulate for sleep?
Wakefulness
What does the pons regulate for sleep?
REM sleep
What does the hypothalamus regulate for sleep?
Organization of sleep patterns
What happens to sleep patterns after a lesion in the suprachiasmatic nucleus?
There is some rhythmicity to the light/dark cycle; no free-running when exposed to constant light
What happens with the SCN is removed and maintained in vitro?
Circadian rhythm is still maintained
What happens if a tau mutant SCN (20 hour) is implanted?
The recipient takes on the 20 hour circadian cycle of the donor
How does entrainment occur?
Light stimulates melanopsin-containing ganglion cells which releases glutamate at the SCN; glutamate increases transcription of per gene, producing entrainment
Describe the functioning of the molecular clock.
Clock and Cycle form dimer; binds to DNA and promotes transcription of per and cry; per, cry, and tau form complex which inhibits Clock/Cycle activation, which inhibits per/cry transcription; per/cry break down, ending inhibition; feedback loop takes 24 hours.
What are delta waves?
Low frequency, high amplitude waves
At what stage of sleep do delta waves begin?
Stage 3 SWS
What are alpha waves?
Low amplitude, high frequency waves
Describe stage 1 SWS.
Alpha rhythm decreases, presence of vertex spikes
Describe stage 2 SWS.
Sleep spindles and K complexes
Describe stage 3 SWS.
Onset of delta waves
Describe stage 4 SWS.
At least 1/2 delta waves
Describe REM sleep.
Return to high frequency; “paradoxical sleep”
