Chapter 13: Sleep, Dreaming and Biological Rhythms Flashcards
What is a biorhythm and what does it do?
an inherent timing mechanism that controls or initiates biological processes
What is a biological clock and what is interesting about a plant’s?
regulates feeding, sleeping and metabolic rates; they are endogenous
What are the 4 lengths of measurement for biorhythms?
1) Circadian (daily)
2) Circannual (annually)
3) Infradian (more than a day)
4) Ultradian (less than a day)
What happens to humans when their rhythm is left “free-running”? What determines this from species to species?
their rhythm lengthens; depends on light-related biology of the species (if they’re nocturnal it becomes shorter)
What is a zeitgeber and what is an example of one?
an environmental event that entrains biological rhythms; light/light pollution
What are the two types of SAD?
1) Phase retarded: desired sleep earlier in day
2) Phase delayed: desired sleep later in day
What is the “master biological clock” and where is it located in the brain?
the suprachiasmatic nucleus (SCN); in the hypothalamus just about the optic chiasm
What is proof the SCN regulates rhythms and what can help to entrain it’s clock?
still maintains rhythmic activity if all pathways to and from are cut; and is more active during light; regular feeding
What 3 other structures help the SCN in regulating?
the intergeniculate leaflet, raphe nucleus and the pineal gland
What type of synapses are the cells in the SCN connected through? What do they help to do?
inhibitory GABA synapses; keep time in synchrony
Where does the SCN receive light information from?
the retinohypothalamic tract (pRGC)
What compound is in the RGC’s in the retinohypothalamic tract that contributes to the SCN’s abilities? What are 3 substances it is composed of?
melanopsin; glutamate, substance P, pituitary adenylate cyclase
What part of the SCN does the retinohypothalamic tract excite? What does this part do in turn?
the ventrally located core; entrains the dorsally located shells to be rhythmic
What are the 4 steps in the main clock mechanism?
1) Transcription
2) Translation
3) Inhibition
4) Decay
What are the 4 ways for slave oscillators to be entrained?
1) SCN to nuclei in hypothalamus and thalamus (connect extensively with body)
2) Connects with pituitary endocrine (hormone release)
3) Sends indirect info to SC neurons which inhibit melatonin production
4) SCN releases hormones itself
What 2 hormones does the SCN regulate? What setting does it regulate each in?
melatonin (dark); glucocorticoids (light)
What does the SCN affect in other animals in relation to circannual rhythms? Example of Hamster and deer/sheep?
the reproductive behavior; hamster more in summer which is opposite of sheep/deer which is more in fall/early winter
What are the 4 states of waking and sleeping?
1) Waking state
2) Relaxed state
3) Drowsy state
4) Sleeping state
5) REM sleep
6) NREM sleep
What rhythm is associated with the waking state?
Beta rhythm (15-30hz)
What rhythm is associated with the relaxed state?
Alpha rhythm (7-11hz)
What rhythm is associated with the drowsy state?
Theta waves (4-7hz)
What rhythm is associated with the sleeping state?
Delta waves (1-3hz)
How many stages are there of NREM sleep? Which is the deepest?
4; known by some as stage 4 and others by 3b
How long is a typical NREM-REM sequence and how many times does it occur?
90 minutes; 5 times
When during a night’s sleep does more REM vs NREM occur?
more REM at end; NREM at beginning
What happens to your muscles and body temperature during REM sleep?
they lose tone (atonia); body temperature drops
What sleep stage do grinding, flailing and walking occur?
NREM
What did Freud believe dreams are?
symbolic fulfilment of unconscious wishes; manifest (actual) vs latent (true meaning)