Why Do we Sleep and Dream? Flashcards
inherent timing mechanism that controls or initiates various biological processes
biorythym
biorhythms are linked to
cycle of days and seasons produced by earths rotation around the sun
humans largely evolved as ________ animals and our behaviour is dominated by _______ ______ of daylight activity and nocturnal sleep
- equatorial
- circadian rhythm
do biorhythms regulate metabolic activity?
yes
rhythms are _____
endogenous (come from within)
neural systems that times behaviour
biological clock
ex birds migrate before it gets cold
biological clocks synchronize behaviour to the _____ _____ of a real day and makes ________ about tomorrow
- temporal passage
- prediction (allows us to prepare physiologically and cognitively)
biological clock regulates: (4)
feeding time, sleeping time, metabolic activity, regulate gene expression
circadian =
circannual=
infradian =
ultraradian =
daily
yearly
less than a year
less than a day
rhythm of the body’s own devising in the absence of all external cues
ex?
free running rhythms
- biological clock in the absence of light
without input from external cues, our body has its own rhythm with a period of ___ to ___ hours
25 to 27 hours
animals expand and contract their sleep period as?
sleep related lighting period expands or contracts
hamsters are _____
- in constant darkness, free running periods are _____ than 24 hours
- constant light, they are _____ than 24 hours
nocturnal
- shorter
- longer
sparrows are _____
- in constant darkness, free running periods are _____ than 24 hours
- constant light, they are _____ than 24 hours
diurnal
- longer
- shorter
environmental event that entrains the biological rhythms; a time setter; the property that allows entrainments of a biological clock
zeitgebers
ex, light resets the biological clock
determines or modifies the period of a biorythm
entrainment
a ______ allows an animal to synchronize its daily activity across the seasonal clock
entrained biological clock
light pollution and jet lag are examples of?
zeitgebers
is harder to adjust when traveling eat - west or west to east
west to east
persistant asynchronous rhythms are associated with ? (5)
- altered sleep
- altered temp rhythm
- fatigue
- stress
- reduced success by sport teams
main pacemaker of circadian rythms; located just above the optic chiasm
- the master clock
suprachiasmatic nucleus
the _____ and the ____ also display clocklike activity (brain regions)
intergeniculate leaflet and pineal gland
nearly every cell int he body has its own ?
clock
the SCN is close to what?
and the cells of the SCN are more active (increased metabolic and electrical activity) when?
light information in the brain
- in the light period
if the SCN is damage what happens
daily activities occur haphazardly
SCN neurons maintain rhythmic activity in the absence of
input and output
what happens if the SCN neurons are isolated from one another ?
each remains rhythmic but he rythmicity of some cells is different than that of other cells (needs to be sunchronizied in relation to each other to respond to environmental cues)
neural route from a subset of cone receptors in the retina to the SCN
- allows light to entrain rhythmic activity SCN
retinohypothalamic
what are the 3 characteristics of the retinohypothalamic pathway
- begins with specialized retinal ganglion cells that contain photosensitive pigments melanopsin
- pRGCs axons bilaterally innervate SCN via retinohypothalamic tract
- the retinohypothalamic tract activates core cells
_____ neurons are not rhythmic but that entrain ___ neurons which are rythmic
core, shell
these ganglion can respond to blue wave lengths of light even without getting info from the cones and rods
pRGCs (cores and shells)
how do ppl who are congenitally blind(problem with rods and cones) maintain biological rhythms
still getting entrainment from blue wave length cells (pRGC)
–> cores and shells
pathway of retinohypothalamic tract
- photsensitive retinal ganglion cells respond to blue light
- retinohypothalamic tract carries info about light changes to core cells in SCN
- signal from SCN core neurons entrains shell neurons
- SCN drives slave oscillators and recieved signals from the other brain and body areas
SCN’s circadian rhythm is usually entrained by?
morning light and evening light
SCN can be disrupted or entrained by ? (4)
- sudden changes in light
- arousal
- moving
- feeding
through which pathways do nonphotic events influence the SCN rhythm
intergeniculate leaflet and raphe nucleus
what are the 2 groups of circadian neurons and what do they control
- M- cells: control mornign activity and need light for entrainments
- E- cells: control evening activity and need darkness for entrainment
what may explain differences in morning people ad evening people
individual differences in genes and activity or circadian E or M cells (some ppl have more of one)
- chronotypes are due to differences in SCN shell nuerons
explain the feedback loops of circadian rhythms
proteins are first made and then combine, called a dimer for two proteins, which inhibits the production of its component proteins
–> dimer then degrades and process starst again
SCN pacemaker drives a number of ___________, each of which controls the rhythmic occurance of one behaviour (ex, body temp)
- slave oscillators
SCN may drive slave oscillators via ? (3)
hormones, proteins, NT
the master oscillator is where?
SCN
4 functions of SCN cells in pacemaking circadian rhthyms
- SCN neurons send axonal connections to nuclei close by in the hypothalamus and thalamus, which then pass on entraining signal
- SCN connects with pituitary endocrine neurons to control hormones release to entrain many body tissues
- SCN instructs autonomic neurons in the spinal cord to inhibit the pineal gland from producing melatonin
- SCN cells themselves release hormones
the SCN control melatonin release from the pineal gland so that melatonin circulates when? and does what?
- during the dark phase of the circadian cycle
- influences/ promotes rest and digest
SCN control the release of ______ from the ________ so that they circulate during the light phase of the circadian cycle
- this does what?
- glucocorticoids
- adrenal gland
- mobilizes glucose for cellular activity
in rats, when melatonin is low in the lengthened spring time days, the gonads?
enlarge = more sex
pacemaking produced by the SCN is a product of its ____ cells, which activate _____ _______ via both chemical and anatomical connections
shell cells,
slave oscillators
when days are long, the SCN _____ melatonin secretion by the pineal gland, as days shorten, the melatonin _________ period _______ and the ________ period _______
- inhibits
- inhibition, shortens
- release period, lengthens
cognitive events necessitate changes in gene expression, turning genes on or off
–> as much as ___ % of the genome is under ________ _______ of the circadian rhythm
- 10%
- epigenetic control
what serves a s good index for the time and place at which things should happen
time of day
cognitive activities occur without the ?
- this means is ti adaptive for cognitive activity to occur?
SCN
- at the right time and place
time of day can also account for our _________ _______ to daily events independent of the actual event
emotional response
- scared of the dark
