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Round 1 Flashcards

1
Q

The body has various clocks that also need to be synchronized by a…

A

master clock (suprachiasmatic nucleus)

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2
Q

clocks can control…

A

body temp, heart rate, respiration, sleep/wake, digestive, hormones, etc

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3
Q

the master clock

A

SCN (suprachiasmatic nucleus)

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4
Q

where is the SCN?

A

hypothalamus

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5
Q

property of SCN cells

A

intrinsic rhythm from ‘clock genes’ (~24h rhythm of activity)

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6
Q

how does SCN synchronize all the other clocks

A

sends out signals to set the cycle of peak activity and rest

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7
Q

SCN also sends signals to?

A

Arousal System - in the brainstem and forebrain

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8
Q

SCN also determines..

A

arousal and alertness

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9
Q

SCN’s rhythm can be entrained by..

A

light - its 24h rhythm can be entrained to day/night cycle

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10
Q

arousal is peak during?

A

day

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11
Q

sleepiness is timed to occur..

A

later in the day and night

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12
Q

what does the SCN set?

A

circadian rhythm

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13
Q

2 main elements of circadian rhythm

A

1) SCN - synchronizer, 2) pineal gland - melatonin

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14
Q

circadian rhythm regulates..

A

sleep patterns, feeding patterns, core body temp, brain wave activity, cell regeneration, hormone production, etc

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15
Q

circadian rhythm controls..

A

the timing of sleep

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16
Q

circadian rhythm is independent of…

A

previous amount of sleep or wakefulness

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17
Q

long sleep can be..

A

ineffective if it happens at the wrong time - like peak arousal

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18
Q

circadian rhythms are…

A

endogenously generated by SCN

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19
Q

circadian rhythmic activities are controlled by..

A

a local clock that has its own 24h rhythm, synced by SCN (which is synced by light)

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20
Q

adults - peak sleepiness

A

2 - 4 am and 1-3 pm

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21
Q

adults - arousal increases again after

A

afternoon dip to late evening

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22
Q

dips in sleepiness/arousal

A

vary depending if you are morning/evening person

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23
Q

sleepiness dips are less intense if..?

A

we have had enough sleep

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24
Q

circadian rhythms across ppl

A

vary slightly, between 23.5 - 24.5hrs (24.2 mean)

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25
25% of ppl have a circadian period...
slightly less than 24 hrs
26
75% ppl have a circadian period...
slightly more than 24 hrs
27
(circadian) exact intrinsic value depends on..
structure of genes for circadian rhythm
28
closely related people like twins show..
highly similar sleep patterns
29
there are more night/morning people
night ppl
30
genes involved in sleep
PER1, PER2, PER3, CRY1, CRY2, CLOCK, BMAL
31
mutations in PER gene
shorten, lengthen or abolish circadian rhythm period
32
ultradian rhythms
cycle repeated throughout 24hrs, e.g. Rest-Activity Cycle
33
infradian rhythm
rhythm period longer than circadian, e.g. menstruation
34
SCN controls...
timing of sleep/wake cycle, promotes arousal, REM
35
SCN cycle length
24 hrs +/- 11 mins
36
total SCN neurons
about 20,000
37
dorsomedial SCN (top)
~24 hr rhythm that persists under constant darkness
38
ventrolateral SCN (bottom)
neurons that receive direct retinal input to entrain to day/night
39
lesions to SCN
abolish free-running rhythms (non-environment)
40
isolated SCN
continue to cycle
41
transplanted SCN
gives rhythm of donor
42
max rate of AP from SCN
mid day
43
night time rate of AP in SCN
decreases (falls)
44
zeitgebers
external cues (SCN entrain to local enviro by them)
45
examples of zeitgebers
temp, sunlight
46
melatonin
hormone released from pineal gland, endo. synchronizer that stabilizes and reinforces circadian rhythms
47
most powerful zeitgeber
light
48
SCN neurons excitatory neurotransmitters
glutamate, PACAP (activate SCN, cause changes in expression of clock genes in SCN cells)
49
how does light entrain SCN?
through special retinal ganglion cells (RGCs) that have light-absorbing pigment melanopsin
50
melanopsin
light-absorbing pigment in ipRGCs
51
ipRGC (intrinsically-photosensitive)
photoreceptor cells send axons to SCN through retino-hypothalamic tract
52
ipRGCs most sensitive to..
absorption of short-wavelength (high frequency) blue light
53
other zeitgebers
when you eat, exercise, meds
54
melatonin tablets
doesn't have strong entrainment effect
55
pineal gland (contributes to circadian rhythm and sleep-wave cycle)
produces and releases melatonin (behind thalamus)
56
features of melatonin secretion
sleep is least likely to occur before secretion, happens at night (with robust CR), start of secretion and increase in sleepiness occurs 2hrs before regular bedtime, max levels in blood during 3-4am
57
release of melatonin is regulated by...
SCN
58
SCN (inhibits) delays the release of melatonin until what decreases?
light levels in the evening
59
melatonin levels rise only after...
dark (little variation, around 9pm, increase till 2-3am, low levels at 7 - 8am)
60
2 melatonin effects on sleep-wake cycle
1) entrains and shifts circadian rhythm through its release, 2) promotes sleep in sleep-inducing way by increasing homeostatic drive to sleep
61
melatonin production is inhibited by..
light (but light activates SCN neurons)
62
period of sleep/wake
24.2hrs (23.8 - 27.1hrs, genetically determined)
63
max sleepiness
core body temp at lowest, melatonin levels at highest
64
newborns 0-3 months
14 - 17 hours
65
infants 4-11 months
12-15 hrs
66
toddlers 1-2 yrs
11-14hrs
67
preschoolers 3-5 yrs
10-13 hrss
68
children 6-13 yrs
9 - 11 hrs
69
teenagers 14-17 hrs
8 - 10 hrs
70
young adults/adults 18-64yrs
7-9 hrs
71
older adults 65+ yrs
7-8 hours
72
purpose of sleep-wake homeostatic mechnaism
to enter deep non-REM sleep (slow-wave)
73
EEG
electroencephalogram
74
NREM stages
Stage 1, Stage 2, Stage 3
75
Stage 1 NREM
light sleep, eyes move slowly, heart and breathing rates begin to slow
76
Stage 2 NREM
(half the night in this stage) slower brain waves with occasional bursts of rapid waves
77
Stage 3 NREM
even slower brain waves, slow delta waves (high voltage) account for 20% of brain activity in EEG, difficult to awaken from
78
REM components
tonic and phasic
79
phasic REM
sympathetic state, rapid eye movements, muscle twitches, respiratory variability
80
tonic REM
parasympathetic state, no eye movements
81
length of NREM sleep in first phase of sleep
70-100 mins
82
when do you enter REM sleep?
1-1.5 hours after falling asleep
83
what percent of your sleep is NREM 1
5%
84
what percent of your sleep is NREM 3
20%
85
what percent of your sleep is REM
25%
86
how long might first REM be?
less than 10 mins
87
synaptic type signalling
only by neurons, short distances, uses neurotransmitters
88
non-synaptic signalling
neurons and non-neurons, hormonal (long/very long) or local chemical mediators (paracrine (short, adjacent), autocrine (very short, self))
89
water soluble chemical
synaptic + nos-synaptic, neurotransmitters, local chemical mediators, most hormones, growth factors, cytokines, short survival, short to long lasting effects
90
lipid soluble
non-synaptic, steroid, thyroid, retinoid hormones, vitamin D, long survival, long lasting effects
91
receptors for water soluble
membrane-bound, receptors that form ion channels, receptors linked to G proteins, receptors linked to tyrosine kinase
92
receptors for lipid soluble
intracellular, receptors that bind to DNA
93
Gamma-amino-butyric acid (GABA)
inhibitory transmitter
94
benzodiazepines (BZD)
enhances GABA's inhibition at same time as GABA, cause channel pore to open wider
95
barbiturates
another enhancer for GABA inhibition
96

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