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Brainbee > Round 1 > Flashcards

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
Q

25% of ppl have a circadian period…

A

slightly less than 24 hrs

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26
Q

75% ppl have a circadian period…

A

slightly more than 24 hrs

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27
Q

(circadian) exact intrinsic value depends on..

A

structure of genes for circadian rhythm

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28
Q

closely related people like twins show..

A

highly similar sleep patterns

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29
Q

there are more night/morning people

A

night ppl

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30
Q

genes involved in sleep

A

PER1, PER2, PER3, CRY1, CRY2, CLOCK, BMAL

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31
Q

mutations in PER gene

A

shorten, lengthen or abolish circadian rhythm period

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32
Q

ultradian rhythms

A

cycle repeated throughout 24hrs, e.g. Rest-Activity Cycle

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33
Q

infradian rhythm

A

rhythm period longer than circadian, e.g. menstruation

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34
Q

SCN controls…

A

timing of sleep/wake cycle, promotes arousal, REM

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35
Q

SCN cycle length

A

24 hrs +/- 11 mins

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36
Q

total SCN neurons

A

about 20,000

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37
Q

dorsomedial SCN (top)

A

~24 hr rhythm that persists under constant darkness

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38
Q

ventrolateral SCN (bottom)

A

neurons that receive direct retinal input to entrain to day/night

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39
Q

lesions to SCN

A

abolish free-running rhythms (non-environment)

40
Q

isolated SCN

A

continue to cycle

41
Q

transplanted SCN

A

gives rhythm of donor

42
Q

max rate of AP from SCN

A

mid day

43
Q

night time rate of AP in SCN

A

decreases (falls)

44
Q

zeitgebers

A

external cues (SCN entrain to local enviro by them)

45
Q

examples of zeitgebers

A

temp, sunlight

46
Q

melatonin

A

hormone released from pineal gland, endo. synchronizer that stabilizes and reinforces circadian rhythms

47
Q

most powerful zeitgeber

A

light

48
Q

SCN neurons excitatory neurotransmitters

A

glutamate, PACAP (activate SCN, cause changes in expression of clock genes in SCN cells)

49
Q

how does light entrain SCN?

A

through special retinal ganglion cells (RGCs) that have light-absorbing pigment melanopsin

50
Q

melanopsin

A

light-absorbing pigment in ipRGCs

51
Q

ipRGC (intrinsically-photosensitive)

A

photoreceptor cells send axons to SCN through retino-hypothalamic tract

52
Q

ipRGCs most sensitive to..

A

absorption of short-wavelength (high frequency) blue light

53
Q

other zeitgebers

A

when you eat, exercise, meds

54
Q

melatonin tablets

A

doesn’t have strong entrainment effect

55
Q

pineal gland (contributes to circadian rhythm and sleep-wave cycle)

A

produces and releases melatonin (behind thalamus)

56
Q

features of melatonin secretion

A

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
Q

release of melatonin is regulated by…

A

SCN

58
Q

SCN (inhibits) delays the release of melatonin until what decreases?

A

light levels in the evening

59
Q

melatonin levels rise only after…

A

dark (little variation, around 9pm, increase till 2-3am, low levels at 7 - 8am)

60
Q

2 melatonin effects on sleep-wake cycle

A

1) entrains and shifts circadian rhythm through its release, 2) promotes sleep in sleep-inducing way by increasing homeostatic drive to sleep

61
Q

melatonin production is inhibited by..

A

light (but light activates SCN neurons)

62
Q

period of sleep/wake

A

24.2hrs (23.8 - 27.1hrs, genetically determined)

63
Q

max sleepiness

A

core body temp at lowest, melatonin levels at highest

64
Q

newborns 0-3 months

A

14 - 17 hours

65
Q

infants 4-11 months

A

12-15 hrs

66
Q

toddlers 1-2 yrs

A

11-14hrs

67
Q

preschoolers 3-5 yrs

A

10-13 hrss

68
Q

children 6-13 yrs

A

9 - 11 hrs

69
Q

teenagers 14-17 hrs

A

8 - 10 hrs

70
Q

young adults/adults 18-64yrs

A

7-9 hrs

71
Q

older adults 65+ yrs

A

7-8 hours

72
Q

purpose of sleep-wake homeostatic mechnaism

A

to enter deep non-REM sleep (slow-wave)

73
Q

EEG

A

electroencephalogram

74
Q

NREM stages

A

Stage 1, Stage 2, Stage 3

75
Q

Stage 1 NREM

A

light sleep, eyes move slowly, heart and breathing rates begin to slow

76
Q

Stage 2 NREM

A

(half the night in this stage) slower brain waves with occasional bursts of rapid waves

77
Q

Stage 3 NREM

A

even slower brain waves, slow delta waves (high voltage) account for 20% of brain activity in EEG, difficult to awaken from

78
Q

REM components

A

tonic and phasic

79
Q

phasic REM

A

sympathetic state, rapid eye movements, muscle twitches, respiratory variability

80
Q

tonic REM

A

parasympathetic state, no eye movements

81
Q

length of NREM sleep in first phase of sleep

A

70-100 mins

82
Q

when do you enter REM sleep?

A

1-1.5 hours after falling asleep

83
Q

what percent of your sleep is NREM 1

A

5%

84
Q

what percent of your sleep is NREM 3

A

20%

85
Q

what percent of your sleep is REM

A

25%

86
Q

how long might first REM be?

A

less than 10 mins

87
Q

synaptic type signalling

A

only by neurons, short distances, uses neurotransmitters

88
Q

non-synaptic signalling

A

neurons and non-neurons, hormonal (long/very long) or local chemical mediators (paracrine (short, adjacent), autocrine (very short, self))

89
Q

water soluble chemical

A

synaptic + nos-synaptic, neurotransmitters, local chemical mediators, most hormones, growth factors, cytokines, short survival, short to long lasting effects

90
Q

lipid soluble

A

non-synaptic, steroid, thyroid, retinoid hormones, vitamin D, long survival, long lasting effects

91
Q

receptors for water soluble

A

membrane-bound, receptors that form ion channels, receptors linked to G proteins, receptors linked to tyrosine kinase

92
Q

receptors for lipid soluble

A

intracellular, receptors that bind to DNA

93
Q

Gamma-amino-butyric acid (GABA)

A

inhibitory transmitter

94
Q

benzodiazepines (BZD)

A

enhances GABA’s inhibition at same time as GABA, cause channel pore to open wider

95
Q

barbiturates

A

another enhancer for GABA inhibition

96
Q
A

Brainbee (1 decks)

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