Sleep Flashcards

1
Q

What are circadian rhythms?

A
  • functions that display a rhythm of about 24 hours
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2
Q

diurnal

A

active during the light

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3
Q

nocturnal

A

active during the dark

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4
Q

Rhythms may be…

A
  • behavioral,
  • physiological, or
  • biochemical
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5
Q

What generates body rhythms

A

An endogenous clock

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6
Q

What do rhythms entrain to

A

light-dark cycles

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7
Q

biological clock leads to…

A
  • precise tmiing
  • endogenous clock is not quite 24 hr
  • is entrained (set) to light/dark cycles
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8
Q

Biological clocks- rat study

A
  • When researches shift the light cycle for rats, behavior also shifts
  • with continuous dim light, behavior becomes free running
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9
Q

What allows for entrainment?

A
  • light (visual input)
  • meals
  • sleep
  • jobs/class (overnight shifts)
  • activity/exercise

several of these inputs are also regulated by the biological clock

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10
Q

What is disrupted in animals with SCN lesions?

A

circadian rhythms

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11
Q

Where is the biological clock located?

A

In the SCN- located above the optic chiasm in the hypothalamus

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12
Q

What can isolated SCN neurons do?

A
  • maintain electrical activity synchronized to the previous light cycle
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13
Q

What do most retinal ganglion cells contain, and what does this do?

A

most retinal ganglion cells contain melanopsin, a special photopigment that makes them sensitive to light

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14
Q

What does the retinohypothalmic pathway consist of?

A

retinal ganglion cells that project to the SCN

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15
Q

ganglion cells in the retinohypothalamic pathway rely on rods and cones: T/F

A

false, they DO NOT rely on rods and cones

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16
Q

Retinohypothalamic Pathway two steps

A
  1. Light causes glutamate release in SCN
  2. Synchronizes SCN neurons to each other and light/dark cycle
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17
Q

How many distinct classes of sleep are there? What are they called?

A
  • There are two distinct classes of sleep
  • Non-REM sleep and REM sleep
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18
Q

What is non-REM (NREM) sleep?

A
  • characterized by lack of rapid eye movements
  • can be divided into three stages
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19
Q

What is Rapid-eye-movement sleep (REM)?

A
  • characterized by….
  • small-amplitude, fast-EEG waves
  • no postural tension
  • rapid eye movements
20
Q

Describe the pattern of activity in an awake person

A
  • contains many frequencies
  • dominated by a mix of high frequency (15-20Hz) and low amplitude waves
  • this is known as beta activity or desynchronized EEG
21
Q

An alert, awake human’s EEG is…

A

desynchronized (aka beta activity)

22
Q

When does stage 1 sleep begin?

A

when vertex spikes appear (drowsiness)

23
Q

What are the symptoms associated w stage 1 sleep?

A
  • heart rate slows
  • muscle tension decreases
  • eyes roll about
24
Q

How long does stage 1 sleep last?

A

several minutes

25
Q

When does alpha rhythm appear? How does it appear on an EEG?

A
  • alpha rhythm appears during relaxation
  • regular oscillation at 8-12 Hz
26
Q

If a person is woken up during stage 1 or 2, how would they react?

A

the person may deny they were sleeping, even though they had failed to respond to signals

27
Q

What phenomena occur during stage 2 sleep?

A

K-complexes and sleep spindles

28
Q

What are sleep spindles? What stage of sleep are they associated with?

A
  • waves of 12-14 Hz that occur in bursts
  • looks like densely packed scribbles
  • seen in stage 2
29
Q

What are K-complexes and what stage of sleep do they appear?

A
  • sharp negative EEG potentials
  • appear in NREM 2
30
Q

When do delta waves dominate?

A

by late Stage 3 sleep

31
Q

What is another term for stage 3 sleep?

A

slow-wave sleep

32
Q

How often do delta waves occur?

A

about once per secone

33
Q

What is stage 3 sleep defined by?

A
  • the appearance of large-amplitude, very slow waves called delta waves
34
Q

What is another term for REM sleep and why is it termed that?

A
  • paradoxical sleep
  • due to the mismatch betwen brain activity that resembles an awake person and the lack of muscle activity
35
Q

What characterizes REM sleep?

A
  • active EEG w small-amplitude, high-frequency waves, like an awake person
  • muscles are relaxed- flaccid and unresponsive
36
Q

How does sleep change throughout the night?

A
  • progressive lengthening of REM sleep
  • loss of stage 3 sleep as the night goes on
37
Q

Young adult sleep

A
  • Young adults tend to be late risers
  • young adults should sleep 8 hours per night
38
Q

How does sleep change with age?

A
  • waking increases
  • REM sleep decreases more than non-REM
  • elderly often complain of insomnia
39
Q

Why do we sleep?

A
  • energy conservation
  • niche adaptation
  • body restoration
  • memory consolidation
40
Q

Why do we sleep?

Energy conservation

A

reduced…
* muscle tension
* heart rate
* blood pressure

41
Q

Why do we sleep?

Niche adaptation

A

nocturnal vs diurnal

42
Q

Why do we sleep?

body restoration

A

toxin build-up in CSF flows out of brain faster

43
Q

Why do we sleep?

Memory consolidation

A
  • sleep helps you retain information
  • neuronal activity patterns of learning are repeated during Stage 3
  • Synaptic remodeling
44
Q

Sleep regulation-basal forebrain

A
  • GABA in the basal forebrain (including hypothalamus, cortex):
  • generates NREM sleep (in particular SWS)
  • inhibits the reticular formation
  • “Electrical stimulation of the basal forebrain makes animals sleepy, while lesions of this region induce insomnia”
45
Q

Sleep regulation- reticular formation

A
  • reticular formation includes the medulla and thalamus
  • sends signals to the basal forebrain
  • promotes wakefulness
46
Q

Sleep regulation- PONS (subcoeruleus)

A
  • triggers REM by sending signals to basal forebrain
  • Inhibits motor neurons (loss of postural tension)
47
Q

Sleep regulation- Hypothalamus

A
  • hypocretin/orexin cells send information to the 3 other sleep centers
  • control switch between awake, NREM, REM (narcolepsy and sleep paralysis)
  • “Sends axons to the other three sleep centers and seems to coordinate them, enforcing the patterns of sleep. Loss of hypocretin can lead to disorganized sleep, such as REM- like muscle atonia while still awake (in narcolepsy)