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Nervous System: Unit IV > Physiology of Sleep > Flashcards

Flashcards in Physiology of Sleep Deck (11)
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Characteristics of N-REM sleep

  • Stages of sleep w/out REM (rapid eye movements)
  • involved in brain and body regeneration
  • 3 types =
    • N1
    • N2
    • N3 Slow Wave Sleep (SWS).


Characteristics of slow wave sleep

  • high amplitude slow brain waves
  • increased arousal threshold compared to wake
  • decreased muscle activity
  • slow rolling eye-movements
  • decreased heart rate, respirations and metabolism.


Characteristics of REM sleep

  • Rapid Eye Movement sleep → occurs every 90 minutes in adults.
  • EEG looks like awake EEG but arousal threshold is higher than in NREM sleep.
  • Muscles are paralyzed, except for eyes, middle ear & diaphragm. 
  • Dreams most often occur during this period, though they also occur during SWS


Physiologic response of body during REM sleep

  • active brain + paralyzed body
  • temperature regulation is suspended (poikilothermic)
    • brain temperature rises
  • engorgement of clitoris and penis
  • heart and respiration become irregular. 


NTs involved in wakefulness

  • ACH, Histamine, NE, 5HT, DA, Hypocretin
  • Hypocretin stabilizes awake and is often absent in narcolepsy.
  • Adonosine builds up in basal forebrain during wakefulness, falls with sleep.
    • Caffeine inhibits adenosine somehow.


NTs involved in sleep/wake switch

  • @ hypothalamus:
    • GABA
    • histamine
    • hypocretin
  • major role in the control of the transition from wakefulness to sleep (sleep/wake switch).


Major NTs involved in NREM sleep

  • GABA and Galanine
  • GABA and Galanine from anterior hypothalamus and elsewhere (including from thalamic reticulum) closes thalamus, synchronizes EEG, generates sleep spindles
  • Delta waves (slow-wave sleep) are thought to come from the thalamo-cortical cells and cortex.


Major NTs involved in REM sleep

  • ACh
  • low GABA and Galanine
  • DA
  • hypocretin (possible activity)   


Roles of process C & process S

  • Process C = circadian rhythm
    • Circadian alerting system is linked to core body temperature.
  • Process S = homeostatic system
    • Homeostatic system is linked to adenosine buildup @ basal forebrain



Impacts of process C/process S on wake and sleep

  • Sleepiness  waxes and wanes as the circadian alerting system interacts with the homeostatic system (process S) in 24+ hour cycles independent of sleep periods.
  • The circadian alerting system oscillates regardless of external clues
  • During wake: adenosine builds up (process S) and circadian alerting system increases (↑ body temp) increase until just before you go to sleep.


Key structures involved in wakefulness/sleep

  • basal forebrain
    • adenosine accumulate during wake, reduced during sleep
  • hypothalamus
    • sleep/wake switch
  • SCN
    • circadian clock
  • brainstem
    • ascending cortical activation
    • REM/SWS switch
  • thalamus
    • gateway of sensory info to cortex
    • generates spindles, slow wave sleep