W9 - Sleep & Wakefulness Flashcards
Endogenous cycles
generated within the body regardless of environment
-circadian rhythms, temperature, sleep-wakefulness, mood
Biological clock
mechanism that generates endogenous cycle
-cycle maintained despite medication, loss of homeostasis, most brain damage
Free running rhythm
reset (entrained) by light, the main time giver
Supra Chiasmatic Nucleus (SCN)
part of the hypothalamus, sets circadian rhythm
- receives input via axons of the retinohypothalamic pathway (retina to hypothalamus)
- damage results in less constant cycles and failure to entrain light cues
Per ad Tim genes
the genes are activated by low levels of protein, inhibited by high levels of protein
What regulates the pineal gland
SCN.
- Pineal gland releases melatonin 2 hrs prior to sleep
- has inhibitory effect on reticular formation
Reticular formation
midbrain structure extending from medulla to forebrain.
Sends axons up to the brain and down to the spinal cord.
Potomesencephalon
maintains arousal in wife regions of the cerebral cortex
-inhibits muscle during REM sleep
Locus coeruleus
Active in response to meaningful events
- enhances response to important info/events
- inactive in sleep
Hypothalamus in terms of wakefulness
- releases histamine which stimulates arousal
- antihistamine cross blood brain barrier and cause drowsiness
Orexin
releases of orexin maintains arousal, lack of orexin results in sleep
Dorsal Raphe
promotes wakefulness via excitatory pathways
inhibits sleep via inhibitory pathways
Two mechanisms of getting to sleep
- Active process: SCN triggers malatonin production
- inhibition of arousal, decrease body temp - Passive build up of ‘sleep pressure’
- adenosine
- prostaglandins
Adenosine
accumulates during the day, produces sleepiness
- declines during sleep
- inhibited by coffee
Prostaglandins
accumulates during the day, promotes sleep
- declines during sleep
- inhibits hypothalamic cells that raise arousal
