Arousal and sleep Flashcards
name the device used to measure electrical activity in the brain
Electroencephalogram
name the 4 types of waves observed in electroencephalogram
beta waves
alpha waves
theta waves
delta
describe each type of wave and state when it occurs
1)beta waves: lowest amplitude and highest frequency (14-30Hz) person should be awake and focused
2)alpha waves: have a higher amplitude and a lower frequency(8-13Hz) person should be lying relaxed with eyes closed
3)theta waves: have even a higher amplitude and lower frequency (4-7Hz) person is in light sleep
4)delta waves:highest amplitude and lowest frequency (0.5-3Hz) person is in deep sleep
define sleep
its the loss of consciousness from which a subject can be awakened by appropriate stimuli
name the device used for sleep study
polysomnography
describe Non-REM sleep (slow wave-dreamless)
this sleep have synchronised waves waves with high amplitude and low frequency, dreams can occur but cant be recalled and this sleep is divided into 4 stages
1&2 are light sleep - 3&4 are deep sleep
describe the first stage of Non-REM sleep
it’s the initial stage between awakening and sleeping. person feels relaxed with their eyes closed. EEG shows diminishing of alpha waves and appearance of theta waves
describe the second stage of Non-REM sleep
its light sleep stage that have theta waves in addition to sleep spindle and k complex both help maintain your sleeping
describe the third stage of Non-REM sleep
its moderately deep sleep shows delta waves and occurs after 20-25minutes after beginning of sleep
describe the fourth and last stage of Non-REM sleep
deep sleep person becomes fully relaxes and eeg is dominated by delta waves
what adjustments happen in the body during Non-REM sleep
1)peripheral vascular tone decreases
2)heart rate decreases
3)respiratory rate decreases
4)basal metabolic rate decreases
5) growth Hormone decreases
describe REM sleep
have desynchronized EEG waves showing beta waves during sleep. it has rapid eye movement and dream and shows complete muscle paralysis.
it lasts for 5-30 minutes and occurs every 90minutes. its a type of sleep where brain activity is very active.
what adjustments happen in the body during REM sleep
1)muscle tone decreases
2)brain metabolism increases
3) heart rate increases
4) breathing becomes rapid, irregular and shallow
5)autonomic reaction (penile erection)
6) decrease in homeostatic response
describe the pathway of arousal in details
firstly the pontine reticular formation sends ascending fibres carrying acetylcholine to the thalamic relay nuclei then these fibres continues to ascend until reaching the cerebral cortex causing wide spreading cortical activity this is called the reticular activation system
locus ceruleus is a nucleus of the brain stem that secrets norepinephrine that helps in arousal
posterior hypothalamus secrets histamine that also helps in arousal
lateral hypothalamus secrets orexin that adjust sleep time to be during night time and not day time
how does orexin levels affect arousal and sleep
when orexin levels are high they favour arousal but when levels decrease it favours sleep
what is narcolepsy?
it occurs when the nerve fibres of the lateral hypothalamus are destroyed and levels of orexin are abnormal its characterized by sudden attacks of sleep
describe the pathway of sleep in details
medullary reticular formation and anterior hypothalamus(ventrolateral preoptic area) they both send inhibitory neurotransmitters(GABA&Galanine to the arousal centers inhibiting them and initiating sleep
whats the relationship between sleep and levels of serotonin?
serotonin is released from raphe nuclei and when its levels increases the initiation of sleep increases
pathway of REM sleep
its called the pontogeniculo occipital pathway where the electrical activity originate in the pons and travels to the geniculate nucleus then to the visual/occipital cortex.
physiological importance of sleep
1)neural maturation
2)facilitation of learning and memory
3)cognition
4)conservation of metabolic energy
5)clearance of metabolic waste products
adenosine and arousal
when adenosine levels increase it causes the inhibition of neurones that inhibit the VLPA pathway therefore the VLPA pathway is active and sleep is being promoted. caffeine blocks the adenosine receptors.
melatonin and sleep
melatonin is secreated from the pineal glands which makes you sleepy when melatonin levels increases
interleukin 1 and sleep
increases in the csf of the brain during sleep
