Arousal and sleep

Question 1

name the device used to measure electrical activity in the brain

Answer 1

Electroencephalogram

Question 2

name the 4 types of waves observed in electroencephalogram

Answer 2

beta waves
alpha waves
theta waves
delta

Question 3

describe each type of wave and state when it occurs

Answer 3

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

Question 4

define sleep

Answer 4

its the loss of consciousness from which a subject can be awakened by appropriate stimuli

Question 5

name the device used for sleep study

Answer 5

polysomnography

Question 6

describe Non-REM sleep (slow wave-dreamless)

Answer 6

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

Question 7

describe the first stage of Non-REM sleep

Answer 7

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

Question 8

describe the second stage of Non-REM sleep

Answer 8

its light sleep stage that have theta waves in addition to sleep spindle and k complex both help maintain your sleeping

Question 9

describe the third stage of Non-REM sleep

Answer 9

its moderately deep sleep shows delta waves and occurs after 20-25minutes after beginning of sleep

Question 10

describe the fourth and last stage of Non-REM sleep

Answer 10

deep sleep person becomes fully relaxes and eeg is dominated by delta waves

Question 11

what adjustments happen in the body during Non-REM sleep

Answer 11

1)peripheral vascular tone decreases
2)heart rate decreases
3)respiratory rate decreases
4)basal metabolic rate decreases
5) growth Hormone decreases

Question 12

describe REM sleep

Answer 12

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.

Question 13

what adjustments happen in the body during REM sleep

Answer 13

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

Question 14

describe the pathway of arousal in details

Answer 14

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

Question 15

how does orexin levels affect arousal and sleep

Answer 15

when orexin levels are high they favour arousal but when levels decrease it favours sleep

Question 16

what is narcolepsy?

Answer 16

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

Question 17

describe the pathway of sleep in details

Answer 17

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

Question 18

whats the relationship between sleep and levels of serotonin?

Answer 18

serotonin is released from raphe nuclei and when its levels increases the initiation of sleep increases

Question 19

pathway of REM sleep

Answer 19

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.

Question 20

physiological importance of sleep

Answer 20

1)neural maturation
2)facilitation of learning and memory
3)cognition
4)conservation of metabolic energy
5)clearance of metabolic waste products

Question 21

adenosine and arousal

Answer 21

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.

Question 22

melatonin and sleep

Answer 22

melatonin is secreated from the pineal glands which makes you sleepy when melatonin levels increases

Question 23

interleukin 1 and sleep

Answer 23

increases in the csf of the brain during sleep