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Physio: 5# Arousal Mechanisms, Consciousness, & Sleep
Q1. Sleep is best defined as:
Complete absence of cortical activity
Loss of consciousness that cannot be reversed
Unconsciousness from which a person can be aroused by stimuli
Suppression of the reticular activating system
Explanation:
Sleep is a reversible state of unconsciousness, unlike coma which is not arousable.
Q2. Which structure is MOST critical for transitions between sleep and wakefulness?
Basal ganglia
Cerebellum
Primary motor cortex
Brainstem and hypothalamic nuclei
Explanation:
Nuclei in the brainstem and hypothalamus regulate circadian transitions between sleep and wakefulness.
Q3. REM sleep is also known as:
Paradoxical or desynchronized sleep
Slow-wave sleep
Dreamless sleep
Delta sleep
Explanation:
REM sleep shows EEG patterns similar to wakefulness despite true sleep, hence “paradoxical.”
Q4. REM sleep in young adults typically occurs:
Only during early night sleep
Every 90 minutes
Only once per night
Exclusively before awakening
Explanation:
REM sleep appears cyclically about every 90 minutes and occupies ~25% of total sleep.
Q5. Which feature is characteristic of REM sleep?
High muscle tone
Low brain metabolism
Regular heart rate
Marked depression of skeletal muscle tone
Explanation:
REM sleep shows profound muscle atonia due to inhibition of spinal motor neurons.
Q6. EEG during REM sleep most closely resembles:
Wakefulness EEG
Stage 4 NREM sleep
Theta rhythm
Delta rhythm
Explanation:
REM sleep shows desynchronized EEG similar to the awake state.
Q7. Which statement about NREM sleep is TRUE?
Brain metabolism increases by 20%
Muscle tone is absent
Blood pressure and metabolic rate decrease
EEG resembles wakefulness
Explanation:
NREM sleep is associated with reduced BP, RR, and basal metabolic rate.
Q8. Sleep spindles and K-complexes are characteristic of:
Stage 1 NREM sleep
Stage 2 NREM sleep
Stage 3 NREM sleep
REM sleep
Explanation:
Stage 2 NREM sleep shows sleep spindles (12–14 Hz) and K-complexes.
Q9. The largest event in a healthy human EEG is the:
Alpha wave
Beta wave
Delta wave
K-complex
Explanation:
K-complexes are high-voltage biphasic waves and the largest normal EEG events.
Q10. Delta waves during wakefulness indicate:
Brain dysfunction
Normal relaxation
Focused attention
Normal aging
Explanation:
Delta and theta waves during wakefulness suggest pathological brain states.
Q11. Alpha waves are most prominent when a person is:
In deep sleep
Emotionally stressed
Awake, relaxed, with eyes closed
Performing mental arithmetic
Explanation:
Alpha waves (8–13 Hz) dominate during quiet wakefulness with closed eyes.
Q12. Alpha block refers to:
Transition from REM to NREM sleep
Replacement of alpha waves by beta waves during attention
Suppression of gamma oscillations
Appearance of delta waves
Explanation:
Sensory stimulation or mental concentration abolishes alpha rhythm, producing beta activity.
Q13. Damage to the reticular formation most likely causes:
Insomnia
REM sleep behavior disorder
Narcolepsy
Coma
Explanation:
The reticular formation is essential for arousal; its damage results in coma.
Q14. Which neurotransmitter is released by locus coeruleus neurons?
Norepinephrine
Acetylcholine
GABA
Histamine
Explanation:
The locus coeruleus is the major noradrenergic nucleus of the brain.
Q15. Which neurotransmitter predominates during REM sleep?
Serotonin
Norepinephrine
Acetylcholine
Histamine
Explanation:
REM sleep is characterized by dominant cholinergic (acetylcholine) activity.
Q16. Increased GABA release is most characteristic of:
Wakefulness
NREM sleep
REM sleep
Focused attention
Explanation:
NREM sleep shows increased GABAergic inhibition and reduced histamine release.
Q17. Which substance accumulates during prolonged wakefulness and induces sleep?
Dopamine
Serotonin
Histamine
Muramyl peptide
Explanation:
Muramyl peptide accumulates in CSF and induces natural sleep when injected.
Q18. Activation of low-threshold T-type Ca²⁺ channels in the thalamus contributes to:
Thalamocortical synchrony during sleep
REM atonia
Alpha block
Gamma oscillations
Explanation:
These channels generate synchronized thalamocortical rhythms seen in sleep.
Q19. Melatonin secretion is highest:
During daylight hours
During REM sleep only
During the dark period of the day
During focused attention
Explanation:
Melatonin is secreted at night and provides a timing signal for circadian rhythms.
Q20. One important physiological function of sleep is:
Increased sympathetic tone
Clearance of metabolic waste products
Suppression of memory formation
Permanent cortical inhibition
Explanation:
Sleep restores brain homeostasis, cognition, and clears metabolic waste.