Physiology Block 3 Week 17 18 Sleep Flashcards Preview

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Flashcards in Physiology Block 3 Week 17 18 Sleep Deck (69)
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What is sleep?

unconsciousness from which the person can be aroused by sensory or other stimuli.

Required activity

An active process involving characteristic physiological changes in the organs of the body

Highly organized sequence of events that follow a regular, cyclic program each night.


Are sleep, anesthesia, or coma the same?

They do not exhibit the same brain wave patterns characteristic of true sleep


What does sleep deprivation cause in humans?

Impairs cognition
-dec cerebral glucose utilization and blood flow

Nonspecific neural and physiological symptoms
-changes in EEG
-increased sensitivity to painful stimuli


Proposed Functions of sleep

1. Restoration and recovery of body systems as well as replenish energy stores while repairing itself after periods of energy consumption

2. To conserve energy
--metabolic rate decreases during sleep
--"sleep = energy used per day'

3. REM needed for memory consolidation, reinforcement of learning, and clearing unneeded memories

4. Required for brain development and formation of brain synapses
--high REM in newborns

5. Discharge of emotions
--dreaming in REM may provide safe discharge of emotions
--muscular paralysis prevents acting out dreams
--regions that control emotions, decision making, and social interaction reduced = relief from stress?


Do species with greater sleep times have higher or lower metabolic rates?



In humans, do sleep time and metabolic rate stay constant?

No, both decrease with age


How does sleep affect ability to retain/recall information?

humans who get plenty of NREM sleep in the first half of the night and REM sleep in the second half improve their ability to perform spatial tasks and to retain/recall information obtained the previous day


How is arousal assessed?

Electrical activity reflecting activity of neuronal populations and not the activity of individual neurons


How is the electrical activity of awake state characterized?

alpha rhythm of 8 to 13 Hz
5-100 mv wave amplitude


How is the electrical activity of sleep state characterized?

High amplitude and low frequency (0.5 to 4Hz) during stage 3 and 4 sleep

Thought to reflect a slowing and synchronous discharge of neurons.


What is delta sleep?

Deep sleep

Arousal is more difficult than stage 1 and 2, which have theta rhythm 4-7 Hz


During NREM sleep, are the muscles functional?During REM sleep?

NREM: Muscles are function, but activity is low

REM: skeletal muscle activity is absent, but heart, diaphragm, eye muscles, and smooth muscles remain functional


How is REM sleep characterized?

High frequency and low amplitude

Reflect high and desynchronized cortical activity


NREM: Somatic Activity

Few motor events

Body repositioning


REM: Somatic Activity

Paralysis (Tonic)
-post synaptic inhibition of motorneurons
-hyperpolarization of motorneuron membranes

-rapid eye movements
-muscle twitches


NREM: CNS Activation

Mean discharge rate of neurons decreased

Cerebral glucose utilization decreased overall


REM: CNS Activation

Mean discharge rate of neurons INCREASED in many regions
-PGO spikes
-Rapid Eye movements

Cerebral glucose utilization increased

Cerebral blood flow greatly increased


Hypnogram: Young Adults

Five 90 minute cycles alternating between NREM and REM sleep with brief arousals

Deepest stage of NREM occur in first part of night

Episodes of REM becomes longer as night progresses


Tonic REM sleep

Periods of sustained postural muscle atonia + bursts of eye movements


Phasic REM sleep

Postural muscle twitches


When do dreams occur?

REM sleep aka paradoxical sleep


Ultradian Rhythm

rhythm occurring within a period of less than 24 hours


Are sleep patterns of children and elderly the same as young adults?

No, they differ


What happens to total sleep time and percent REM sleep with increased age?

They decrease


REM: infants

High percent of REM sleep

The predominance of REM in infants is thought to reflect synaptic and brain development that occur at these ages.


REM: elderly

Fragmented and relatively reduced sleep time in elderly

The pattern in the elderly probably reflects a gradual deterioration with aging (as occurs in all organs) of sleep control mechanisms resulting in multiple sleep problems


What happens if sleep debt not paid? Can caffeine help?

Not meeting sleep needs still allows us to function, but motor and cognitive functions are impaired.

Caffeine cannot substitute for sleep because only counteract some of the effects of sleep deprivation.
-attenuates adenosine receptor activity promoting wakefullness


How is sleep regulated?

2 process model:

Homeostatic process
-the longer the organism is awake, the greater propensity to sleep

Circadian component
-oscillatory process that affects propensity for sleep and waking


Internal Biological Clock

26-hour period--makes us sleepy at night and awake during the day

10,000 neurouns in suprachiasmatic nucleus (SCN) of hypothalamus
-Regulates endogenous biological rhythms and is reset to match the day length by the environmental photoperiod
-mediated by photoreceptors in retina, sending signals to SCN
-pineal gland (SCN controlled) increases melatonin at night = promote sleep


What happens to sleep/wake cycle when removed from environmental cues?

the cycle is lengthened and the individual goes to bed later each night

several days later he is going to bed the same time as the first night

Cues normally maintain 24 hour sleep-wake cycle

In absence of cues, circadian clock has 26.1 hour sleep-wake cycle