Sleep and Biological Rhythms (Ch.14) Flashcards

1
Q

Types of “Circa Rhythms”

A
  1. Circatidal (12 hrs)
  2. Circadian (24 hrs)
  3. Circalunar (30days)
  4. Circannual (one year)
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2
Q

Period:

A

The time interval separating one peak or trough from the next in a repeating cycle

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3
Q

Zeitgeber:

A

Time giver

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4
Q
  1. Circadian Rhythms (reoccurring naturally on a 24 hour clock) slightly are the result of an
A

Endogenous clock (a clock from within)

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5
Q

Daily Rhythms persist in..

A

constant conditions

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6
Q

Rythms develop normally in the absence of…

A

external cycles (innate)

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7
Q

Tau:

A
  • Tau varies across and within species in the same environment
  • Tau can be selected by breeding altered by gene mutations and eliminated by gene knockouts
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8
Q

Jean deMairan 1729 identified the first circadian rhythm in the Mimosa Plant using …

A

temporal isolation

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9
Q
  1. Adaptive Significance of Circadian clocks: External coordination and anticipation to:
A
  • Geographic Stimuli (light, temp)

- Biological stimuli (food resources, predators, mates)

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10
Q

Do circadian clocks contribute to fitness in Natural Habitats?

A

-SCN ablated animals were in burrows at night however they were active which increase their predation

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11
Q

Entrainment phase

A

Animals display different endogenous(originating from within) periods that don’t exactly match the environmental light dark cycle

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12
Q

Entrainment Hypothesis

A

Entrainment is achieved by daily adjustment of rhythm phase, to offset the difference between τ and T.

  • Squirles see light for only a few seconds every 3 to 4 days
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13
Q

Retinohypothalmic Tract:

A
  • Intrinsically photosensitive retinal ganglion cells

- Axons that make up the RHT do not originate from rods and cones

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14
Q

Entrainment Pathway

A
  • Light enters the eyes through the rods and cones and Speacialized ganglion cells (containing melanopsin)
  • Then go through the Retinohypothalaamic tract to thalamus to form the vision
    (END OF ENTRAINMENT)
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15
Q

Evidence that the SCN are an endogenous circadian clock

A
  • Lesions of the SCN eliminate rhythmicity
  • Electrical or chemical stimulation of the SCN induces phase shifts
  • SCN neurons oscillate (move back and forth at a normal speed)
  • SCN transplants can restore rhythms after SCN lessons (with the period of the donor)
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16
Q

What other Stimuli contribute to entrainment besides light?

A
  • Arousal
  • Exercise
  • Drugs
  • > these stimuli exert their influences on the SCN via another neural pathway
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17
Q

Chronotype: Night owls and early birds

A

-Between ages 10 and 40 men tend to be later risers than females

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18
Q

Why Study Circadian Rhythms?: Human Performanc and Societal cost

A

Physical and cognitive capacities vary throughout the day (shift work, travel, education, sports)

  • Need of job, demand for services (firefighter)
  • Problemed areas: performance and productivity, safety, health
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19
Q

Why Study Circadian Rhythms?: Medicine

A

Rhythms are important for both diagnosis and treatment

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20
Q

Why Study Circadian Rhythms?: Psychopathology

A

Disruption of circadian timing implicated in sleep and affective disorders

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21
Q

Shift work and Productivity

A
  • The greater you work the greater your output, BUT for many jobs productivity per hour of work is lower on 10-12 compared to 8
  • Leads to increased risk of accident
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22
Q

Health Problems of Shift Workers

A
  • Sleep and Vigilance
  • Cardiovascular System (50% increase in risk - increases with years of exposure to shift work)
  • Gastrointestinal System - Significant increase for GI disease (e.g. ulcers)
  • Hormonal and reproductive system
  • Anxiety, depression, substance use
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23
Q

Circadian windows of vulnerability

A
  • Heart attacks and strokes more likely in the morning

- Asthma attacks and strokes more likely in the evening

24
Q

Circadian disruption underlying disease processes

A
  • Do circadian disorders cause other disorders (concerns about circadian disruption and cancer vulnerability)
25
Q

Circadian Rhythms in treatment efficacy

A

An effective dose at one time of day may be ineffective at another time

26
Q

Circadian Rhythms in baseline function

A

You need to know circadian variation to know what is normal for a given time of day (eg. temp and fever)

27
Q

3 Methods used for Examining Sleep States

A
  • Electrical brain potentials can be used to classify levels of arousal and states of sleep
    1. Electroencephalography (EEG)
    2. Elector-oculography (EOG)
    3. Electromyography (EMG)
28
Q
  1. Electroencephalography (EEG)
A

-Records electrical activity in the brain

29
Q
  1. Electro-oculography (EOG)
A
  • Records eye movements
30
Q

Electromyography (EMG)

A
  • Records muscle activity
31
Q

2 Distinct Classes of Sleep:

A
  1. Non-rapid eye movement sleep (NREM)

2. Rapid eye movement sleep (REM)

32
Q
  1. NREM
A
  • Can be divided into 4 stages, 3 and 4 of NREM sleep are characterized by slow wave EEG activity
  • Parasympathetic autonomic profile
  • Metabolism and neural activity reduced
  • Respiration slow, regular
33
Q
  1. REM
A
  • Characterized by small amplitude, fast EEG waves, no postural tension, and rapid eye movements
  • Sympathetic autonomic profile
  • Metabolism and neural activity increased; phasic PGO waves
  • Respiration irregular, cardiovascular tone increased
  • Dreaming
34
Q

How Many stages are there of Slow Wave Sleep?

A

4

35
Q

1st stage of Slow Wave Sleep

A
  • Show events of irregular frequency and similar amplitude as well as Vertex Spikes or sharp waves
  • Heart rate slows, muscle tension reduces, eyes move about
  • Lats several minutes
36
Q

2nd stage of Slow Wave Sleep

A
  • Defined by waves of 12 to 14 Hz that occur in bursts, called sleep spindles
  • K complexes appear - sharp negative EEG potentials
37
Q

3rd stage of Slow Wave Sleep

A
  • Defined by the appearance of large amplitude, very slow waves called delta waves (slow wave sleep)
  • Delta waves occur about once per second
38
Q

4th stage of Slow Wave Sleep

A
  • Delta waves are at least half of the time

- REM sleep follows

39
Q

In a typical night of a young adult sleep:

A
  • Sleep time 7-8 hr
  • 45 to 50% is stage 2 NREM sleep
  • 20% is REM sleep
  • Cycles last 90-100 min
  • Cycles early in the night have more stage 3 and stage 4 SWS, and later cycles have more REM sleep
40
Q

Sleep Changes Across the lifespan

A

REM gets a lot shorter

41
Q

Sleep in Marine Animals

A
  • Some marine animals show different sleep stages on land
  • e.g: Seal - Unihemispheric NREM sleep in water
  • Bilateral NREM and REM sleep on land
42
Q

Consequences of sleep deprivation in humans:

A
  • Slow reaction time (16h SD equivalent to legal alcohol intoxication)
  • Irritability
    Lapse in concentration
  • hallucinations (multiple days)
  • fatal familial insomnia
43
Q

Consequences of sleep deprivation in animals:

A
  • Longterm: characterized by a metabolic syndrome that leads to death
44
Q

Energy Conservation (Biological Functions of Sleep)

A
  • Decrease in required metabolic (chemical process that occurs and maintains life) energy
  • > Metabolic activity in the brain is decreased
45
Q

Avoid Predation (Biological Functions of Sleep)

A

Temporal niches of predator and prey

46
Q

Body Restoration (Biological Functions of Sleep)

A

Recovery from illness

  • Evidence: Sleep inhibits immune function
  • More sensitive to pain
  • More likely to develop diabetes
  • More likely to develop cancer
47
Q

Memory Consolidation (Biological Functions of Sleep)

A

Performance on learning task is better if training and testing is separated by a sleep bout
- Sleep aids memory consolidation: some parts more than other

48
Q

Sleep enforces niche adaptation:

A
  • Each species physiology is specifically adapted to a particular time of day
  • Humans are diurnal (example: eyes adapted for daylight conditions
  • Bats: are nocturnal. (example: echolocation)
  • Sleep is for aligning wake and sleep to the appropriate time of day to avoid falling prey
49
Q

What generates slow wave sleep?

A

the forebrain

50
Q

Bremer:

A

Isolated brain (encephala isle) vs isolated forebrain (cerveau isle)

51
Q

The basal forebrain receives ______ signals from the ___________ nucleus of the hypothalamus

A
  • GABAergic
  • tuberomammilarary

THEREFOR the basal forebrain promotes NREM sleep due to GABA release from the TMN
- Left alone this system would leave the brain engages in NREM indefinitely

52
Q

The _____ formation wakes up the forebrain

A

reticular

  • The reticular formation is a diffuse network of cells extending from the medulla to the thalamus
  • Stimulation in the reticule activating system in sleeping animals wakes them up
  • Lesision of the reticular activating system induces indefinite sleep (coma)
53
Q

The ____ trigger REM sleep

A

Pons

  • LEsision just lateral to the locus coeruleus abolish REM
  • Simulation sot the same region can induce prolonged REM
54
Q

During REM sleep…

A
  • Motorneurons are inhibited - loss of muscle tone (which requires the LC as lesions result in a lack of inhibition)
55
Q

A hypothalamic sleep center

A

The lateral hypothalamus contains neurons that synthesize hypocretin (orexin)

  • These hypocretin neurons project to:
    1. The basal forebrain
    2. the reticular formation
    3. the locus coerules
    4. Tuberomammilary nucleus
56
Q

Narcolepsy

A

Sudden Day time sleep

  • Patients suffer from rapid REM onset and excessive daytime sleepiness
  • Patients have suffered from about 90% of heir hypocretin neurons
  • hypocretin Inhibits sleep and prevents the transition from wake to REM