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26 Cards in this Set
- Front
- Back
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Circadian Rhythm
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-Cycles of light & dark influence us
-Requires resetting (external cues) -Rhythms are Not astronomical but Are biological Built In Clock: -sleep wake cycle -digestion -kidney function -hormone secretion -BP - body temp During Sleep: Resources diverted to body repair, maintenance, & memory consolidation --Internal Clocks=Just short of 25hours |
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Circadian Rhythm
2 Findings |
1) Need external Cues-keep us on track
2) Rhythms are adjustable-1wk to shift circadian rhythm |
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Locus of Clock
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Suprachiasmatic Nucleus (SCN)
-hypothalamus above optic nerves -Receives light levels--Retino-hypothalamic pathway -Removal abolishes rhythm of sleep and waking |
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How The SCN Keeps Time
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1)Separate SCN neurons in a tissue culture dish
2)Rhythms remain for firing rate, clucose utilization & protein synthesis 3)Rhythm does not remain for light-dark cycles (input from eyes is necessary) --Neurons continue to maintain & produce circadian rhythm if seperated --Per & Tim proteins increase activity of neurons in the SCN --High Per & Tim=sleepiness --Low Per & Tim=wakefulness |
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4 Stages of Sleep
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Stage 1 (Floating Stage)
-Brief stage before sleep -Brain activity declines --Alpha & Theta Waves Stage 2 (Daydreaming) 1.Theta Waves 2.Sleep Spindles 3.K Complex Stage 3 -Occasional Delta waves -Spindles decrease Stage 4 -Dominated by Delta waves -Synchronized -Typically only in 1st 2 cycles of sleep NON-REM = Stages 2-4 |
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REM Sleep
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-Occurs 80-100min after sleep
-Sleep lightens -Return through stages 3 & 2 to stage 1 -Some Beta Wave Activity -Lasts about 10min Behavioral Characteristics -Muscles relaxed (loss of tone) -Rapid eye movement -Dreams |
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Sleep Waves
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Beta
-Alert & Attentive -High Frequency, Low Amplitude -Desynchronous Alpha -Restful state -Medium Frequency & Amplitude -Becoming synchronous Theta -Rapid, low amplitude |
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Reticular Activating System
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Pontomesencephalon (Pon-Midbrain)-
-Maintains Arousal -Releases acetylcholine and glutamate - maintains arousal -Contribute to cortical arousal -Extend to thalamus, forebrain, basal forebrain -Stimulation results in awakening |
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Raphe Nuclei
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Release serotonin
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Hypothalamus
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-Tract releases histamine
-Tract releases Orexin (Hypocretin)--Stimulates Acetylcholine |
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Basal Forebrain
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-Acetylcholine neurons
-GABA neurons--Sleep requires these neurons |
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Adenosine
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Anti-inflammatory agents
-Inhibits neurons in Basal Forebrain that release Acetylcholine --Decreases arousal -Sleep Debt-Build of Adenosine -Adenosine accumulates when brain is awake & active |
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PGO Waves
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Structures
-(P)Pons-Pons trigger REM onset -(G)Geniculate-Activate lateral Geniculate -(O)Occipital-Activate occipital cortex -Synchronized with eye movements -High amplitude electrical potentials-REM sleep -Waves of brain activity transmitted from: Pons--Geniculate--Occipital Lobe |
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Pons
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-Decrease sensation to sensory stimuli
-Shuts down skeletal muscle activity-Prevent action during REM |
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Nightmare vs. Night Terrors
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Nightmares
-Repeated occurrence of frightening dreams that lead to awakening -Occur mostly during REM Night Terrors (Sleep Terror D/O) -Sudden arousal from sleep & intense fear -Autonomic arousal-Rapid HR & perspiration -Occur mostly during NONREM |
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Narcolepsy
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-Lasts up to 10-20min
Primary Characteristics 1)Irresistible urge to fall asleep that may occur while talking or standing 2)Cataplexy-loss of muscle tone 3)Sleep paralysis or dream-like imagersy (hallucinations) at the beginning or end of episode -30-50% = sleep paralysis -20-40% = dreamlike imagery -Not enough production of orexin |
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Restoration vs. Preservation & Protection Theory
Restoration Theory |
Restoration Theory
-body wears out during the day -sleep puts it back in shape -Evidence: -More strenuous workout = More NREM sleep -NREM deprivation = physical fatigue -REM deprivation = less physical fatigue |
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Preservation & Protection Theory
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Evolutionary perspective
-to preserve energy -Inefficient time to search for food -Provides passive defense |
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Activation-Synthesis Hypothesis
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-Dreams are side effects of mental stimulation for pons
-Synthesis of motor & visual neuron firing with stored memories -Amygdala activation provides emotional context -Frontal cortices deactivated -Allow for illogical dreams |
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Clinico-Anatomical Hypothesis
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-Suggests that dreams are similar to thinking, just under unusual circumstances
-Activity in prefrontal cortex is suppressed -Activity is high in parietal cortex -Patients with damage report problems with binding body sensations with vision and have no dreams |
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Temperature Regulation
-Feedback Circuit |
Negative Feedback – Reduce discrepancies (behavior to relieve disturbance)
Positive Feedback – Stops negative feedback |
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Heat Production vs. Heat Loss
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Heat Production
1)Voluntary: Exercise 2)Involuntary: shivering, metabolism, radiation Heat Loss 1)Radiation –Transfer of heat without contact 2)Conduction –Heat loss due to contact 3)Convection-Heat transferred to air or water 4)Evaporation-Heat via sweat on skin -Temp regulation is an interaction between internal regulation and behavior |
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BioBasis of Temp Regulation
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Hypothalamus-
-Anterior hypothalamus & Preoptic Area -Thermostat of the body |
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Regulation of Thirst
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Regulation occurs by drinking more water than we need & excreting the rest
Biological: -Hypothalamus -Pituitary Gland: -Releases Vasopressin -Acts as anti-diuretic |
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Osmotic Thirst
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Osmometric Thirst
-Increased levels of salt produce drive -Cellular dehydration – Creates osmotic pressure – Cells detect water loss & trigger thirst Receptors -Around 3rd ventricle—Osmoreceptor – Supraoptic Nucleus -OVLT & Subfornical Organ – detect pressure & salt -Receptors in periphery—Stomach |
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Hypovolemic Thirst
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Volumetric Thirst
-Associated with low body fluids (low blood pressure) -Need Water & Salt Detection 1.Baroreceptors on Venus Return 2.Kidney’s: release rennin when low blood volume -Angiotensin: constricts blood vessels, reduces kidney filtration -Subfornical Organ: releases Angiotensin2 into hypothalamus 3.Adrenal Glands – Regulates levels of sodium & potassium – Communicates with sweat & salivary glands |
