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26 Cards in this Set

  • Front
  • Back
Circadian Rhythm
-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
Circadian Rhythm
2 Findings
1) Need external Cues-keep us on track

2) Rhythms are adjustable-1wk to shift circadian rhythm
Locus of Clock
Suprachiasmatic Nucleus (SCN)
-hypothalamus above optic nerves
-Receives light levels--Retino-hypothalamic pathway
-Removal abolishes rhythm of sleep and waking
How The SCN Keeps Time
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
4 Stages of Sleep
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
-Typically only in 1st 2 cycles of sleep

NON-REM = Stages 2-4
REM Sleep
-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
Sleep Waves
-Alert & Attentive
-High Frequency, Low Amplitude

-Restful state
-Medium Frequency & Amplitude
-Becoming synchronous

-Rapid, low amplitude
Reticular Activating System
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
Raphe Nuclei
Release serotonin
-Tract releases histamine
-Tract releases Orexin (Hypocretin)--Stimulates Acetylcholine
Basal Forebrain
-Acetylcholine neurons
-GABA neurons--Sleep requires these neurons
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
PGO Waves
-(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
-Decrease sensation to sensory stimuli
-Shuts down skeletal muscle activity-Prevent action during REM
Nightmare vs. Night Terrors
-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
-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
Restoration vs. Preservation & Protection Theory

Restoration Theory
Restoration Theory
-body wears out during the day
-sleep puts it back in shape
-More strenuous workout = More NREM sleep
-NREM deprivation = physical fatigue
-REM deprivation = less physical fatigue
Preservation & Protection Theory
Evolutionary perspective
-to preserve energy
-Inefficient time to search for food
-Provides passive defense
Activation-Synthesis Hypothesis
-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
Clinico-Anatomical Hypothesis
-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
Temperature Regulation
-Feedback Circuit
Negative Feedback – Reduce discrepancies (behavior to relieve disturbance)

Positive Feedback – Stops negative feedback
Heat Production vs. Heat Loss
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
BioBasis of Temp Regulation
-Anterior hypothalamus & Preoptic Area
-Thermostat of the body
Regulation of Thirst
Regulation occurs by drinking more water than we need & excreting the rest
-Pituitary Gland:
-Releases Vasopressin
-Acts as anti-diuretic
Osmotic Thirst
Osmometric Thirst
-Increased levels of salt produce drive
-Cellular dehydration – Creates osmotic pressure – Cells detect water loss & trigger thirst

-Around 3rd ventricle—Osmoreceptor – Supraoptic Nucleus
-OVLT & Subfornical Organ – detect pressure & salt
-Receptors in periphery—Stomach
Hypovolemic Thirst
Volumetric Thirst
-Associated with low body fluids (low blood pressure)
-Need Water & Salt

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