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Where is circadian rythym controlled in the brain
Suprachiasmatic nucleus (SCN), located just above the optic chiasm in the hypothalamus
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How, and when is the Suprachiasmatic nucleus (SCN) reset
It is reset by retinal reception of light (blue light photo receptors) and it is reset everyday
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Light stimulates what cells to provide additional photic input to the Circadian rhythm
Photoreceptors like Rods and cones, as well as ganglion cells
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The Suprachiasmatic nucleus (SCN) receives what type of physiological inputs to set its rhythm
Serotoninergic inputs from the Raphe nucleus
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Where does the Suprachiasmatic Nucleus (SCN) project messages
Indirectly to the Pineal gland via the spinal cord
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What is the role of the pineal gland in Circadian Rhythm
- Synthesis melatonin which is stopped by the presence of light
- This has a direct effect on the sleep/wake cycle
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What happens to core temperature, during sleep
It drops a 1˚C quickly then returns after waking
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What happens to the amount of growth hormone when one is sleeping
It increases many fold in comparison to being awake
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What are some of the internal conditions that the circadian rhythm helps keep in a constant range
- BP
- Temp
- Acidity
- Metabolism
- Sexual behavior
- Cognition
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Sleep is mediated by what structure in the brain
Reticular formation
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What are the methods for defining the stage of sleep a patient is in
- Rapid Eye movement
- Brain Waves (EEG)
- Physiological markers
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What happens in Non REM (NREM)
- Decrease in muscle tone as stages progress
- Stages; 1 drowsy, 2 light sleep, 3 deep sleep
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What happens in REM distinguishing it from NREM
- Rapid eye movement
- Intense Cerebral activity
- Paralysis of muscles
- Obscure Dreaming
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The reticular formation includes what other areas of the brain to initiate sleep
- Locus coeruleus
- Raphe
- Tegmentum
- Reticular Nuclei of Thalamus
- Nucleus Solitarius
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What is the role of Adenosine in sleep
It is an inhibitory transmitter that promotes sleep, it gradually increases while awake and decreases during sleep
Caffeine blocks adenosine receptors therefore inhibiting it from triggering the urge to sleep
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REM is turned on and off in a normal sleep cycle, what triggers this
- Cholinergic and GABAnergic neurons turn it on
- Noradrenergic and Serotoninergic neurons turn it off
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Where do the neurons come from that regulate the REM cycle
- Cholinergic - Pontine Reticular formation
- GABAergic - Reticular formation
- Noradrenergic - Locus Coeruleus
- Serotoninergic - Raphe
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What neurotransmitter is not very active in the day but very active during sleep
GABA
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How does the amount of ACh compare during REM and NREM
It is very high during REM and very low during NREM
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How does the amount of GABA compare in REM and NREM
It is very high during REM and moderately high in NREM
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How do the levels of NE compare in REM and NREM
They are very low in REM and moderately low in NREM
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How do the levels of 5-HT compare in REM and NREM
Very low in REM, moderately low in NREM
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What are the EEG rhythms during awake/sleep
- Awake - beta
- Stage 1 (drowsy) - theta
- Stage 2 (light sleep)- K-complex
- Stage 3 (deep sleep)- Delta
- REM - beta
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How do sleep patterns change with age
- Newborns have sleep spread through the whole day
- 1 year olds have an average of two naps in the day
- 4 year olds have one nap on the day
- 10 year olds sleep longer, adults shorter
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When is someone most likely to remember their dreams
When they wake in the middle of REM
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During sleep, what sections of the brain are less active
- Frontal cortex
- Primary visual cortex
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During sleep, what sections of the brain have increased activity
- Extrastriate visual areas
- Anterior Cingulate Gyrus
- Pontine Brainstem
- Hippocampus
- Thalmus
- Amygdala
- Pons
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What specific deficits in memory are found from sleep deprivation
- Procedural memory
- Episodic memory
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Sleep deprivation increases a subjects belief that
- They are right, especially when they are wrong
- This is often causes accidents
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What hormones are dependent on sleep and in even an hour of sleep missed per night for several night can effect
- Cortisol
- Growth Hormone
- Follicle stimulating (FSH)
- Luteinizing Hormone (LH)
- Leptin
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What are the two primary underlying reasons for sleep apnea
- Obstructive air flow
- Problems in the brainstem for controlling respiration during sleep
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What is happening in the body of a patient with restless leg syndrome
They have a decreased dopamine activity, can be treated with L-Dopa
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When do Parasomnias (sleep talking, walking, terrors) occur
During NREM deep sleep (stage 3)
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REM behavior disorder
- Loss of REM muscle atonia while dreaming during REM sleep stages, therefore they act out their dreams
- Primarily associated with Parkinsons disease
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What can be a purpose of measuring the speed a patient entering REM
It can help determine if there is sleep deprevation
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What common illnesses can sleep deprevation contribute to
- Obesity
- Diabetes
- Hypertension
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