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36 Cards in this Set
- Front
- Back
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Which rhythm repeat time is longer than a day?
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Infradian
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Which rhythm repeat time is shorter than a day?
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Ultradian
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Which rhythm repeat time is about a day?
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Circadian
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What causes a circadian rhythm to be 24 hours?
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External cues such as sunlight
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How long is our circadian rhythm without external cues?
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About 26 hours
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What stucture acts as our internal clock?
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Suprachiasmatic nucleus
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How many nuclei are in the SCN?
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10,000
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What happened in experiments where rats were kept in the dark all the time?
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They still exhibited regular sleep/wake cycles
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What happened when the rat's SCN was obliterated?
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The rat lost all semblence of a sleep/wake schedule.
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When the mutated Tau was transplanted into a wild-type rat, what was the result?
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Loss of circadian rhythm
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What exactly about the SCN actually causes the circadian rhythm?
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Fluctuations in the firing rate of the neurons in the SCN.
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What helps synchronize the neurons of the SCN?
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Gap junctions
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What NT helps synchronize the SCN?
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GABA
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How many "clock" genes are there and what are their purposes?
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1. 4
2. Per & Cry are proteins 3. Clock and BMAL are transcriptional regulators of Per and Cry |
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What process is very important in the regulation of Per and Cry?
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Negative feedback (there is also a positive feedback)
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Explain how negative feedback works.
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1. As Per and Cry are transcribed in excess they form dimers
2. The dimers then go back and interact with Clock and BMAL. Once a significant amount of Per and Cry dimers have been degraded, Clock and BMAL can cause the transcription of Per and Cry |
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What happens if you knock-out any of the genes for the internal "clock"?
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You no longer have a circadian rhythm.
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What substance proves that the clock drives the firing of the neuron and not the other way around.
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Tetrodotoxin - blocks the action potentials but when administration ends the clock fires back up
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What is the direct pathway from the retina to the SCN?
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Retino-hypothalamic tract
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What NT released in from the SCN helps in entraining?
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Glutamate (along with GABA for rhythm)
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If intracellular concentrations of this element are increased, entraining occurs.
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Calcium
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Is the output of the SCN diffuse of not?
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Very diffuse throughout the cortex
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Sleep is a(n) (active/passive) process
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Active
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What are the two sleep states?
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1. NREM
2. REM |
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What is the best way to look at brain activity during sleep?
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EEG
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What does the EEG look like while we are awake?
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High frequency, desynchronized, low voltage
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What does the EEG look like while we are in NREM?
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Low frequency, high voltage synchronized firing
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What does the EEG look like while we are in REM?
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Is like the awake pattern but muscles are paralyzed and eyes are moving a lot.
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As we age (3)...
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1. Sleep less
2. REM stays the same 3. NREM decreases |
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What maintains wakefulness? What happens with a tumor here?
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1. Reticular activating system
2. Coma |
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What neurons produce NREM sleep?
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Thalamocortical neurons
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What happens to cause NREM sleep?
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1. P-type Ca channels are open allowing bursting to occur
2. Burtsing causes slow wave cortical formations seen as NREM sleep |
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REM-ON centers release what NT?
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Ach
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REM-OFF centers release what NT?
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Nor-epinephrine and Seratonin
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What is described as the difference between our need for sleep and the timing mechanism for sleep?
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Sleep pressure
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Does circadian rhythm really ever change?
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Not really
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