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40 Cards in this Set

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What are the body's two nromal endogenous cycles?
1. Circadian rhythm

2. Circannual rhythm
What is an endogenous circandian rhythm?
Internal rhythms that last a day. In humans, the uninterrupted cycle lasts 24.2 hours. Deals mainly with sleeping and waking.
What is an endogenous circannual rhythm?
An internal calendar of the seasons. This is mainly for hibernating animals and for winter and summer coats.
What are the three mechanisms of the biological clock?
1. Suprachiasmatic nucleus

2. Melatonin

3. Biochemistry
What is the function of the suprachiasmatic nucleus?
Sleep and temperature control in the hypothalamus, with impulse patterns that follow circadian rhythms.
What is the function of melatonin?
It is a hormone of the pineal gland that is released 2-3 hours before bedtime increases feelings of sleepiness, and also stimulates the SCN to reset the clock.
What is the function of per and tim in fruit flies?
Production of these two genes/hormones increases during daylight hours, the two interact with another protein to induce sleepiness. Production stops during dark hours.
What is a zeitgeber?
A stimulus that resets a cycle.
What are free-running biological cycles?
They reset without the need for a stimulus. Humans don't have these.
What happens to hamsters if they live in a full-light enbironment?
It causes the SCN's in the left and right hemisphere to get out of whack, this produces two periods of wakefulness followed by two of sleep.
How does light reset the SCN?
The retinohypothalmic path. A direct connection between the retina and the SCN that signals stimulation. Axon innervated ganglia let hypothalamus know light is hitting the eye.
What are the two forms of jet lag?
1. Phase-delay

2. Phase-advance
What is phase-delay jet lag?
When traveling west, we get more sun and stay awake longer (and sleep later). Delayign the phase from starting over.
What is phase-advance jet lag?
Traveling east normally leads to earlier sleep and wakefulness. Trying to start phase over early.
What does working the night shift do?
Working under daylight-intensive lights can alter the normal circadian rhythm. Repeated adjustments of the circadian rhythm can cause damage to the hippocampus.
How can the stages of sleep be measured?
EEG and breathing and heart rate.
What does an EEG measure?
Gross brain waves. Different types signal different stages.
What are alpha waves and what do they signal?
8-12 cycles per second. Signal a relaxed state of consciousness.
What is stage 1 sleep and what occurs here?
The wave patterns are irregular, jagged, low-voltage bursts. this one occurs only once during hte night, just as you're falling asleep.
What is stage 2 sleep and what occurs here?
Sleep spindles and K-complexes.
What occurs during sleep stages 3&4?
Slow-wave sleep, large-amplitude waves. Very difficult to wake someone, they will be very groggy and fall back asleep easily. Night terrors and "jolts" happen here.
What is REM sleep and what happens here?
Rapid eye movements, near-conscious breathing and heart rates. Fast low-voltage brain waves (saw-tooth). Very closely resemble conscious person working on a problem.
What is paradoxical sleep?
Very active brain, but every msucle in the body relaxed. Complete inability to generate a contraction. Common in animals, b/c animals don't have REM.
What is non-REM sleep/
All the other stages. You can dream in any of the stages, but the dreams are usually shorter and less explicity.
What is the first cycle of sleep?
1-2-3-4, approximately 90 minutes.
What causes you to go through the first stage quicker?
The more tired you are.
What is the second sleep cycle?
3-2-REM. 30-90 minutes.
What is the general cycle of sleep?
2-3-4-3-2-R. 90 minute cycles.
As the night progresses, how do the times in stages 3,4, and REM change?
3&4 shorten, REM lengthens. The longer you sleep, the more dreaming you do.
Why don't you remember dreams from REM sleep?
The hippocampus doesn't turn on.
What are the 4 brain structures of arousal?
1. Reticular formation

2. Locus coerulus

3. Basal forebrain

4. Hypothalamus
What is the function of the reticular formation in arousal?
The pontomesencephalon is here. Stimulation will wake a sleeper or further arouse someone awake instantly.
What is the function of the locus coerulus in arousal?
Structure in the pons that releases norepinephrine in response to "meaningful events"
What is the function of the basal forebrain in arousal?
This is the part of the hypothalamus that releases ACh.
What is the function of the hypothalamus in arousal?
Histamines are released which cause arousal in the brain.
What happens to body temperature as you fall asleep?
It reduces about 1.5 degrees.
What is the function of adenosine in getting to sleep?
It inhibits the basal forebrain (inhibits the inhibitory).
How does caffeine work?
It inhibits the adenosine. It inhibits the inhibitor that inhibits the inhibitor.
What is the function of prostaglandins in getting to sleep?
They are produts of the immune system that suppress the parts of the hypothalamus related to arousal.
What is the function of GABA in getting to sleep?
It is the most common inhibitory substance found specifically in the basal forebrain.