Physio Psych Chapter 9
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- What are the body's two nromal endogenous cycles?
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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?
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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?
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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?
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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.