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18 Cards in this Set
- Front
- Back
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What is an "endogenous circannual rhythm?"
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Endogenous Circannual Rhythm: An internal calendar which prepares a species for annual seasonal changes.
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What is an "endogenous circadian rhythm?"
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Endogenous Circadian Rhythm: Internal rhythms which last about a day (e.g. wakefulness and sleepiness).
- - - In humans, the circadian rhythm has a self-generated duration of about 24.2 hours. |
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What are the mechanisms of circadian rhythms?
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Mechanisms of Circadian Rhythms:
- The Suprachiasmatic Nucleus (SCN) - Genes that produce certain proteins - Melatonin levels |
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What is the "suprachiasmatic nucleus?"
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Suprachiasmatic Nucleus (SCN): Nucleus located above the optic shiasm in the hypothalamus. The SCN controls the rhythms for sleep and temperature. The neurons of the SCN generate impulses that folow a circadian rhythm.
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What is a "free-running rhythm?"
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Free-running Rhythm: A rhythm that occurs when no stimuli reset or alter it (e.g. wrist-watch analogy).
- - - In a study using hamsters housed under constant light, the SCN in the right hemisphere got out of phase with the SCN in the left hemisphere - causing two periods of wakefulness and two periods of sleep. |
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What is a "zeitgeber?"
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Zeitgeber: Stimulus that is necessary for resetting the circadian rhythm (e.g. light).
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What is "jet-lag?"
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Jet-Lag: A disruption of our biological rhythms due to crossing time zones.
- Phase-Delay: what happens to our circadian rhythms when we travel west, as we stay awake late and awaken the next day already partly adjusted to the new schedule. - Phase-Advance: What happens to our circadian rhythms when we travel east - as we tend to sleep and awaken earlier than usual. - - - - Recent studies have indicated that repeated adjustments of the circadian rhythm can damage the hippocampus and cause memory loss. |
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What is "adenosine?"
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Adenosine: An important inhibitor of the basal forebrain arousal system.
- Caffeine increases arousal by inhibiting adenosine. |
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What is "orexin?"
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Orexin: A peptide neurotransmitter released in a pathway from the lateral nucleus of the hypothalamus high responsible for the ability to stay awake.
- - - Stimulates acetylcholine-releasing cells in the forebrain and brain stem to increase wakefulness and arousal. |
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How is the "basal forebrain" involved in arousal and drowsiness?
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Basal Forebrain: An area just anterior and dorsal to the hypothalamus whose axons release "acetylcholine" and "GABA".
- Damage to the basl forebrain leads to decreased arousal, impaired learning and attention, and more time spent in non-REM sleep. |
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How is the "hypothalamus" involved in arousal and drowsiness?
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Certain areas of the hypothalamus stimulate arousal by releasing "histamine" and "orexin" or "hypocretin".
- - Antihistamine drugs produce drowsiness if they cross the blood-brain barrier. Orexin stimulates acetylcholine-releasing cells in the basal forebrain and brain stem. |
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What are some characteristics of REM sleep?
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Characteristics of REM sleep:
1. - The pons triggers the onset of REM sleep. 2. - Pons-geniculate-occipital (PGO) waves: a distinctive pattern of high amplitude electrical potentials associated with REM sleep. 3. - The pons also relays messages to inhibit motor neurons in the spinal cord during REM sleep. 4. - REM sleep depends on both serotonin and acetylcholine activity for its onset and continuation. |
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What is "ionsomnia" caused by?
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Causes of Insomnia:
- Caused by a number of factors including noise, stress, pain medication. - Can also be the result of disorders such as epilepsy, Parkinson's disease. depression, anxiety, or other psychiatric conditions. - Dependence on sleeping pills and shigts in the circadian rhythms can also result in insomnia. - Biological rhythm abnormalities (e.g. tryng to sleep while body temperature rises). |
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What are the three categories of insomnia?
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The Three Categories of Insomnia:
1. - Onset insomnia: Trouble falling asleep. 2. - Maintenance insomnia: Waking up frequently during the night after falling asleep. 3. - Termination insomnia: Waking up too early and can not go back to sleep. |
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What is "sleep apnea?"
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Sleep Apnea: Inability to breath during sleep for a prolonged period of time. Obesity is a common cause of this disorder, particularly in men. It is a possicle cause of sudden infact death syndrome.
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What are some of the functions of sleep?
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Functions of Sleep:
1. - Energy conservation 2. - Restoration of the brain and body. 3. - Memory consolidation. |
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What are some of the functions of REM sleep?
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Functions of REM Sleep:
1. - Species with the greatest total amount of sleep have the highest percentage of REM sleep. 2. - REM sleep deprivation leads to increased attempts at REM sleep. 3. - REM sleep has been implicated in memory storage and as a way of getting oxygen to the corneas. 4. - During REM: The brain may discard useless connections. Learned motor skills may be consolidated. |
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What are some biological perspectives on dreaming?
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Biological Perspectives on Dreaming:
1. - Ativation-Synthesis Hypothesis: During sleep, many brain regions become arctivated, so the brain creaste a story to make snse of all this activity. Random nerve cell firings + cortical interpretation of random firings. 2. - Clinico-Anatomical Hypothesis: Eother internal or external stimulation activates parts of the perietal, occipital, and temporal cortex. No visual information overrides the stimulation and no criticism of the prefrontal cortex censors it, so it develops into hallucinatory perceptions. |
