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Flashcards by molly.rowland1, updated more than 1 year ago
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Created by molly.rowland1
over 9 years ago
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| Question | Answer |
| What are ultradian rhythms? | Biological rhythms that last less than 24 hours. |
| Give a few examples of ultradian rhythms. | Temperature regulation. Hormone secretion. Heart rate. |
| How are ultradian rhythms influenced by endogenous pacemakers and exogenous zeitgebers? | They are largely under endogenous control although there does appear to be some exogenous influence. For example, an ultradian rhythm is body temperature. This is controlled endogenously by our thermoregulatory centre or exogenously by external temperature. |
| What part of sleep is an example of an ultradian rhythm? | The stages of sleep. |
| What are the two main stages of sleep? | REM (rapid eye movement) and NREM (non-rapid eye movement). |
| Describe the stages of sleep within NREM sleep. | Stage one: theta waves appear on the EEG. Myoclonic jerks and the person will still feel like they are awake, this lasts about 10 minutes. Stage two: sleep spindles and K-complexes occur on EEG. Muscles relax and breathing is steady, this also lasts about 10 minutes. Stage 3: delta waves appear on EEG, once it is predominantly delta waves this signifies stage 4. Stage 3 and 4 are known collectively as slow wave sleep, there may be occasional twitches of the hands and feet but the person is in a very deep sleep. Stages 4 last about 30 minutes before recurring back to stages 3 and 2 rapidly. |
| Describe REM sleep. | Eyeballs move under eyelids, breathing is rapid and heart rate increases. The rest of the body is paralysed and if woken in this stage they are likely to report that they have been dreaming. |
| What happens after the first complete cycle of NREM and REM sleep? | Sleep alternates between stages of slow wave sleep and REM. The periods of REM become longer as the night progresses and the expense of time in SWS. |
| How long in total is each cycle of sleep? | 90 minutes. |
| What evidence is there for a brain mechanism controlling the alternation of REM and NREM sleep? | The regularity of the 90-minute cycle. |
| What structure in the brain do researchers think is responsible for the endogenous control of sleep? | The locus coeruleus in the brainstem. |
| What evidence is there that the locus coeruleus is responsible for the endogenous control of sleep? | Jouvet,1972: Destroyed the locus coeruleus in cats which permanently destroyed their ability to enter REM sleep. |
| What issues are there with Jouvet's research? | REM sleep is critical for survival, so by preventing the cats entering REM sleep caused their deaths. This is extremely unethical allowing cats to be put through the torture of dying from lack of REM sleep. |
| What methodological issues are there with Jouvet's study? | As it is performed on cats it can't necessarily be generalised to humans as we are completely different species. However, this wouldn't matter according to the biological approach as it would claim that we have a locus coeruleus, therefore, it must have the same underlying biology and can, therefore, be applied to humans. |
| What specific cells in the locus coeruleus are responsible for the endogenous control of sleep? | Cholinergic cells. |
| What is meant by the term 'cholinergic cells'? | They are cells that use the neurotransmitter acetylcholine. |
| What research supports the role of cholinergic cells? | Webster and Jones - the loss of REM sleep is proportionate to the number of cholinergic cells destroyed. |
| Why would the idea of brain mechanisms controlling our sleep be considered deterministic and also argue in favour of the nature side of the nature vs nurture debate? | It is deterministic because it is suggesting we have no free will over our sleep. It is in favour of the nature side because it is an internal mechanism controlling our behaviour. |
| What other example of ultradian rhythms can be discussed on the exam? | Neurochemical activity. |
| What did the study by Kennedy et al show about the ultradian rhythm of neurochemical activity? | Kennedy measured the levels of tryptophan and 5-hydroxy indoleacetic acid (5-HIAA) in the cerebrospinal fluid of 12 healthy volunteers, they collected the CSF by lumbar puncture. They removed 1ml of fluid every 10 minutes, they found evidence of ultradian rhythms in the concentrations of both these chemicals. |
| How can the findings of Kennedy et al be applied to real life? | It may have a significance for the understanding of mental problems for which these chemicals are implicated. 5-HIAA and TRP are both essential in the production of the neurotransmitter serotonin which is understood to play a role in a range of problems including anorexia, bulimia, OCD, and depression. |
| What issue is there with the methodology of this study? | Although the study was carried out on healthy volunteers, the lumbar punctures are painful and invasive and therefore place stress on the body. The body can react to stress in numerous ways so it is possible that the changes in concentrations of these chemicals could be the body's response to the stress it is being put under. |
| What further research supports Kennedy? | Salomon et al - Took CSF samples from 15 depressed patients at 10-minute intervals for 24 hours before and after antidepressant treatment. A change in ultradian cycle length of 5-HIAA was observed following the treatment, this suggests that abnormal ultradian rhythms are part of the general pathophysiology of depression. |
| What issues were there with the Solomon study? | Again lumbar punctures are painful so it seems unethical to put healthy people through that however the pain may even make the participants depression even worse. |
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