Biological Rhythms Flashcards
(17 cards)
What is a biological rhythm?
A biological rhythm is a change in body processes/behaviour in response to cyclical changes inside and outside the body.
What are the types of biological rhythms?
There are three types of biological rhythms: Circadian, Ultradian, and Infradian rhythms.
What is an ultradian rhythm?
Ultradian rhythms last less than 24 hours, meaning there is more than one cycle in a 24-hour period.
Example: Sleep stages, which cycle from light sleep to deep sleep to REM sleep, each lasting 90-100 minutes.
What is a strength of research into ultradian rhythms?
✅ Supporting evidence
EEG research has identified brain activity during sleep stages, providing strong evidence for the cyclical nature of sleep stages (ultradian rhythm). This adds credibility to the theory.
What is another strength of research into ultradian rhythms?
✅ Reliability
The use of controlled laboratory conditions and brain scanning techniques (e.g., EEG) in studies on ultradian rhythms makes the research reliable. Findings can be replicated to check consistency, adding credibility.
What is a final strength of research into ultradian rhythms?
✅ Validity
EEG recordings provide high temporal resolution, meaning brain activity is accurately measured. This ensures the research has validity when studying sleep stages as an ultradian rhythm.
What is an infradian rhythm?
Infradian rhythms last longer than 24 hours, meaning there is less than one cycle in a 24-hour period.
Example: Menstrual cycle, which lasts 28 days on average and is regulated by endogenous pacemakers and exogenous zeitgebers.
What is a strength of research into infradian rhythms?
✅ Supporting evidence
Studies have shown that pheromones can synchronize menstrual cycles, supporting the idea that exogenous zeitgebers regulate infradian rhythms.
What is another strength of research into infradian rhythms?
✅ Further supporting evidence
A study found that when a woman spent months in a cave, her menstrual cycle shortened from 28 days to 25 days, showing how light (an exogenous zeitgeber) affects infradian rhythms.
What is a limitation of research into infradian rhythms?
❌ Methodological flaws
Factors such as stress, diet, and exercise can affect menstrual cycles. Small sample sizes used in research make findings hard to generalise, raising concerns about the credibility of conclusions.
What is a circadian rhythm?
Circadian rhythms last 24 hours, meaning there is one cycle in a 24-hour period.
Example: Sleep/wake cycle, regulated by endogenous pacemakers and exogenous zeitgebers like light.
What are endogenous pacemakers and exogenous zeitgebers?
Endogenous pacemakers: Internal body clocks (e.g., SCN and pineal gland) regulate biological rhythms.
Exogenous zeitgebers: External factors like light that help synchronise biological rhythms with the environment.
Outline the role of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle.
Endogenous pacemakers:
Internal body clocks that help regulate biological rhythms like the sleep/wake cycle.
Example: The SCN and pineal gland.
Exogenous zeitgebers:
External factors that synchronise biological rhythms with the outside world.
Example: Light influences melatonin secretion from the pineal gland.
What is a strength of the role of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle?
✅ Supporting evidence
Research on genetically mutated hamsters showed that the SCN (an endogenous pacemaker) governs circadian rhythms, reinforcing the idea that the SCN plays a crucial role in regulating the sleep/wake cycle.
What is another strength of the role of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle?
✅ Supporting evidence from blind people
Blind individuals who have some light perception maintain normal circadian rhythms, while those with no light perception show abnormal circadian rhythms. This supports the role of light (exogenous zeitgebers) in regulating sleep/wake cycles.
What is a limitation of the role of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle?
❌ Overstated role of exogenous zeitgebers
Individuals in Arctic regions with prolonged exposure to light maintain normal sleep patterns, suggesting that exogenous zeitgebers like light may have little effect in certain cases. This raises concerns about the credibility of the theory.
What is a final strength of the role of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle?
✅ Practical applications
Research on jet lag has led to better understanding of how circadian rhythms are affected by changes in light exposure, helping to reduce jet lag symptoms. This demonstrates real-world benefits of understanding the interaction between endogenous pacemakers and exogenous zeitgebers.
