Biopsychology Flashcards
What is a circadian rhythm?
A type of biological rhythm that is subject to a 24 hour cycle.
What are some examples of circadian rhythms?
Sleep-wake cycle - we feel drowsy at night and awake at day (due to Exogenous zeitgebers our biological clock- endogenous pacemakers)
Body temperature - we are 38° in the evening and 36° in the early morning
Key studies into circadian rhythms
- siffre’s cave study in which he lived in a number of caves deprived of natural light for 2 months and 6 months and found that his free running biological rhythm settled down to 24-25 hours
- aschoff and wever who had participants spend weeks in a ww2 bunker and all their biological rhythms settled down to 24-25 hours
- folkard who had participants living in a cave gradually sped up the clock so 24 hours past in 22. No on managed to adjust to the new rhythm
Evaluation of circadian rhythms
+ practical application in to shift work e.g this research helps us understand adverse consequences of shift work during circadian troughs (6am) more accidents/ poor health
+ practical application into drug treatments e.g circadian rhythms have revealed peak times in the day where drugs are most effective
- research into sleep-wake cycles have small sample sizes
- poor control in studies as participants had access to lamps
What is an infradian rhythm?
A biological rhythm with a frequency of less than one cycle in 24 hours
What are some examples of infradian rhythms?
Female menstrual cycle - governed by monthly changes in hormone levels, usually takes 28 days to complete
Seasonal affective disorder - mental disorder characterized by symptoms of depression in the winter months due to long nights, short days and therefore lots of melatonin being produced
Key studies into infradian rhymths
McClintock demonstrated how mensural cycles may synchronize as a result of pheromones. He got 29 women with irregular periods and rubbed samples of pheromones from diner women on their upper lip. 68% of women synchronized closer to their oder doner
Evaluation of infradian rhythms
+ mcClintocks study may support evolutionary idea that it was advantageous for females to menstruate and fall pregnant at the same time so that newborns could be cared for collectively
+ animal studies show the role of pheromones on cycles. Sea urchins release pheromones into the water which signals for other urchins to eject their sex cells simultaneously
- methodological issues, many things may affect a mensural cycle e.g stress, exercise, diet (confounding variables) also study relies on self reports
What is the endocrine system?
A major system that instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs in the body
What are the main glands associated with the endocrine system?
Pituitary (master gland), hypothalamus, thyroid, adrenals, pancreas, ovaries, testies
How do the endocrine system and ANS work together?
During a stressful event the hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system. Next the stress hormone is released from the adrenal medula into the bloodstream.
- Adrenalin causes blood pressure and heart rate to increase which are both required during fight or flight
Following this the parasympathetic nervous system takes affect and returns the body to its usual resting state
What is an ultradian rhythm
A biological rhythm that occurs more than once in 24 hours.
- stages of sleep
What are the 5 stages of sleep
Stages 1 and 2
Light sleep with alpha and theta waves
Stages 3 and 4
Deep sleep with delta waves
Stage 5
Rem sleep, body is paralyzed but brain activity increases
