Biological Rhythms: Infradian Rhythms Flashcards
what are infradian rhythms?
- a cycle that takes longer than 24 hours to complete
- can be a month or year or seasonal
what is an example of a infradian rhythm?
menstrual cycle
what is the menstrual cycle?
it is governed by monthly changes in the hormone levels which regulate ovulation
what type of system is the menstrual cycle?
endogenous system but can be affected by exogenous factors
how long does the menstrual cycle last?
- first day of a women’s period to the day before her next period
- approximately 28 days (24-35 days)
what happens during each cycle?
- rising levels of the hormones oestrogen causes the ovary to develop an egg and release it (ovulation)
what happens after ovulation?
- hormone progesterone helps the womb lining to grow thicker, readying the womb for pregnancy
- if pregnancy does not occur, the egg is absorbed into the body, the womb lining comes away and leaves the body (menstrual flow)
what can the menstrual cycle be influenced by even though it is an endogenous system?
exogenous factors, such as cycles other women
who are the researchers involved with demonstrating synchronisation of menstrual cycles?
Stern and McClintock
what are pheromones?
chemical signals that organisms release to communicate with other members of their species
how are pheromones often released and detected?
- sweat
- urine
- faeces
and are detected through smell
what was the aim of Stern and McClintock?
- see if the menstrual cycle can be synchronised by the influence of female pheromones
what was the procedure of Stern and McClintock?
- 29 women with a history of irregular periods
- pheromone samples were gathered from 9 of these women at different stage of the menstrual cycle via a cotton pad place in their armpit, this was worn for 8 hours to pick up the pheromones
- the pads were frozen and treated with alcohol to be rubbed on the upper lip of the other ppts
what were the results of Stern and McClintock?
- on day one, pads from the start of the menstrual cycle were given to each women and on day 2 pads from the second day of the cycle and so on
- 68% of women experienced changes to their cycle which brought them closer to the cycle of the odour donor
what is SAD?
- seasonal affective disorder
- depressive disorder which has a seasonal pattern of onset, described and diagnosed as a mental disorder in the DSM-5