Biological Rythms Infradian and Ultradian rhythms Flashcards
What is an infadian rhythm
It is a type of biological rhythms with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder
What is an ultraradian rhythm
It is a type of biological rhythms with a frequency of more than one cake jn 24 hours m, such as the stages of sleep (the sleep cycle)
What is the menstrual cycle
It is an example of an infradian rhythm
It is governed by monthly changes jn hormone levels which regulate ovulation.
The cycle refers to the time between the firstv day of a women’s period to the day before her next period
How long does a typical menstruation cycle take to complete
28 days (although anywhere between 24 and 35 days is normal)
During rhe each cycle, rising levs of the hormone oestrogen cause the ovary to develop an egg and release (ovulation)
After ovulation, the hormone progestogen helps the womb lining to grow thicker, readying the womb for pregnancy.
If the pregnancy foes not occur comes away an leave the body (mentural flow)
What kind of system is the menstrual cycle
It is an endogenous system, however, there is evidence to suggest that it may be influencer by exogenous factors
A study by Kathleen Stern and Mastha McClinton (1998) demonstrate how menstrual cycles may synchronise as a result of the influence of pheromones
What is Stern and McClintok study
Stern and McClintock studied 29 women with history with a history of irregular periods
Samples of pheromones were gathered from nine of the women at different stages of their menstrual cycles via a cotton pad in the armpit
The pads were pads were worn for at least 8 hours to ensure that pheromones were picked up.
The pads were treated with alcohol and frozen, to be rubbed on the upper lip of the other participants
On day one, pads from the start of the menstrual cycle were applied to all 20 women, on day two the were all given a pad from the second day of the cycle and so on
Stern and McClintock found that 68% of women experienced changed to the cycle which brought them closer to the cycle of their “odour donor”
How long does the stages if the sleep stages last
90 minutes
What happens in stage 1 and 2
Stages 1 and 2
This is light sleep where a person may easily be woken. In stages 1, brain waves are high frequency and have a short amplitude.
These are alpha waves
In stage 2, the alpha waves continue but there are occasional random changes in patterns called sleep spindles
What happens in stages 3 and 4
This is known as deep sleep or slow wave sleep.
The brain waves are delta waves with lower frequency and higher amplitude.
It is difficult to wake someone at this point
What happens in the finals stage of sleep (REM sleep)
The body is paralysed yet Brian activity resembles that of the awake brain
During this time, the brain produces that waves and rhe eyes occasionally move around, thus rapid eye movement (REM).
Dreams are mot often experienced during REM sleep, but my also occur in deep sleep
