biological rhythms: infradian + ultradian rhytms

Question 1

infradian rhytm

Answer 1

-type of biological rhythm w duration of over 24 hrs
-eg menstrual cycle, seasonal affective disorder

Question 2

menstrual cycle

Answer 2

-governed by monthly hormone level cycles which regualte ovualtion
-28 days
-rising levels of oestrogen cause ovary to develop+ release an egg
-after ovulation, progestrone helps womb thicken to ready for pregnancy

Question 3

synchronised menstrual cycle

Answer 3

-endegenous system as its inside body
-but evidence to suggest an influence from exogenous factors such as cycles from othern women

Question 4

synchronised menstrual cycle

stern + mc Clintock (1998)

Answer 4

-studied 29 women w irregular periods
-the pheromones of 9 of these women were placed on upper lip of remaining 20 ppts
-found 68% of women experinced chnage in cycle closer to ‘odor donor’
phermone= chemical that an animal produces which changes behvaiour of another animal of some species

Question 5

seasonal affective disorder

Answer 5

-main symptons: low mood, general lack of activity + interest in life
-triggered by shortened day light hours as more melatonin then produced (tired)
-circuannual rhytm
-info about light from eyes + optic nerves goes scn, then communicates this info to pineal gland
-the pg secrets melatonin when dark out + inhibits production when its light

Question 6

aschoff + weaver (1976)

Answer 6

-ppts spent 4 weeks in ww2 bunker deprived of natural light
-ppts adjusted to a cr between 24+25 hrs (1 ppt had one of 29hrs)
-these show the natural s/w cycle may be slightly longer than 24hrs buts entrained by exogenous zietgebers associated without 24hr day eg meal times+light

Question 7

ultradian rhytm

Answer 7

-w a frequency less than 24 hrs such as 5 stages of sleep, blinking + heart rate

Question 8

ultradian rhytm

stages of sleep

Answer 8

-sleep about 8hrs a day
-what we know about this comes from sleep studies + eegs
-sleepcycle consists of 5 stages w diff brain waves
-cycle repeats every 90 minutes

Question 9

stage 1

Answer 9

-4-5% of time
-lightr sleep
-muscle activity slows down, occasional muscle twitch
-theta wave length

Question 10

stage 2

Answer 10

-45-55% of time
-breathing pattern + heart rate slows
-decrease in body temp
-lighht sleep
-theta waves

Question 11

stage 3

Answer 11

-4-6%
-brain begins to generate
-deep sleep
-delta waves

Question 12

stage 4

Answer 12

-12-55%
-VERY DEEP
-rhythmic breathing
-limited muscle activity
-delta waves

Question 13

stage 5
REM

Answer 13

-20-25%
-rem waves similar to beta
-waves speed up
-dream occurs
-muscles relax+ heart rate rise
-breathing is rapid + shallow

Question 14

evaluation

Answer 14

-lab studies: controlled limits extraneous factors = high internal validity
-high element of control- independent variable is directly impacting dependent variable
-BUT, artifical- not realistic, low ecological validity, confounding variable
-eegs- low spatial resolution, uncomfortable