biological rhythms

Question 1

a biological rhythm

Answer 1

a biological rhythm is a cyclical variation over some period of time in physiological and psychological processes

Question 2

circadian rhythms

Answer 2

take just 24 hours

Question 3

examples of circadian rhythms

Answer 3

• sleep/wake cycle: awake during day, asleep during night
• hormone concentrations: vary during the body over the course of a day. the production of melatonin from the pineal gland, peak levels occur during hours of darkness
• core body temperature: at its lowest (36) at 4:30am and its highest (38) about 6pm

Question 4

siffre

Answer 4

In 1975 Siffre spent six months underground in an environment completely cut off from all EZs. Although he organized his time in regular patterns of sleeping and waking, his body seemed to have a preference for a 25-hour rather than a 24-hour cycle. This implies that circadian rhythms are mainly controlled by EP’s rather than EZ’s

Question 5

endogenous pacemakers

Answer 5

internal biological structures control and regulate the rhythm

Question 6

exogenous zeitgebers

Answer 6

(time givers) external environmental factors influence the rhythm

Question 7

endogenous pacemaker

Answer 7

internal biological structures control and regulate the rhythm

Question 8

ultradian rhythms

Answer 8

a biological rhythm occurring more than once within a day. it has a frequency of more than one cycle in 24 hours such as the 5 stages of sleep that occur during the night in humans

Question 9

infradian rhythm

Answer 9

a biological rhythm taking place over a period of over 24 hours. they may be cycles lasting days, weeks, months or annually

Question 10

examples of infradian rhythms

Answer 10

• menstrual cycle
  —- stern and mcclintock (1998): demonstrated that exogenous as well as endogenous factors can affect the menstrual cycle. women with irregular periods were exposed to pheromones of other women at different stages of their cycle. after several days, the pp’s period began to align with their ‘odour donor’
• seasonal depression

Question 11

suprachiasmatic nucleus

Answer 11

circadian rhythms are driven by our body clocks, found in all the cells of the body and synchronised by the master cirrcadian pacemaker called the suprachiasmatic nucleus (SCN) found in the hypothalamus