Biological Rhythms

Question 1

what are the three types of biological rhythms?

Answer 1

• circadian rhythms
• ultradian rhythms
• infradian rhythms

Question 2

what are biological rhythms?

Answer 2

• distinct patterns of change in body activity than conform to cyclical time periods
• influenced by internal body clocks and external changes to the environment
• regulated by endogenous pacemakers and exogenous zeitgebers

Question 3

what are endogenous pacemakers?

Answer 3

• the body’s internal biological clock
• mechanisms within the body that govern the internal biological bodily rhythms
• e.g. suprachiasmatic nucleus

Question 4

what are exogenous zeitgebers?

Answer 4

• environmental cues that help regulate the biological clock
• e.g. light and sound

Question 5

what are circadian rhythms?

Answer 5

• 24 hour cycles
• e.g. the sleep / wake cycle
• feeling tired at night and awake during the day demonstrates the effect of daylight as an important exogenous zeitgeber

Question 6

siffre’s cave study

Answer 6

• siffre had spent several extended periods in a cave to study the effects on his own biological rhythms
• deprived of exposure to natural light but access to adequate food and drink
• had artificial light to navigate within the cave

Question 7

siffre’s findings

Answer 7

• his biological rhythm was just beyond 24 hours (25-30)
• he continued to fall asleep and wake up on a regular schedule
• lost track of how many days he’d spent in the cave
• suggests the natural sleep / wake cycle may be slightly longer than 24 hours
• exogenous zeitgebers are vital for keeping the 24 hour cycle