Biological Rythms

Question 1

biological rhythms

Answer 1

biological rhythms refer to cycles in biological or psychological activity that occur over a certain amount of time

Question 2

types of biological rhythms

Answer 2

1. circadian rhythms (once every 24h)
2. infradian rhythms (less than once every 24h)
3. ultradian rhythms (more than once every 24 hours)

Question 3

mechanisms involved in controlling biological rhythms

Answer 3

1. endogenous pacemakers
2. suprachiasmatic nucleus (SCN)
3. exogenous

Question 4

endogenous pacemakers

Answer 4

internal biological ‘clocks’ that allow organisms to control their internal rhythms

as a result, they set a natural ‘free-running’ rhythm in specific biological or psychological processes

Question 5

suprachiasmatic nucleus (SCN)

Answer 5

SCN is seen as the main endogenous pacemaker in the sleep-wake cycle

it is a tiny cluster of neurons located in the hypothalamus in the brain implicated in maintaining bodily rhythms

SCN can receive info about light levels and respond to this external cue to keep the rhythm in synchrony with the environment

Question 6

exogenous zietgebers

Answer 6

literally means ‘external time-givers’

refers to any external cue that may influence or ‘entrain’ our biological rhythms (endogenous pacemakers)

eg temperature, light, noise, clock

Question 7

role of endogenous pacemakers in the control of circadian rhythms

Answer 7

a circadian rhythm is a cycle in biological or psychological activity that occurs once every 24 hours

eg, sleep wake cycle occurs once every day

eg hormone production: melatonin (induces sleepiness) and growth hormone (build and restore the body) both peak at midnight, whereas cortisol (stress related) lowest at midnight

main endogenous pacemaker is the suprachiasmatuc nucleus (SCN); tiny cluster of neurons located in the hypothalamus in the brain implicated in maintaining bodily rhythms

SCN causes the pineal gland to secrete melatonin which makes us feel sleepy; controls the sleep-wake cycle

Question 8

role of exogenous zeitgebers in the control of circadian rhythms

Answer 8

thought that CRs such as the sleep wake cycle are also influenced by exogenous zeitgebers which are external time keepers such as light, temperature, noise

the SCN can respond to light (EZ), however without light the SCN still controls a rise and fall of melatonin

social cues also act as EZs as mealtimes are usually set around the same time of the day as well as exercise and work schedules

suggests both endogenous and exogenous factors play role in controlling these rhythms but to different degrees