10- circadian rhythms

Question 1

define biological rhythms

Answer 1

cyclical changes in physiological systems

Question 2

what are the 3 types of biological rhythms

Answer 2

• circadian
• ultradian
• infradian

Question 3

how long are circadian rhythms

Answer 3

• last 24 hours

- optimise an organism’s physiology and behaviour to meet demands of the day/night cycle

Question 4

what are circadian rhythms driven by

Answer 4

• the suprachiasmatic nuclei (SCN) in the hypothalamus

- this pacemaker must constantly beyeset so our bodies are in synchrony with the outside world

Question 5

what is photoentrainment

Answer 5

• process of natural light providing input to set the SCN to the right time
• this information is then used to coordinate activity throughout the body

Question 6

what external signals determine the sleep-wake cycle

Answer 6

light and darkness

Question 7

when do our strongest sleep drives occur

Answer 7

2am-4am

1pm-3pm

Question 8

what does the body produce when it is dark

Answer 8

• release of melatonin from the pineal gland peaks during darkness
• light surpasses the production of melatonin

Question 9

what does melatonin do

Answer 9

induces sleep by inhibiting the neural mechanism that promote wakefulness

Question 10

how does homeostatic control of the sleep-wake cycle work

Answer 10

• when awake for a long time, homeostasis tells us the need for sleep is increasing due to energy used up
• this drive for sleep increases throughout the day and reaches maximum in the late evening

Question 11

how long can the internal circadian rhythm maintain a cycle even without natural light

Answer 11

24-25 hours

Question 12

positive evaluation of circadian rhythms (1)

Answer 12

+ practical application = chronotherapeutics (medication that gets released in the target area at the right time e.g greatest risk of heart attack is early morning)

Question 13

negative evaluation of circadian rhythms (4)

Answer 13

• research hasn’t isolated people from artificial light (a participants circadian rhythm was changed to 22 hours and up to 28 hours)
• individual differences in length (vary from 13-165h)
• individual differences in when peak is reached (morning people and evening people)
• temperature controls our body clock as SCN converts light to neural messages which change body temp and set timing of cells)