biopsychology - endogenous pacemakers n exogenous zeitgebers.

Question 1

What is meant by endogenous pacemakers?

Answer 1

Mechanisms within the body such as the internal body clocks.

Question 2

What is meant by suprachiasmatic nucleus (SCN)?

Answer 2

Tiny cluster of cells that maintains the circadian rhythm and controls other biological rhythms.

Question 3

Where is the SCN located?

Answer 3

The hypothalamus of both hemispheres.

Question 4

What is the nature of the SCN?

Answer 4

• primary endogenous pacemaker in mammalian species.
• master clock.
• nerve fibres are connected to the eye cross in area called the optic chiasm on their way to the visual area of the cerebral cortex.
• lies above the optic chiasm where it receives information about light.
• continues even with eyes closed allowing our biological rhythm to adjust even when we sleep.

Question 5

What was the aim of the decoursey et al research (2000)?

Answer 5

Influence SCN has on chipmunks.

Question 6

What was the procedure of the decoursey et al research (2000)?

Answer 6

1. destroyed the SCN in 30 chipmunks.
2. returned them to their natural habitat for 80 days.

Question 7

What was the finding of the decoursey et al research (2000)?

Answer 7

Most had been killed as their sleep/wake cycles was destroyed (awake and restless) so their predators were able to find them.

Question 8

What was the conclusion of the decoursey et al research (2000)?

Answer 8

No SCN means no biological rhythms.

Question 9

What was the aim of the ralph et al research (1990)?

Answer 9

Influence of SCN has on hamsters.

Question 10

What was the procedure of the ralph et al research (1990)?

Answer 10

1. took the SCN out of genetically abnormal hamsters with a circadian cycle of 20 hours.
   - translated them into hamsters with the usual 24 hour cycle.

Question 11

What was the finding of the ralph et al research (1990)?

Answer 11

Normal hamsters cycles shortened to 20 hours.

Question 12

What was the conclusion of the ralph et al research (1990)?

Answer 12

SCN is key in establishing a sleep/wake cycle.

Question 13

What is the function of the pineal gland?

Answer 13

Receives signals from SCN directing it to increase production and secretion of melatonin at night and decrease it as light levels increase in the morning.

Question 14

What is meant by exogenous zeitgebers?

Answer 14

External environmental cues such as light and social cues that help regulate our biological rhythms.

Question 15

What would happen of we had no exogenous zeitgebers?

Answer 15

Our free-running biological clock continues to tick.

Question 16

What is the link between light and the SCN?

Answer 16

• receptors in the SCN are sensitive to changes in light levels during the day and use this information to help synchronise activity.
• can reset the body’s endogenous pacemaker.

Question 17

What was the aim of the campbell and murphy research (1998)?

Answer 17

Investigated how powerful light is as an exogenous zeitgeber and whether it can be detected any other way besides the eye.

Question 18

What was the procedure of the campbell and murphy research (1998)?

Answer 18

15 participants were woken at various times with light being shone at the back of their knees.

Question 19

What was the finding of the campbell and murphy research (1998)?

Answer 19

Changes in the sleep/wake cycle of up to 3 hours.

Question 20

What was the conclusion of the campbell and murphy research (1998)?

Answer 20

Light is a powerful zeitgeber but we do not need to enter our eyes to influence our brain and SCN.

Question 21

What was the conclusion of the campbell and murphy research (1998)?

Answer 21

Light is a powerful zeitgeber but we do not need to enter our eyes to influence our brain and SCN.

Question 22

What is meant by social cues?

Answer 22

Social stimuli such as meal times and social activities.

Question 23

What does aschoff et al (1971) believe about social cues?

Answer 23

Individuals can compensate for the absence of zeitgebers like natural light by responding to social zeitgebers.

Question 24

What does klein and wegmann (1974) believe about social cues?

Answer 24

Air travellers’ circadian rhythms can be adjusted more quickly if they go outside more at their destination as they would be exposed to the social cues of the new time zone.

Question 25

What is the link between social cues and babies?

Answer 25

• sleep/wake cycle in infants is random but by 6 weeks circadian rhythm begins.
• by 16 weeks most babies are entrained.
• determined by parents.

Question 26

How may social cues help with jet lag?

Answer 26

Rather than responding to hunger and fatigue conforming to local times for sleeping and eating will train your circadian rhythm.

Question 27

What is a strength of endogenous pacemakers and exogenous zeitgebers?

Answer 27

Practical application to help avoid jet lag.

Question 28

What are the weaknesses of endogenous pacemakers and exogenous zeitgebers?

Answer 28

• too simplistic to suggests that suprachiasmatic nucleus is the only endogenous pacemaker
  ↳ there are other complex influences on circadian rhythms aside from the SCN.
• may be an interactionist system.
• there is case study evidence challenging the role of exogenous zeitgebers implying that social cues alone are not effective in resetting the biological rhythms.