Biological Rhythms - Unit 3

Question 1

What research has been carried out to support external zeitgebers controlling menstrual cycle?

Answer 1

•Russell et al - group of woman pairs found to have synchronised cycles.

• Two woman pairs used. Daily samples of sweat taken from one + put on top lip of other
• Noted that there cycles became synchronised with ‘odour donor’. Assumed this is to do with strong pheromones (hormones) in sweat

•Weller - found that woman closer in relationship normally have increased synchronisation

•

Question 2

Outline the menstrual cycle…

Answer 2

• Controlled by the pituitary gland + driven by hormone oestrogen
• Average length is 28 days
• Lining breaks down first = mentrual bleeding
• Stimulated by gradually increasing amount of oestrogen - bleeding slows then stops
• About mid cycle, oestrogen surge = egg released (ovulation)
• After, hormone progesterone maintains thickness of lining or pregnancy + ^blood supply
• No pregnancy = both hormone levels decreases rapidly = uterus lining breaks down again

Question 3

How is SAD (seasonal effective disorder) controlled?

Answer 3

•Light (external zeitgeber) is lacking in winter = release of more melotonin by pineal gland

• melotonin leads to low levels of serotonin
• Low serotonin been linked to depression
• Low light = more melatonin = low serotonin = SAD

Question 4

Explain the difference between primary and secondary insomnia…

Answer 4

• Primary (chronic) insomnia is where symptoms last or more than a couple of months + there is no obvious underlying cause. Not related to other sleeping problem or other medical conditions e.g. depression
• Secondary insomnia is caused by a pre-exiting physiological or physical condition or sleep problem e.g. Sleep apnoea

Question 5

What are the causes of primary insomnia? A01

Answer 5

• Faulty neurotransmitters - e.g. Serotonin, noradrenalin, acetylcholine
• Inherited faulty GABA systems = GABA levels lower in insomniacs (Winkelman) - GABA switches off some parts of the brain
• Stress learnt- people try maladaptive ways to cope with insomnia, stress is not present any more
• predisposition to greater arousal - normally linked to idiopathic insomnia = hard to switch off waking mechanisms in brain
• Fault between raphe nuclei + reticular activating system (RAS)