Biologic Rhythms

Question 1

Define Biological rhythms

Answer 1

Body Rhythms are biological processes that show cyclical variation over time

Question 2

Define Circadian

Answer 2

Around 24 Hours, it is the sleep/wake cycle

Question 3

Define Endogenous Pacemaker

Answer 3

Internal Clock

Is spontaneously generated from an indivuduals internal state.

Question 4

Define Exogenous Zeitgeber

Answer 4

External Factors

Light levs such as sun night and day as well as clocks tells the time of day.

Question 5

Explain Circadian Rhythms

Answer 5

Often referred to as the “body clock,” the circadian rhythm is a cycle that tells our bodies when to sleep, rise, eat—regulating many physiological processes. This internal body clock is affected by environmental cues, like sunlight and temperature

Question 6

The Role Of The Suprachiasmatic Nuceaus in The Sleep/Wake Cycle

Answer 6

Light enters the retina even when eyes are closed.
Information sent via neural pathway to the SC.
The SCN is located in the hypothalamus.
Information is then sent via another neural pathway to the pineal gland.
The pineal gland is located deep within the brain.
Low light cues are detected in the SCN which triggers the pineal gland to release melatonin
Levels of melatonin rise
Sleep

Question 7

The Role Of The Suprachiasmatic Nucleus

Answer 7

Melatonin is released by the Pineal gland in the absence of light cue, but the circadian cycle disappears if the SCN is destroyed.

Question 8

Sleep Study - Siffre

Answer 8

Michel Siffre (1972) was a french cave explorer 
He spent Seven months underground with no cues as to the time of day
He organised his life into a fairly normal pattern of alternating periods of activity and sleep
He was linked upto a computer and video camera, to scientists on the surface, to monitor his physiological functions and state of mind 
For every day that passed he rose an hour later, the clock in his brain was running a little slower. He developed a 2 hour day (Not 24H)

Question 9

What does the study of Siffre suggest about biological rhythms?

Answer 9

Physical activity (Sleep/Wake) providing support for endogenous

Question 10

What does the study of Siffre suggest about biological rhythms?

Answer 10

Physical activity (Sleep/Wake) providing support for endogenous pacemaker.
Exogenous Zeitgeber can influence pacemaker

Question 11

Evaluation of Siffre Study

Answer 11

• Case Study:
• Rich Data
• Individual Differences
• Cant Generalise
• Control Environment:
• Control Extraneous variables
• Establish Cause and Effects

Lacks Mundane Realism

Question 12

The Tale Of The Mutant Hamsters

Answer 12

There is strong evidence for the importance of the SCN in maintaining the circadian rhythm.
When the SCN cells are removed from the brin and kept in the laboratory, they follow a cycle of neural activity lasting approximately 24.5 hours.

Breds of mutant Hamsters with a 20 hour rhythm had transplanted SCN cells from normal hamster foetuses who were born displaying the mutant 20 hour cycle. They also transplanted normal SCN tissue into the mutant hamsters who started to sow a 24 hour cycle within a week.

Question 13

Practical Application To Shift Work

Answer 13

Night workers engaged in shift work experience a period of reduced concentration around 6 in the morning meaning mistakes and accidents are more likely.

Research into the relationship between shift work and poor health show shift workers are three times more likely to develop heart disease, which may be due to the stress of adjusting to different sleep/wake patterns and the lack of poor quality of sleep.

Thus, research into the sleep/wake cycle may have economic implications in terms of how best to manage worker productivity.

Question 14

Weakness of Circadian Rhythms - Individual Differences

Answer 14

A case for individual differences in circadian rhythms. Morning people preferred to rise early and go to bed early (6am and 10pm) while evening people prefer going to sleep and wake up late (10am and 1am) showing peoples circadian rhythms could vary from one another.

Question 15

Real World Application

Answer 15

One real world application of circadian rhythms is chronotherapeutics - the study of how timing affects drug treatments.

The specific time that patients take their medication is very important as it can have a significant impact on treatment success. It is essential that the right concentration of a drug is released in the target are of the body at the time that the drug is most needed.

For example, the risk of heart attack is greatest during the early morning hours after awakening, and so chronotherapeutic medications have been developed with a novel drug delivery system. These medications can be administered before the person goes to sleep at 10pm, but the actual drug is not released until the vulnerable period of 6am to noon.

Question 16

Discuss and Research Into The Circadian Rhythm

Answer 16

A01:
Sleep Wake Cycle - Example of Circadian Rhythm) 
SCN - Endogynous pace maker
A03:
Mutant Hamster 

A01:
Outline Siffre's Research
A03:
Evaluation of Siffre:
Sample Bias,
Individual Differences

Question 17

Define Infradian Rhythms

Answer 17

an infradian rhythm is a rhythm with a period longer than the period of a circadian rhythm

Question 18

Two Examples of Infradian Rhythms

Answer 18

Menstrual Cycle

Hibernation

Question 19

Endogenous Pacemaker and the Menstrual Cycle

Answer 19

The Pituitary Gland governs the phrases of the menstrual cycle by influencing changes in the endometrium (Wall of the uterus)

Question 20

Briefly Explain the Hormones in the menstrual cycle

Answer 20

The hormone LH causes the mature egg to be released from the ovary. This image shows how the level of oestrogen changes during the menstrual cycle. Progesterone is another hormone secreted by ovaries: it maintains the lining of the uterus and stays high during pregnancy.

Question 21

Explain Pre-Menstrual Syndrome

Answer 21

is used to describe a variety of behavioural and emotional effects which occur at several phases of the cycle.

PMT occurs in all cultures suggesting a physiological cycle rather than an environmental influence.

Question 22

Deterministic View - Infradian Rhythm

Answer 22

Ms. English Drove a car into her husbands house, and blamed it on PMS. Supported by Dr Katherina who said ‘Women are not responsible for their actions on PMS’

Question 23

Free Will View- Infradian Rhythms

Answer 23

One Study Found people who were told to wake up earlier had higher levels of the stress hormone ACTH, which contributes to them waking up, causing them to wake earlier

Question 24

Research Into Exogenous Zeitgebers - Russell (1980)

Answer 24

It was found that female menstrual cycles became synchronised with other females through odour exposure.

In one study, sweat samples from one group of women were rubbed onto the upper lip of another group. Despite the fact that the two groups were separate, their menstrual cycles synchronised.

This suggests that the synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them.

These findings indicate that external factors must be taken into consideration when investigating infradian rhythms and that perhaps a more holistic approach should be taken, as opposed to a reductionist approach that considers only endogenous influences.

Question 25

Explain How Pheromones influence the menstrual cycle

Answer 25

Research has shown that when several women live in a house together and they are not taking oral contraceptives they tend to fall in line with each other and menstruate at the same time.

This is thought to be due to pheromones being released which are chemicals scents given off by each person

We unconsciously detect these chemicals which are secreted at certain times in the cycle.

Question 26

Strength Of Siffres Study

Answer 26

A strength of Siffre’s study is that he used an experimental approach. Siffre controlled the exogenous zeitgebers such as light and this allows causal relationships to be established.

Question 27

Weakness to Siffres Study

Answer 27

Siffre’s study was a case study, which focused on one individual person. Therefore, the results can’t be generalised to the wider population, as it doesn’t account for individual differences.

Question 28

Another Weakness of Siffres Study

Answer 28

Another weakness is that Siffre’s study only accounts for biological influences on the circadian rhythm and so only represents the nature side of the nature-nurture debate. This provides an unrealistic view of human behaviour because in real life both nature and nurture interact with one another.

Question 29

Define Hibernate

Answer 29

(of an animal or plant) spend the winter in a dormant state.

(of a person) remain inactive or indoors for an extended period.

Question 30

Why do some animals hibernate

Answer 30

During the cold winter months, nothing seems more inviting than a warm bed. But for some animals, hunkering down in a cozy den when nights are long and temperatures are low isn’t just a matter of temporary comfort — it’s necessary for survival.

Question 31

Define Seasonal Affective Disorder

Answer 31

Seasonal affective disorder (SAD) is a type of depression that’s related to changes in seasons — SAD begins and ends at about the same times every year. If you’re like most people with SAD, your symptoms start in the fall and continue into the winter months, sapping your energy and making you feel moody

Question 32

Explain Light Therapy

Answer 32

Because winter depression may be caused by a reaction to a lack of sunlight, broad-band light therapy is frequently used as a treatment option. This therapy requires a light box or a light visor worn on the head like a cap.

When light therapy is sufficient to reduce symptoms and to increase energy level, the individual continues to use it until enough daylight is available, typically in the springtime.

Question 33

Reason for Seasonal Affective Disorder

Answer 33

The cause for SAD is unknown. One theory is that it is related to the amount of melatonin in the body, a hormone secreted by the pineal gland. Darkness increases the body’s production of melatonin, which regulates sleep. As the winter days get shorter and darker, melatonin production in the body increases and people tend to feel sleepier and more lethargic.