Biopsychology

Question 1

What is the central nervous system?

Answer 1

The central nervous system consists of the brain and the spinal cord. It is responsible for the control of behaviour and regulation of the body’s physiological processes.

To do this, the brain must be able to receive information through the sensory receptors (eyes, nose, etc) and be able to send messages to the muscles and glands of the body in response.

Question 2

What are the four main areas of the brain?

Answer 2

• Cerebrum: The largest part, contains 4 lobes and split down the middle to the left and right hemisphere.
• Cerebellum: Responsible for motor skills, balance and coordinating the muscles.
• Dincephalon, which consists of:
  Thalamus, which regulates consciousness, sleep and alterness
  Hypothalamus, which regulates body temperature, stress, hunger and thirst
• Brain stem - Regulates breathing and heart rate.

Question 3

What is the spinal cord?

What happens if the spinal cord is damaged?

Answer 3

The spinal cord relays information between the brain and the rest of the body. This allows the brain to monitor and regulate bodily processes, such as digestion and breathing, as well as co-ordinate voluntary movement.

The spinal cord is connected to different parts of the body via pairs of spinal nerves which connect to specific muscles and glands; if the spinal cord is damaged, body areas connected to it by nerves below the damage will be cut off and stop functioning.

Question 4

What is the peripheral nervous system?

Answer 4

The peripheral nervous system is located outside the brain and spinal cord. It transmits messages via neurons (nerve cells) to and from the central nervous system.

It is divided into the somatic and the autonomic nervous system.

Question 5

What is the somatic nervous system?

Answer 5

The somatic nervous system is a division of the peripheral nervous system. It is responsible for controlling voluntary movements and conscious actions.

It connects the senses with the central nervous system and has both sensory and motor pathways. It controls skeletal muscles and is controlled by the motor cortex.

Question 6

What is the autonomic nervous system?

Answer 6

The autonomic nervous system is a division of the peripheral nervous system. It is responsible for controlling involuntary movements.

It has only motor pathways and controls smooth muscles and the internal organs and glands of the body. It is controlled by the brain stem.

The autonomic nervous system is further divided into the:

• Sympathetic nervous system, activates the flight or fight response when a person is stressed.
• Parasympathetic nervous system, activated when the body is relaxing and conserving energy.

Question 7

What is a neuron?

Answer 7

Neurons are specialised nerve cells that move electrical impulses to and from the Central Nervous System.

Question 8

What are the 7 different parts of a neuron?

Answer 8

• Cell body: Controls the centre of the neuron
• Nucleus: Contains genetic material
• Dendrites: Receives an electrical impulse (action potential) from other neurons or sensory receptors (eyes, nose, etc)
• Axon: A long fibre which carries the electrical impulse from the cell body to the axon terminal
• Myelin Sheath: Insulating layer that protects the axon and speeds up the transmission of the electrical impulse.
• Schwann Cells: Makes up the Myelin Sheath
• Nodes of Ranvier: Gaps in the Myelin Sheath - speeds up the electrical impulse along the axon.

Question 9

What are sensory neurons?

Answer 9

Sensory neurons are found in sensory receptors (eyes, nose, etc). They carry electrical impulses from the sensory receptors to the central nervous system via the peripheral nervous system.

These neurons convert sensory receptors into electrical impulses, and when these impulses reach the brain, they turn into sensations, such as heat or pain, allowing the body to react appropriately.

Some impulses terminate at the spinal cord, allowing for reflexes to occur quickly without waiting for the delay of waiting for the brain to respond.

Question 10

What are motor neurons?

Answer 10

Motor neurons are located in the central nervous system, but project their axons outside it. They send electrical impulses via long axons to the effectors (glands and muscles) so they affect function.

When motor neurons are stimulated they release neurotransmitters that bind the receptors on muscles to trigger a response, which leads to movement.

Question 11

What are relay neurons?

Answer 11

Relay neurons are found in the central nervous system and are responsible for connecting sensory neurons to motor neurons, allowing them to communicate with one another.

The relay neurons in the spinal cord are involved in the analysis of a sensation during a reflex arc, and decide how to respond without waiting for the brain to process the pain.

Question 12

What is synaptic transmission?

Answer 12

Synaptic transmission refers to when action potentials (electrical impulses) travel between a pre-synaptic neuron (the neuron transferring the action potential) and a post-synaptic neuron (the neuron recieving the action potential)

When the action potential reaches the pre-synaptic terminal, a process called exocytosis occurs: this is when chemical messengers known as neurotransmitters are released from sacs on the pre-synaptic membrane known as vesicles. This neurotransmitter diffuses accross the synaptic cleft (a gap between the post and pre synaptic membrane) where it binds to post-synaptic receptor sites.

Question 13

What is re-uptake?

Answer 13

Re-uptake is the process which terminates synaptic transmission after a fraction of a second.

This is when the neurotransmitter is taken aback by the vesicles on the pre-synaptic neuron where they are stored for later release. The quicker the neurotransmitter is taken back the shorter the effects.

Question 14

What are the two types of neurotransmitters?

What determines the likelihood of a neuron firing an impulse?

Answer 14

• Excitatory Neurotransmitters: causes an excitatory post-synaptic potential, meaning the post-synaptic neuron is more likely to fire an impulse.
• Inhibitory Neurotransmitters: causes an inhibitory post-synaptic potential, meaning the post-synaptic neuron is less likely to fire an impulse.

The likelihood that a neuron fires an impulse is determined by adding up the excitatory and inhibitory synaptic input. If the net effect is inhibitory, the neuron will not fire an impulse. If the net effect is excitatory, the neuron will fire an impulse.

Question 15

What is the direction of synaptic transmission?

Answer 15

Diffusion of the neurotransmitters means they can only go from a high to low concentration, meaning synaptic transmission only happens in one direction: from the pre-synaptic membrane to the post-synaptic membrane.

This is because the vesicles containing neurotransmitters are only present at the pre-synaptic membrane, and the receptors containing neurotransmitters are only present in the post-synaptic membrane, and the binding of the neurotransmitter to the receptor enables information to be transmitted to the next neuron.

Question 16

How do psychoactive drugs work?

Answer 16

Psychoactive drugs, such as SSRIs, work by affecting the transmission of neurotransmitters across the synapse.

Question 17

How do pain medications work?

Answer 17

Some pain medications mimic the effect of inhibitory neurotransmitters by making the post-synaptic membrane less likely to fire, and therefore inhibit an action potential from occuring. This reduces brain activity, leading to less pain.

Question 18

What is the endocrine system?

Answer 18

The endocrine system produces and secrete hormones into the bloodstream which are required to regulate many bodily functions. The major glands include the pituitary gland and the adrenal gland, where each gland produces different hormones which regulate activity of organs/tissue in the body.

Hormones come into contact with most cells in the body, but they only affect a limited number of cells known as target cells. These respond to a particular horomone because they contain receptors for that hormone. There is a physiological reaction when enough receptor sites are stimulated by that hormone.

Question 19

What is the pituitary gland?

Answer 19

The pituitary gland is located in the brain, and it produces hormones whose primary function is to influence the release of other hormones from other glands in the body.

It is controlled by the hypothalamus, where a signal in the form of a releasing hormone is sent to the pitutary gland. This causes the pituitary gland to send a stimulating hormone into the bloodstream to tell the target gland to release its hormone. As this hormone rises, production of the stimulating and releasing shuts down.

Question 20

What are the two divisions of the pituitary gland?

Answer 20

• The anterior pituitary gland: releases ACTH which regulates levels of cortisol.
• The posterior pituitary gland: releases oxytocin, crucial for infant/mother bonding.

Question 21

What are the two parts of the adrenal gland?

Answer 21

The adrenal cortex is the outer section of the adrenal gland. It produces the hormone cortisol during chronic (long term) stress.

The adrenal medulla is the inner section of the adrenal gland. It produces the hormone adrenaline during acute (sudden) stress. This causes the fight or flight response.

Question 22

What happens during and after the flight or flight response?

Answer 22

The hypothalamus triggers the sympathetic nervous system and sends a signal to the adrenal medulla, which releases the hormone adrenaline.

Adrenaline increases heart rate, constricts blood vessels, increases the rate of blood flow, raises blood pressure, increases respiration and increases blood supply to the brain (for rapid response planning) and skeletal muscles (for physical action).

One the threat has passed, the parasympathetic nervous system dampens down the stress response, slowing down heartbeat and reducing blood pressure.

Question 23

What are 2 strengths and 2 weaknesses of the fight or flight response?

Answer 23

Strengths:

• Studies show that those with malfunctioning adrenal glands do not have a normal fight or flight response, showing the importance of adrenaline.
• This makes sense from an evolutionary perspective, as it would have helped an individual survive by fighting or fleeing a threat.

Weaknesses:

• Gray (1998) argues that the first response to stress is not fight or flight but rather to freeze.
• Taylor (2000) found that females respond with the tend and befriend response, as they have the hormone oxytocin. Von Dawans (2012) argued that men also tend and befriend, such as during 9/11.

Question 24

What is localisation of function?

Answer 24

Localisation of function is the theory that functions (such as vision or hearing) have specific locations within the brain. This could be extremely localised to particlar areas of the brain or more widespread to several parts of the brain.

Question 25

What is the visual cortex?

Answer 25

The visual cortex processes information such as colour and shape - it is located in the occipital lobe in both hemispheres of the brain.

Visual processing starts in the retina, where light enters and strikes the photoreceptors. Nerve impulses from the retina are transmitted to the brain via the optic nerve.

The majority of these terminate in the thalamus, which acts as a relay station, passing the information onto the visual cortex.

Question 26

What is the auditory cortex?

Answer 26

The auditory cortex processes information such as pitch and volume - it is located in the temporal lobe in both hemispheres of the brain.

Auditory processing begins in the cochlea in the inner ear, this is where soundwaves are converted into nerve impulses. These travel via the auditory nerve into the auditory cortex.

Basic decoding occurs in the brain stem, and the thalamus carries out further processing before the impulses reach the auditory cortex.

Question 27

What is the motor cortex?

Answer 27

The motor cortex is responsible for voluntary movements - it is located in the frontal lobe of both brain hemispheres.

Different parts of the motor cortex control different parts of the body - these areas are arranged logically next to each other.

Damage to this area can cause a loss of muscle function or paralysis on either or both sides of the body, depending on the hemisphere(s) damaged.

Question 28

What is the somatosensory cortex?

Answer 28

The somatosensory cortex is responsible for processing sensations such as pleasure or pain. It is located in the parietal lobe of both hemispheres.

Question 29

What is Broca’s area?

Answer 29

Broca’s area is located in the left hemisphere of the frontal lobe.

Paul Broca found that damage to this area causes expressive aphasia, a disorder which affects language production but not understanding. Those with expressive aphasia have difficulty producing speech.

Question 30

What is Wernicke’s area?

Answer 30

Wernicke’s area is located in the left hemisphere of the temporal lobe.

Carl Wernicke found that damage to this area causes receptive aphasia. This disorder leads to an imparied ability to understand language. Those with receptive aphasia could speak fluently but could not understand language.

Question 31

What are 3 weaknesses of localisation of function theory?

Answer 31

• Lashley’s equipotentiality theory states that higher mental functions are not localised, and intact areas of the cortex take over responsibility for a specific cognitive function following injury to the area normally responsible
• Dronkers et al (2007) re-examined the preserved brains of Broca’s patients, discovering that several areas of the brain had been damaged, suggesting that damage to the Broca’s area causes temporary, but not severe speech disruption, suggesting it is more widely localised than thought.
• Bavelier et al. (1997) found that there are individual differences in which brain areas are responsible for certain function. When a person is engaged in silent reading, the right temporal, left frontal and occipital lobe are all engaged.

Question 32

What is Hemispheric Lateralisation?

What is each hemisphere responsible for?

Answer 32

Hemispheric Lateralisation is the idea that certain functions are principally goverened by one side of the brain. In most people, language centres are lateralised to the left hemisphere, and the right hemisphere is dominant for visuo-spatial functions and facial recognition.

The right hemisphere is responsible for the left hand side of the body and the left hemisphere is responsible for the right hand side of the body. The two hemispheres are connected by the corpus callosum, a bundle of nerve fibres. Research suggests that the two hemispheres work together to form tasks.

Question 33

What are 2 strengths of hemispheric lateralisation?

Answer 33

• Hemispheric lateralisation makes sense from an evolutionary perspective, allowing one hemisphere to be free if the other is engaged in a task - this is supported by Rogers et al (2004) who found that hemispheric lateralisation in chickens is associated with an ability to perform two tasks simultaneously, those being finding food and being vigilant for predators.
• Patients with damage to their left hemisphere can experience global aphasia; this suggests that language is lateralised to the left hemisphere.

Question 34

What are 2 weaknesses of hemispheric lateralisation?

Answer 34

• A split brain patient known as JW developed the capacity to speak using his right hemisphere, although more fluent if information was presented in his left visual field. This shows that language is not entirely lateralised to the left hemisphere.
• Danelli et al (2013) reported on EB, a child with his left hemisphere removed at 2 years old due to a tumor. His language appeared normal in everyday life, despite subtle grammatical problems and below average scores on picture naming. This suggests that language function can be preserved after the removal of the left hemisphere, although the right hemisphere cannot provide it perfectly by istelf.

Question 35

Who are split-brain patients?

Answer 35

Split-brain patients are those who have cut the corpus callosum in order to prevent the violent electrical activity caused by epileptic seizures crossing from one hemisphere to another.

Question 36

How did Sperry and Gazzaniga (1968) investigate split-brain patients?

Answer 36

Split-Brain patients were asked to stare at a dot in the centre of a screen, where information would be presented in either the left or right visual field, and then asked to respond.

Information in the right visual field were only able to be expressed verbally, however information in the left visual field could only be drawn. This is because information in the left visual field would be processed by the right hemisphere, which has no language centres, and information in the right visual field would be processed by the left hemisphere, where the language centres are located, and there is no communication between the two hemispheres due to the severed corpus callosum.

Question 37

What are 2 strengths of split-brain research?

Answer 37

• Split-brain research has enabled discoveries of hemispheric lateralisation.
• Experiments on split-brain research are highly controlled and scientific.

Question 38

What are 2 weaknesses of split-brain research?

Answer 38

• The data from Sperry and Gazaniga is very artificial, as a severed corpus callosum can be compensated for by the unrestricted use of both visual fields. This means the research lacks ecological validity.
• Split-brain patients went through drug therapies due to their epilepsy, which may affect the way their brain works, therefore, the findings of split-brain research may not be generalisable to the general population.

Question 39

What is brain plasticity?

Answer 39

Brain plasticity refers to the brain’s ability to change and adapt as a result of experience, allowing the brain to cope with the indirect effects of brain damage or inadequate blood supply to the brain.

Question 40

How does life experience affect plasticity?

What research evidence suggests that life experience affect plasticity?

Answer 40

Nerve pathways that are used frequently develop stronger connections, and those that are rarely used eventually die. The brain is able to adapt to a changing environment by developing stronger connections and killing weak ones. There may be a decline in cognitive function with age.

An example of life experience affecting plasticity is seen with Boyke et al. (2008) taught 60 year olds how to juggle, which increased grey matter in the visual cortex.

Question 41

What research evidence suggests that video games affect plasticity?

Answer 41

Kuhn et al. (2014) compared a control group to a group who had been given video game training for at least 30 minutes for 2 months on Super Mario.

They found that playing videogames caused a significant increase in grey matter in the visual cortex, hippocampus and cerebellum, as well as resulting in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance.

Question 42

What research evidence suggests that meditation affect plasticity?

Answer 42

Davidson et al. (2004) compared 8 practitioners of Tibetan medication with 10 students who had no previous mediation experience. He found that there was greater neural activity in the practicioners, even before they had started meditating.

Question 43

What are 2 strengths of plasticity?

Answer 43

• Kempermann et al. (1998) found far more neurons in the brains of rats in complex environments compared to those housed in basic cages. This increase was most prominent in the hippocampus, which is involved in the forming of new long-term memories and the ability to navigate.
• Maguire et al. (2000) found that the hippocampus in taxi drivers were significantly larger than a control group, correlated to the time they had spent as a taxi driver.

Question 44

What is functional recovery?

Answer 44

Functional recovery is a form of plasticity. This is when the brain redistributes or transfers functions usually performed by damaged areas to other, undamaged areas. Recovery is more likely when the brain is still maturing, however, it is possible at any age.

Neural reorganisation refers to growth of new neurons to compensate for damaged areas, involving axon sprouting, where new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways.

Physiotherapy may be required to maintain improvements in functioning, as spotaneous recovery from a brain injury tends to slow down after a couple of weeks.

Question 45

What are 2 strengths of functional recovery?

Answer 45

• Phantom Limb Syndrome can be used as evidence of neural reorganisation. It is thought to be caused by neural reorganisation in the somatosensory cortex that occurs as a result of limb loss.
• Huben and Torten Wisel (1963) sewed one eye of a kitten shut and analysed the brain’s cortical response. The visual cortex for the shut eye was not idle, and it continued to process information from the open eye, showing that brain areas can reorganise themselves and adapt their functions.

Question 46

What are post-mortem examinations?

Answer 46

Post-mortem examinations are the analysis of behaviour following the death of an individual. Post-mortem studies have discovered a link between brain abnormalities and psychiatric disorders.

Question 47

What is a strength and 2 weaknesses of post-mortem examinations?

Answer 47

Strength:

• Allows for more detailed examination of anatomical and neurochemical aspects of the brain compared to other methods. Researchers have been able to examine deeper regions, such as the hippocampus and the hypothalamus.

Weaknesses:

• May lack validity, as people die in a variety of circumstances, and the length of time between death and post-mortem or drug treatments can all affect the brain.
• Post-Mortem studies have small sample sizes, as special permission needs to be granted. Therefore, the findings cannot be generalised to the wider population.

Question 48

What are FMRIs?

Answer 48

Functional Magnetic Resonance Imaging (FMRIs) provides an indirect measure of neural activity. It uses radio waves and magnetic fields to monitor blood flow in the brain, and it measures the change in energy released by haemoglobin, reflecting activity on the brain to give a moving picture. Activity in regions of interest can be compared during a base line task and during a specific activity.

Question 49

What are 2 strengths and 2 weaknesses of FMRIs?

Answer 49

Strengths:

• Can capture dynamic brain activity
• Good spatial resolution (smallest feature a measurement can detect)

Weaknesses:

• Poor temporal resolution (measurement with respect to time)
• Expensive, leading to reduced sample sizes, leading to low validity.

Question 50

What are EEGs?

Answer 50

An electroencephalogram (EEG) directly measures general neural activity in the brain. Electrodes are placed on the scalp, and they detect neuronal activity directly below where they are placed. When electrical signals are graphed over time, the resulting representation is called an EEG pattern. These patterns show spikes of electrical activity.

Question 51

What is one strength and 2 weaknesses of EEGs?

Answer 51

Strength:

• Useful in clinical diagnosis, such as in recording the neural activity associated with epilepsy so that the doctors can confirm the person is experiencing seizures.

Weaknesses:

• Cheap, meaning they can be used more widely
• Poor spatial resolution.

Question 52

What are ERPs?

Answer 52

Event related potentials (ERPs) are when electrodes are placed directly on the scalp and neural activity is directly measured in response to a specific stimulus introduced by the researcher.

ERPs may be difficult to pick out compared to other electrical activity happening in the brain, so a patient may have many presentations to the target stimulus, and the responses are averaged together. Extraneous neural activity not linked to the stimulus will not occur consistently, but activity linked to the stimulus will.

Question 53

What are 3 strengths and 2 weaknesses of ERPs?

Answer 53

Strengths:

• Can measure the processing of the stimulus even in the absence of a behavioural response, therefore possible to covertly measure the processing of a stimulus.
• Cheap
• Good temporal resolution

Weaknesses:

• Bad spatial resolution
• Difficult to measure activity deeper in the brain

Question 54

What are biological rhythms?

Answer 54

Biological rhythms are cyclical changes in physiological systems which evolved beause the environment organisms live in have cyclical changes.

Question 55

What are circadian rhythms?

Answer 55

Circadian rhythms are a type of biological rhythm. These are cycles that last for 24 hours.

They are driven by the suprachiasmatic nuclei in the hypothalamus. They must be constantly reset so that our bodies are in synchrony with the outside world.

The input to this system is natural light, which sets the suprachiasmatic nuclei to the correct time via photoentrainment. The SCN then coordinates activity of circadian rhythms throughout the body.

Question 56

What is the sleep-wake cycle?

Answer 56

The sleep-wake cycle is a circadian rhythm. This states that light and darkness are the external signals that determine when we feel the need to sleep and wake up.

During darkness, melatonin (the hormone which induces sleep) is at its peak, and during light, melatonin is supressed.

Furthermore, when we have been awake for a long time, homeostasis tells us that the need for sleep is increasing because of the amount of energy used for wakefulness. This drive increases gradually throughout the day, reaching its maximum in the late evening.

This circadian rhythm will last 24-25 hours, even without natural light.

Question 57

What is a strength of circadian rhythms?

Answer 57

Circadian rhythms have practical applications due to chronotherapeutics. This states that the time drugs are taken are important for treatment success. For example, heart attacks are most likely after just waking up, therefore, medications are taken at night but do not activate until the morning, where the patient is most vulnerable.

Question 58

What are 3 weaknesses of circadian rhythms?

Answer 58

• Cziesler et al. (1999) altered participant’s circadian rhythms using artifical light alone, suggesting it is not only natural light which affects circadian rhythms.
• There are individual differences: Cziesler et al. (1999) found that cycles can vary from 13 to 165 hours.
• Studies on those who live in arctic regions show that they have normal sleeping patterns despite the sun not setting in summer months, showing how light may not have great bearing on internal biological rhythms.

Question 59

What are ultradian rhythms?

Answer 59

Ultradian rhythms are a type of biological rhythm. These are cycles that last less than 24 hours, for example, the sleep cycle, where we show non rapid eye movement, then rapid eye movement in a cycle that repeats every 90 minutes.

Kleitman (1969) suggested that this 90 minute cycle continues when we are awake, where we progress through altertness and physiological fatigue; we can focus for 90 minutes but get tired towards the end of it.

Question 60

What is a strength and weakness for ultradian rhythms?

Answer 60

Strength:

• Ericcson et al. (2006) found that a group of elite violinists practiced for 90 minutes at a time, and napped to recover. This same pattern was found with writers, chess players and athletics, showing support for ultradian rhythms.

Weakness:

• Tucker et al. (2007) found that participants had different characteristics in terms of sleep duration and time taken to fall asleep, suggesting there are individual differences in ultradian rhythms.

Question 61

What are infradian rhythms?

Answer 61

Infradian rhythms are a type of biological rhythm. These are cycles that last for more than 24 hours, for example, the menstrual cycle, which lasts for approximately a month.

The menstrual cycle is regulated by hormones. Ovulation occurs halfway through where oestrogen levels are at their peak, which usually lasts for 16-32 hours. After ovulation, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus.

Question 62

What is a strength and weakness for infradian rhythms?

Answer 62

Strength:

• Penton-Voak (1999) found that women preferred feminine faces on men for long-term relationships, however, they preferred masculine faces during ovulation, showing how infradian rhythms can affect behaviour.

Weakness:

• Menstrual cycles synchronise in women living together. In one study, samples of sweat were collected from one woman and rubbed onto the upper lip of another woman, where their menstrual cycles then became synchronised. This suggests that the menstrual cycles are less affected by infradian rhythms and more by pheromones, a substancce released into the environment by an animal which affects the behaviour of other animals in the species.

Question 63

What are endogenous pacemakers?

Answer 63

Endogenous pacemakers refer to our internal biological rhythms. The most important endogenous pacemaker is the supachiasmatic nuclei, a cluster of nerve cells in the hypothalamus responsible for circadian rhythms.

Neurons within the SCN synchronise with each other so that their target neurons in sites elsewhere in the body recieve time coordinated signals, which maintain a circadian rhythm, albeit not for very long.

The SCN is also responsible for the manufacture and secretion of melatonin in the pineal gland, as it sends a signal to the pineal gland, directing it to increase production of melatonin at low light levels.

Question 64

What is a strength and weakness of endogenous pacemakers?

Answer 64

Strength:

• Folkard (1996) studied Kate Aldcroft who spent 25 days in a laboratory without any exogenous zeitgebers. It was discovered that her core temperature rhythm was at 24 hours, indicating we do not need exogenous zeitgebers.

Weakness:

• Kate Aldcroft’s sleep-wake cycle extended to 30 hours, suggesting that we do need the exogenous zeitgebers.

Question 65

What are exogenous zeitgebers?

Answer 65

Exogenous zeitgebers are outside cues responsible for biological rhythms.

Receptors in the supachiasmatic nuclei are responsible for synchronising the activity of the body’s organs and glands. Light resets the internal biological clock each day, keeping it on a 24 hour cycle.

When people travel to a country with a different time zone or move to a night shift, their endogenous pacemakers become out of sync with exogenous zeitgebers, therefore leading to disrupted sleep patterns.

Question 66

What are 2 strengths and 1 weakness of exogenous zeitgebers?

Answer 66

Strengths:

• Blind people with light perception have normal circadian rhythms, however, blind people without have abnormal circadian rhythms, showing the importance of outside factors.
• Burgees et al (2013) found that exposure to a bright light prior to an east-west flight decreased the time needed to adjust circadian rhythms to local time.

Weakness:

• Although the sun does not set in summer months in Arctic regions, individuals still show normal sleeping patterns, suggesting exogenous zeitgebers have little bearing on internal biological rhythms.