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Biopsychology Revision:
The divisions of the nervous system: AO
Human nervous system is a body wide system of nerve cells that collect information from the world, processes this information and then acts by directing body organs and muscles via the transmission of electrochemical messages. CNS includes the brain for all conscious and unconscious processing and the spinal cord which receives and transmits information and some reflex processing. PNS is a body network of messenger neurones, sensory neurones take information to the CNS and motor neurones take information away from the CNS. Autonomic nervous system is the part that controls actions of internal glands in an involuntary system. Somatic nervous system is the part that controls skeletal muscles and is a voluntary system. Sympathetic system is part of the ANS and increases bodily activities and releases noradrenaline, activates in fight/flight response and increases heart, sweat and breathing rate.
Parasympathetic system is part of the ANS that decreases bodily activities and decreases heart, sweat and breathing rates. Homeostasis is maintained this means our internal environments is regulated by a balance between the sympathetic and parasympathetic systems. The Endocrine system AO1: The endocrine system is a collection of glands around the body that regulates bodily functions, growth and psychological factors. It acts by releasing chemical messengers called hormones into the blood. Pituitary gland which controls the release of hormones from other glands. Hypothalamus which is a hormone that links the nervous system to the endocrine system. Pineal gland releases melatonin that modulates the sleep pattern. Thyroid gland that releases thyroxine that modulates metabolism. Thymus gland that releases thymosin that stimulates the development of T-cells in the immune system. Pancreas which releases insulin that regulates blood sugar levels. Adrenal gland hat releases adrenaline that regulates the fight or flight response. Ovaries that release oestrogen and develops secondary sexual characteristics in females. Testes release testosterone and leads to the development of secondary sexual characteristics in males.
The action potential travels down the axon of the pre-synaptic neurone, this forces vesicle containing neurotransmitters to merge with the cell membrane and release neurotransmitters into the synaptic cleft. Receptors on the post-synaptic neurone’s dendrite membrane detects the presence of the neurotransmitters, changing the chemistry within the post-synaptic neurone. If the charge inside the post-synaptic neurone passes a threshold a new action potential forms and the message is passed on. The neurotransmitter detaches from the receptors and return to the pre-synaptic cell via transport proteins, this is called reuptake. Excitation is when excitatory neurotransmitters increase the likelihood of a new action potential forming in the post synaptic cell. When detected by receptors the electrical charge inside becomes more positive and likely to fire, this is called depolarisation. Inhibition is when inhibitory neurotransmitter decreases the likelihood of a new action potential forming in the post-synaptic cell. When detected by receptors the electrical charge inside becomes more negative and less likely to fire, this is called hyperpolarisation. Summation is the combined effect of all inhibitory and excitatory influences, resulting in a new action potential forming or not. Uni-directional is when information can only be passed between the pre- synaptic and post- synaptic neurones in one direction. The fight or flight Response: AO The fight or flight response is an evolutionary survival mechanism in response to a threat, it primes the body and mind for extreme action, such as fighting for our life or escaping a threat. In a fight or flight response, a stressor is first detected by hypothalamus, the HPA axis in the endocrine system is activated and the pituitary gland releases the hormone ACTH then is detected by the adrenal cortex, releasing cortisol, the hypothalamus also
activates the sympathetic branch of the ANS, and the adrenal medulla is triggered via the sympathetic adrenomedullary pathway releasing adrenaline. Adrenaline increases anxiety, attention and alertness and the physical effects of adrenaline include increases blood flow to the brain and skeletal muscles and decreases blood flow to the skin and the digestive and immune system. The fight or flight response AO3: The SRY gene found on the male Y chromosome, directs male development, promoting aggression and resulting in the fight or flight response. The SRY gene respond to stress by releasing adrenaline and increased blood flow to organs in the fight or flight responses. In contrast, the absence of the SRY gene in females may prevent this response and lead to the “tend and befriend response.” Females tend to show a “tend and befriend response” rather than a “fight or flight response”, this involves protecting themselves and their young through nurturing behaviours and protective alliance with other women. Women’s responses evolved in the context of primary caregiver of their children, fleeing at any sign of danger would put a female’s offspring at risk. Localisation of function in the brain: AO Localisation of function refers to the belief that specific areas of the brain are associated with specific cognitive processes. Motor cortex is responsible for the generation of voluntary movements. Somatosensory is receiving sense impressions from around the body. Broca’s area is in the left frontal lobe and is responsible for speech production.
alone can cause temporary speech disruption, they do not usually result in severe disruption of spoken language. This study suggests that language and cognition are far more complicated than once thought and involve networks of brain regions rather than being localised to specific areas. Modern brain scanning techniques like FMRI support research on language centres, this is because they show activation of regions when healthy participants perform a task. Lateralisation and split-brain research: AO Hemispheric Lateralisation is when the left hemisphere is responsible for language and speech and the right hemisphere for visual and motor tasks. The two hemispheres are connected by bundles of nerve fibres such as corpus callosum and exchange information. Split-brain research was when 11 epileptic patients who had the corpus callosum cut and they explored how each hemisphere responded to a task. They found that if a picture was presented to the left-visual field of a split-brain patient then information is processed by the right hemisphere, but it cannot respond verbally as it has no language centres. The left hemisphere does not receive information and therefore cannot talk about it, despite having language centre. Lateralisation and split-brain research AO3: The split-brain research is rarely carried out nowadays and many studies only include a few participants, these patients may have underlying physical disorders that made the split- brain procedure necessary or there may have been some intact nerve fibres remaining. This means the studies are not always replicated and may be unwise to draw general conclusions from them.
The experimental procedure used in split brain patients is unlike how these individuals would process information and act in normal day to day life, so this lacks mundane realism. Plasticity and Functional Recovery AO1: Brain Plasticity refers to the brain’s ability to modify its own structure, creating new neural pathways and pruning away weak connections as a result of experience. Functional recovery is when we recover abilities and mental processes that have been compromised as a result of trauma, when brain cells are damaged, other parts sometimes take over their functions. Plasticity and Functional Recovery AO3: Research support from a case study of taxi drivers, Maguire et al (2000) discovered that changes in the brain could be detected as a result of taxi drivers extensive experience of spatial navigation. The posterior hippocampi in the London taxi drivers were found to be significantly larger than the controls. Suggesting that the physical structure of the brain is plastic and able to reconfigure itself to adapt to psychological demands. Kempermann et al found that rats in a complex environment developed more neurons than rats housed in lab cages. They showed to be an increase in neurons in the hippocampi which is associated with the formation of new memories and the ability to navigate. This shows clear evidence of the brain’s ability to adapt as a result of experience. It is commonly accepted that functional plasticity reduces with age, and that adults with brain trauma require social support or must develop strategies to deal with cognitive deficits. However, studies have suggested that even abilities commonly thought to be fixed in childhood can be modified in adults with
Circadian Rhythms AO1: A circadian rhythm is a biological rhythm that lasts around 24 hours, we have a circadian rhythm for regulating sleep and wake cycle, the release of hormones and varying our body temperature and blood pressure. Environmental light levels cause neural signals to be sent to the SCN, so that the circadian rhythm can be synchronised with daylight hours. The free running internal circadian clock maintains a cycle of 24- hours even in the absence of cues. Circadian rhythm AO3: There is evidence for the free-running circadian rhythm. The French cave explorer Michel Siffre spent 6 months in a cave in Texas with no daylight, clocks or radio and his circadian rhythm settled to just over 24 hours, but with some dramatic variations. When he stayed underground at age 60, his circadian rhythm slowed down, sometimes stretching to 48 hours. This shows that the circadian rhythm is not dependent on light or social cues and can vary with age. Individual differences, this is because research has it the cycle can vary between 13 to 65 hours, this would explain why some people to rise early and go to bed early whereas others want to wake up and go to bed later. Has real world applications, from understanding how blue light from devices disrupt sleep, how to combat the effects of jet lag and shift work and understanding that circadian blood pressure rhythm helps with timing drug treatments.
Infradian and Ultradian AO1: Infradian rhythms are cycles with a duration longer than 24 hours such as the menstrual cycle, this can vary between 23 and 36 days, but averages 28 days. It is regulated by hormones and ovulation takes place halfway through. Another example of Infradian rhythms would be seasonal affective disorder, this is when emotional mood lowers in winter and improves in summer, and it is suspected this is due to lack of sunlight. Ultradian rhythms are cycles lasting less than 24 hours, such as sleep cycles. Sleep involves a repeating cycle of 90-100 minutes, with five stages including REM. During deep sleep, brainwaves slow down and breathing and heart rate slow down. Infradian and Ultradian AO3: Dermot and Kleitman used EEG to record the brain activity of 33 participants for one night’s sleep. Brain waves followed a cyclic activation pattern, with bodily relation during slow-wave sleep and rapid eye movement during periods of high activation. This supports the theory that the stages of sleep are an Ultradian rhythm with distinct features at each stage. There is practical application to understanding ultradian rhythms, technology and devices based on understanding sleep stages have been developed. These track sleep and help individuals improve sleep. Avoiding waking in stage 4 stops people from feeling disoriented. This type of technology leads to a happier, healthier and more economically productive population. The menstrual cycle is affected by exogenous cues, when several women of childbearing age live together and do not take oral contraceptives, their menstrual cycles tend to
hour circadian pattern. This supports the importance of the SCN regulating the 24-hour circadian rhythm. Artificial light at night can disrupt the circadian rhythm, Touitou et al showed that teenagers spent increasing amount of time on electronic media at night. The LED bulbs are enriched with blue light. This leads to the suppression of melatonin secretion and circadian disruption. As a result, adolescent sleep becomes irregular, shortened and delayed. In the long-run, sleep deprivation can lead to increased rates of cardiovascular disorders and mood disorders such as depression. Burgess et al exposed volunteers to light treatment in order to shift their sleep-wake cycles. Participants sleep patterns and melatonin levels were monitored in a lab. Participants who were exposed to bright light felt sleepy two hours earlier in the evening and woke up two hours earlier in the morning. This shows that circadian rhythms can be shifted by light exposure, which could be useful for air travellers.
