the divisions of the nervous system the human nervous system body wide system of nerve cells that collects information from the world processes this information and then takes action by directing bodily organs and muscles via the transmission of electrochemical messages central nervous system
CNS involves complex processing includes the brain for all conscious and most unconscious processing and the spinal cord which receives and transmits information and some reflex processing
peripheral nervous system pns a body-wide network of messenger neurons sensory afro neurons take information to the CNS a motor aerate neurons take information away from the CNS autonomic nervous system ANS the part of the pns that controls actions of internal glands and is an involuntary system so not under conscious control
somatic nervous system SNS the part of the pns that controls skeletal muscles it's a voluntary system so underc conscious control
sympathetic system part of the ANS increases bodily activities release of neuro adrenaline activates in FAL flight response increases heart sweat breathing rate and dilates pupils
parasympathetic system part of the ANS decreases bodily activities releases acetylcholine activates and rest and digest decreases heart sweat and breathing rates constricts pupils usually homeostasis is maintained this means our internal environment is regulated by a balance between the sympathetic and parasympathetic systems
the endocrine system is a collection of glands around the body that regulate bodily functions growth and psychological factors it acts by releasing chemical Messengers called hormones into the blood examples of glands a hormone the gland producers and the effect of the hormone a
pituitary gland also known as the master gland hormone a controls the release of hormones from other glands B hypothalamus hormone crh links the nervous system to the endocrine system
C pineal gland hormone melatonin modulates sleep pattern keeping the body to a day night Rhythm D
thyroid gland hormone thyroxine modulates metabolism the rate of use in the body e Fus gland hormone fosin stimulates the development of tea cells in the immune system f
pancreas hormone insulin regulates blood sugar levels G
adrenal glands hormone adrenaline regulates the effect of the fight or flight response H
ovaries hormone estrogen develop secondary sexual characteristics in females I
testicles hormone testosterone leads to the development of secondary sexual characteristics in males
the structure function of sensory relay and motor neurons together they're termed the reflex arc cell one is a neuron its function is detect Sensations for example pain at sensory receptors an action potential then travels across the nerve passing along the melinated axon and then the electrical signal is converted into a chemical signal to cross the syapse
cell 2 is a relay neuron it's function is after SED transmission and new action potential forms in the dendrites this neuron is in the spine and sends a signal to the CNS but also immediately sends a signal along its axon to the motor neuron self fre
is the motor neuron its function is to detect the signal from the relay neuron by a synaptic transmission and then pass the signal along its own mated axon to stimulate an effector for example a muscle group in the arm moving it away from the source of pain the process of sign up to transmission the syapse alsoo called
an axon terminal this structure is found at the end of a nerve cell a neuron and allows neurons to communicate by passing on chemical signals this process is called synaptic transmission
neurotransmitters are the chemical messages released by neurons these are either excitatory so stimulate making more likely or
inhibitory making less likely the development of an action potential an electrical message in the other postoptic neuron the process the action potential travels down the axon of the prestic neuron this forces vesicles containing neurotransmitters to merge with the cell membrane and release neurotransmitter into the stic CFT receptors on the postseptic neurons dendr membrane detects the presence of neurotransmitters changing the chemistry within the post synaptic neuron if the charge inside the post synaptic neuron passes a threshold and new action potential forms and the message is passed on the neurotransmitters detach from The receptors and return to the preoptic cell via transport proteins this process is called reuptake excitation excitatory neurotransmitters increase the likelihood of a new action potential forming in the postoptic cell when detected by receptors the electrical charge inside becomes more positive and likely to fire this is depolarization inhibition inhibitory neurotransmitters decrease 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 hyperpolarization summation is the combined effect of all inhibitory and exit influences resulting in a new action potential forming or not unidirectional information can only be passed between the pre and post- synaptic neurons in One Direction this is due to the structure of the syapse such as the location of neurotransmitters in the presynaptic cell and receptors in the post synaptic cell fight or flight response the fight or flight response is an evolutionary survival mechanism in response to a threat it prems a body and mind for Extreme Action such as fighting for our life or escaping a fret the body returns to homeostasis after the Fret is passed in the fight or flight response a stressor is first detected by the hypothalamus HPA axis in the endocrine system is activated and the py gland releases a hormone HCT this is detected by the adrenal cortex releasing cortisol the hypothalamus also activates a sympathetic branch of the ANS and the adrenal medula is triggered via the sympathetic adrenal medular pathway releasing adrenaline role of adrenaline psychological effects of adrenaline include increased anxiety attention and alertness the physical effects of adrenaline include increased blood flow to the brain and skeletal muscles quick thinking and reactions and decrease blood flow to the skin and the digestive and immune systems Dilated Peoples improve vision and faster breathing weate increase oxygen the fal flight response is not designed for the modern world it's maladaptive in most situations it's frequently triggered by stimuli that cannot be run away from or four for example exams in the short term this results in acute stress a response to immediate pressures exciting in small amounts and giving you focus and energy but exhausting and maintained long-term frequent triggering of the fight or flight response results in chronic stress which can result in stress related illness affecting the immune and circulatory systems hey there I just still watching I'm guessing you'll find this video useful as I release content right up to the exams don't forget to subscribe so you know when new videos are uploaded all also as this video is being released I'm on around 50,000 subscribers and I'd love to get to 100K at some point in the next few years localization of function in the brain and hemispheric lateralization localization of function functions such as movement speech or language and memory are performed in distinct regions of the brain they are localized the opposite view is the brain acts holistically to perform functions contralateral each hemisphere of the brain right or left controls the opposite controlateral side of the body including both motor and sensory Pathways and vision of the contralateral visual field hemispheric lateralization each hemisphere of the brain right or left is specialized to perform different functions language centers are in the left hemisphere Visos spatial tasks are best performed by the right motor samata sentory Visual and auditory cortices are on both sides of the brain broer and Vern's area are only in the left hemisphere function of the motor cortex voluntary muscle motor movements across the body it's controlateral it's at the back of the frontal lobe and separated from the somat sensory cortex by a fold called the central sulcus damage injuring the Moto cortex results in the loss of muscle function or after severe trauma Paralysis on the opposite side of the body function of the somat centry cortex receives sense Impressions from around the body it's contralateral it's at the front of the pretal lobe and separated from the motor cortex by a fold called the central sulcus damage loss of sensation in the opposite side to the damage ignoring areas of the body called neglect syndrome function broas area located in the left frontal lobe only brochas area is responsible for speech produ uction damage results in motor phasia difficulty producing fluent speech function are ven's area located in the left frontal low only it's responsible for speech comprehension damage results in sensory as phasia difficulty understanding speech function of the udit cortex receives and processes sound information from ears located in both hemispheres function of the visual cortex occipital L visual processing in each hemisphere receives information from the opposite visual field clinical case study research demonstrates the loss of certain functions if damage is caused to particular areas of the brain for example brocker and Vern's case studies as phasia and Clive wearing Amnesia this suggests these functions like language and memory recollection are localized and located in the area's damage the use of case studies are seen as unscientific especially in Brain Research with damage often covering multiple regions as seen when modern MRI scans were made of tan brain modern brain scanning techniques like fmri supports older research on language centers showing activation in the regions previously Associated when healthy participants perform language tasks motor and semat sensory functions are highly localized however some systems are more distributed and some functions like Consciousness appear to not be localized at all this suggests the correct approach in arguing for the localized or holistic nature of the brain is dependent on the function also due to the high connectivity of the brain no one area is truly independent split brain research the brain is controlateral each hemisphere of the brain right and left controls the opposite controlateral side of the body the visual cortex processes the visual information from the the opposite visual field the two hemispheres do communicate they're connected by the Corpus glom a thick bundle of 200 to 300 million nerve fibers cutting the corpos clom was a surgical procedure for epilepsy isolating each hemisphere from the other the corpos colostomy reduced epileptic symptoms and has few side effects for such an invasive procedure however unusual behavior and a sense of a loss of agency a feeling of control LED to research sp's 1968 split brain research was a quasi experiment using 11 patients who had all undergone Corpus colostomy very projected information to each visual field so controlling the information that each hemisphere had access to in a series of tests participants would be required to say either what they had seen draw the object or select from a number of objects that were hidden from view with their hands findings information presented to the left hemisphere could be spoken but not spoken if delimited the right hemisphere however the right hemisphere could draw or select the object by using left hand suggesting the hemispheres are both capable of acting independently memories and awareness also reporting the theory that language centers are in the left side of the brain Ginger's 1983 split brain research also used patients who had undergone Corpus colostomy found that when each hemisphere of the split brain patients were presented with faces the right hemisphere was much more able to recognize them suggesting the right hemisphere is specialized for facial recognition the sample of split brain patients in these studies is small also participants were compared against non-tics had varying amounts of connection cut and all undergone drug therapy the control group used by Spar were healthy with no history of fits this suggests that some of the results may be endued to participant variables making the results ungeneralizable to the Wi population the experimental procedure used in split brain patients is also unlike how these individuals would process information and act in normal day-to-day life the tasks lact mundane realism in reality these people led mostly normal lives moving their head from side to side and using other cues to pass on information to both hemispheres resulting in low external validity research on split brain patients has had a fundamental impact on the psychological and philosophical understanding of both the Unity of Consciousness and identity suggesting that the brain is a combination of separate intelligent processes working together plasticity and functional recovery plasticity the brain adapts in both its function and structure as a result of a change in the environment these changes could be due to damage or to meet the cognitive demands of learning new skills four reasons for plasticity are learning new skills a result of Developmental change response to direct trauma to areas of the brain response to indirect effects of damage such as brain swelling or bleeding from stroke functional recovery the functions that were performed by areas of the brain that are now lost neuronal cell death or damaged are performed by undamaged areas of the brain functional reorganization synaptic pruning synapses that are used frequently become stronger Over time however unused synaptic connections are lost this makes the brain a more efficient communication system over time axonal sprouting is when existing neurons grow new axons to connect to adjacent neurons neural generation is the growth of new neuronal cells then inovation super sensitivity to compensate for the loss of axons in a pathway the remaining axons become more sensitive more likely to fire this can result in side effects such as pain factors affecting recovery age children have the best ability to recover then young adults gender women are more able to recover from brain damage access to rehabilitative therapy focused effort results in Improvement constraint juice therapy is stopping patients from using coping strategies for example using undamaged limbs for tasks Maguire 2000 and M of 16 male taxi drivers compared to an MRI of 16 matched age gender non- Taxi Driver controls the posterior hippoc campi of the London taxi drivers was found to be significantly larger than controls suggesting the physical structure of the brain is plastic able to reconfigure itself to better adapt to psychological demands Danielle E's case study a 14-year-old EB at two EB had a hemispherectomy of the left side of his brain to remove a tumor this removed The Language Center of brochas and Veri area immediately after surgery EB had lost all language ability as phasia however after two years of recovery EB had recovered his language ability research on brain plasticity and functional recovery has practical benefits it's been useful in reuil to therapy use for example can straighten use therapy stoping patients using copon strategies like body language for communication or undamaged lmbs tasks this makes improve vof functional reorganization helping people return to their lives and productive work ultimately benefiting The Wider economy research in individuals recovering loss function can help psychologists understand more about the functions of the regions of the brain that were initially damaged my fire to 2015 a Metro analysis demonstrated that not everyone has high levels of plasticity finding IQ and educational background are positively correlated with better outcomes after traumatic brain injury suggesting some individuals have a greater cognitive Reserve helping in recovery and some people will struggle to regain function ways of studying the brain functional magnetic resonance imaging fmri fmri detects blood flow in the brain as more active areas of the brain need more blood containing oxygenated hemoglobin with distinct magnetic properties these active areas can be compared a low activation areas of a lower blood supply and displayed on an fmri image fmri has good spatial resolution of approximately 1 mm precisely identifying active brain regions and patterns of activation over time are participants complete experimental conditions fmri is noninvasive and it's safe techniques for experiments compared to options that use radiation like pet scanners poor temporal resolution as one image is taken every few seconds and delay in blood flow after activity many brain processes are too fast to study fmri machines are expensive to build and operate also as the patient needs to be still experiments with body movement are not possible Electro andram eegs the EEG device is a cleation between 22 and 34 electrodes are attached to a cap and then fited carefully to the scalp with conductive gel the readal from each electrode is the sum total of activation of the brain cortex under the electrode this is displayed as a series of lines showing distinct patterns called brain waves amplitude the size of the Waves show Brain Wave intensity the frequency the distance between each wave shows the speed of activation each G has been historically important in understanding brain activity in areas such as sleep research and medical diagnosis it's cheaper than Alternatives such as fmri and is able to be used in experiments in which the participants move very good temporal accuracy measuring brain activation with a resolution measured in millisecs or spatial activity as the passin is the sum of a large number of neurons in the cortex under the electrode also cannot detect activity deep within the brain event related potentials erps event related potentials use the same technique and Equipment as EEG what presents a stimulus many times creating a smooth curve of activation by combining the data in a process called statistical averaging this removes background noise unrelated to stimulus the waveforms Peaks and dips show exactly when cogntive processes in the brain happen after the stimulus is presented erps allow researchers to isolate and study how individual cognitive processes take place in the brain while eegs record General brain activity like eegs erps have good temper resolution within a millisecond sampling rate but very poor spatial resolution some processes cannot be studied by Erp as they cannot be presented a large number of times with the same response postmortem examinations brains are precisely cut after a treatment to give them a Firma texture when usual brains are detected such as brains that have suffered trauma or from individuals with mental illnesses these brains are compared to neurotypical healthy brains rocker area responsible for language production was discovered using a postmortem on a patient called tan who could only say tan expressive as phasia damage in an area of the frontal lobe was found after Tan's death the high space IAL resolution of postmortem allows the study of microscopic brain structures down to the neuronal level as postmortem is not carried out in the living brain unusual behavior in life and damage found is correlational however theories are then generalized that can be tested with other experimental technique circadian rhythm a cadium rhythm is a biological Rhythm that lasts around 24 hours we have a cadium rhythm for regulating sleep and wake the release of hormones and varying our body temperature and blood pressure endogenous pacemakers EP are in internal body clocks that keep biological processes to time exogenous zabers e said are external cues that entrain internal body clocks altering EPS to match the environment the sleep wake cycle is the pattern of sleep and wakefulness that repeats every 24 hours like light and social cues in situations like jet lag the EP will be entrained by the ezs to the new time zone but it can take several days the super cmic nucleus fcn is the EP for the sleep wake cycle known as a Master Clock the scn is part of the hypothalamus within the lyic system it's located in the optic Chasm the point in the optic nerves where they cross when light is detected by the scn it sends a signal to the pineal gland stopping the production of melatonin a hormone that results in a sleep response light is thought to be the primary e in the sleep wake cycle but there are others for example social cues like when we time our meals or exercise when others go to bed or environmental cues like clocks see for in a cave for 179 days 6 months the cave had no natural light or other potential ex strenuous variables like clocks or social cues se's body clock EP maintained a regular cycle of around 25 hours without ease longer than the expected 24-hour cycle suggesting the EP for the Sleep Wiig cycle is free running but needs entrainment to keep to the 24-hour day night cycle psychologist have criticized the use of artificial lights in isolation experiments on the sleep wake cycle suggesting the artificial LS disrupted the Freer running Cadian River measurements by acting as an easy other studies that controlled for artificial light found the cadium Rhythm was closer to 24 hours with little drift Veta found 27 office workers who were exposed to strong blue light shifted the timing of The cadium rhythms to match the office lighting this suggests artificial light is a strong EZ for the sleep wake cycle Ralph surgically transplanted the scn between ordinary hamsters 24-hour cadium rhythm with ham with a town mutation 20 hour cadium Rhythm found the hamsters sleep wake cadium Rhythm shifted to match their new SN suggesting the scn is the EP in the sleep wake cycle Cadian Riven research has practical applications from understanding how blue light from devices disrupt sleep how to combat the adverse effects of jet lag and shift work and understanding the Cadian blood pressure Rhythm helps with timing drug treatments biological rhythms infradian an infradian Rhythm is a biological Rhythm that takes longer than 24 hours to complete one cycle one example is Seasonal effective disorder sad this is when an emotional mood lowers in the winter and improves in the summer and it's suspected this is due to the lack of sunlight in the winter the menstrual cycle is a 28-day cycle in fragum rhythm with 6 days of fertility however Cycles can be shorter or longer ranging from between 24 and 35 days biological aspects of the cycle include releasing the egg ovulation thickening of the womb lining and losing the wom lining during menstruation these biological changes are regulated by the hormones estrogen pre-ovulation and progesterone postovulation the levels of these hormones act as endogenous pacemakers keeping the biological processes to time acting as an internal body clock for the menstrual cycle it's thought that the pheromones of other women can act as exogenous zabers resulting in women who live together synchronizing their Cycles mlenuk found 135 women who lived in the same dormatory at University appeared to synchronizer Cycles with their friendship groups this suggests the menual cycle and fraan Rhythm synchronizes Stern and mlin 20 women were given pants taken from the armpits of donor women to wipe them their top lip every day it was found that the women would either shorten or extend their menstrual cycle to match the donor this suggests infradian Rhythm synchronization is due to the presence of pheromones acting as these Zs while the use of pheromones as a chemical messaging system is common in animals it's not widely accepted among scientists that humans have the ability to detect these signals Trevor found cohabiting lesbian couples did not synchronize the optimal conditions for possible synchronization countering muk's varies as menstrual cycles can vary in length women can appear to synchronize just due to their variability in their Cycles some not taken into consideration in all of the studies showing positive results evolutionary theories conflict some argue synchronization is advantageous stopping one male impregnating all women at once leading to genetic diversity in small human groups or Mal adaptive if they synchronize not all women could be fertilized by the male with the best genes needing to compete with other women for it biological rhythms ultradian an ultradian Rhythm is a biological Rhythm that takes less than 24 hours to complete one cycle the stages of sleep is one example there are four sleep stages stages 1 to three and nonr sleep or NR termed N1 N2 and N3 after passing back through N2 and N1 stage four is rem or rapid eye movement sleep most streams occur in r one cycle takes about 90 minutes and repeats four to five times over the course of a night's sleep each cycle tends to include a larger proportion of REM sleep and a shorter duration of M3 the stages of sleep are identified by measuring distinctive brain wave patterns using an EEG Delta feta Alpha Beta gamma these waves vary by frequency how close the waves are to each other measured in Waves per second or Hertz and amplitude the size of the brain wave voltage the feta and Delta brain waves distinguish sleep stage ages sleep stages N1 falling asleep sensation easy to wake and there may be sudden body movements hypnic jerks a sensation of falling and hypnogogic hallucinations N2 hardest awake the body's relaxed heart rate and body temperature are lowered and the eyes are still and free is the deeper sleep very difficult to wake the body is most relaxed with heart rate at is lowest sleep becomes deeper from N1 to N3 you're less easily woken there's a slowing of brain wave frequency and increased amplitude REM is similar to wakefulness as seen on EEG however the body is paralyzed characterized by rapid movement and associated with dreaming when woken people report vivid dreams in this stage the brain returns to N1 after Ram Derma and kman used EEG to record the brain activity of 33 participants during one night's sleep brain waves followed a cyclic activation pattern with bodily relaxation during slow W sleep and rapid eye movement during periods of high activation this support the theory that stages asleep are an ultradian rhythm with distinct features at each stage Shapero ultra marathon runners showed longer sleep after intense physical activity also an increased proportion of slow wave sleep and free supports the theory that slow wave sleep is for the body's physical recovery Hider EG's patients recovering from drug overdose showed increased RM sleep suggesting RM is for mental recovery the overall pattern of sleep stages is consistent however there are individual differences with newborn babies spending 80% of sleep in RM compared to 20 to 25% in adults this suggests the stages of sleep is not a simple process but adapts to the developmental needs of the individual cesler found that the longest period of REM sleep coincides with the lowest point on the Cadian body temperature cycle this suggests that the Cadian ultradian rhythms are connected and perhaps shouldn't be considered separate processes both processes could use the same internal body clock EP the super chasmic nucleus scn there are practical applications 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 four stops people from feeling disoriented this type of Technology leads to a happier healthier and more economically productive population if you want to try out the app all the topics and paper one are free and you can get on iOS or Android if you want to see model answers to bioy ol questions or access my other resources there's also patreon speaking of patreon I do want to thank all of my patrons for their support with the help of all of these students and teachers I'm able to teach part-time so I can work on the main mission of site boost the development of a free to watch and hopefully high quality a level psychology course and a special thank you to cat posnik and ammed Romani for supporting at the developer level so thanks to them good luck with your revision and I'll see you in the next p video