Morning Flashcards
nervous and endocrine system
-specialise network of cells in human body-primary internal communications system-based on electrical and chemical signals. 2 functions collect process and respond to information in environment and to coordinate the working of different organs and cells in the body. central peripheral. central brain and spinal chord. brain is centre of all conscious awareness and outer layer cerebral cortex’s 3mm thick only in mammals. Brain highly developed in humans-what distinguishes our higher mental functions from those of other. spinal cord passes to and from brain and connects nerves to PNS, also reflex actions.PNS transmits messages via neurones to and from central
-PNS subdivided into autonomic(governs vital functions in body eg breathing heart rate sexual arousal, somatic governs muscle movement and receives information from sensory receptors.
-endocrine system works alongside nervous to control vital functions in body-more slow, but widespread and powerful effects. gland produce hormone secreted into blood.thyroid gland thyroxine-affects cells in heart increases heart rate and cells throughout body increasing metabolic rate.pituitary gland master gland -controls the releases of hormones from all other endocrine glands in body.
-fight or flight-work in parallel.stressor perceived,hypothalamus activates pituitary gland which triggers activity in sympathetic branch of ANS. ANS changes from parasympathetic resting state to sympathetic physiologically aroused state.
-stress hormone adrenaline released from adrenal medulla(part of adrenal gland lying near kidney) adrenaline triggers physiological changes in body eg increased heart rate which creates psychological arousal necessary for fight or flight.
-All happens instant threat detected -this is acute response and automatic response.
-parasypathetic NS returns body to its resting state-this branch works in opposition to sympathetic NS-its actions are antagonistic to sympathetic system-reduces activities of body that were increased by actions of sympathetic branch.-rest and digest response.
-sympathetic state-increase heart,breathing rate, dilates pupils, inhibits digestion, inhibits saliva production, contracts rectum.
neurones and synaptic transmission
-100 billion neurones (nerve cells) in humans NS. 80% in brain-provide NS with primary means of communication. Sensory neurone-carry messages from PNS to CNS-long dendrites short axons. relay neurones connect sensory to motor or other relay neurones-short dendrites and axons. Motor neurones-connect CNS to effectors eg muscles/glands, short dendrite Long axons.
-neuron-cell body includes nucleus-contains genetic material of cell.dendrites protrude from cell body, carry nerve impulses from neighbouring neuron to cell body.Axon away-covered in fatty layer of myelin sheath-protects axon and speeds up electrical transmission of impulse-myelin sheath segmented by gaps nodes of ranvier-speed up transmission of impulse-force impulse to jump across gap along axon. At end of axon are terminal buttons which communicate with next neuron in chain across synapse.
-cell bodies motor neurones in CNS but long axons form part of PNS. Sensory neurones located outside CNS in PNS on clusters ‘ganglia’. Relay neurones 97% of all neurones most found within brain and visual system.
-when neuron activated by stimulus inside of cell becomes positively charged for split second causing action potential to occur-creates electrical impulse that travels down axon towards end of neuron.
-acetylcholine is found at each point where motor neuron meets muscle-upon release cause muscle to contract.
-neurotransmitters have excitatory or inhibitory effect on neighbouring neuron eg serotonin-inhibition in receiving neurone-becoming more negatively charged.adrenaline (hormone and neurotransmitter) excitation-increasing positive charge.
-summation-whether post synaptic neuron fires-excitatory and inhibitory influences summed-if net effect on post synaptic neuron in inhibitory then less likely to fire. Action potential of the postsynaptic neuron is only triggered if sum of excitatory and inhibitory signals at any one time reaches threshold.
localisation of function in the brain
-19th century-scientists eg Paul Broca and Carl Wernicke discovered specific areas of brain associated with particular physical and psychological functions
-localisation of function-the idea that different parts of the brain are responsible for specific behaviours, processes or activities.
-main part of brain cerebrum, cerebral cortex thin outer layer-of both hemispheres-cortex subdivided into four centres-called lobes-a lobe is part of an organ that is separate in some way from the rest.
-back of frontal lobe=motor area-controls voluntary movement in opposite side of body-damage may result in loss of control over fine movements.
-at front of both parietal lobes is somatosensory area-separated from motor area by ‘valley’ called central sulcus-somatosensory area is where info from skin is represented, amount of somatosensory area devoted to particular body part denotes its sensitivity eg face and hands over half.
-occipital lobe-back of brain-visual area (or visual cortex). each eye sends info from right VF to left VC. So damage to left hemisphere produce blindness in part of right visual field in both eyes.
-temporal lobes-auditory area-analyses speech based information (damage-hearing loss), damage to specific area wernickes affect ability to comprehend language
-language-left side of brain-Broca-identified small area in left frontal lobe responsible for speech production.damage-speech aphasia-slow laborious and lacking fluency.Broca patient Tan-people with Broca aphasia difficulty with prepositions (show relationship between noun and sentence eg in under into) and conjunctions (the, and)
-wernicke described people no problem producing language couldn’t understand it such that the speech they produced was fluent but meaningless. wernickes area in left temporal lobe-responsible for language understanding-wernickes aphasia when damaged-produce nonsense words
as part of the content of their speech.
-s-evidence from neurosurgery-eg cingulotomy-isolate region cingulate gyru-implicated in OCD.44 ppl after 32 weeks 30% met criteria for successful response to surgery,14% for partial response
–s-evidence brain scans-wernicke area active listening task and brocas reading, review of LTM studies show semantic and episodic memories reside different parts of prefrontal cortex. C-removed areas of cortex in brain between 10% and 50% in rats that were learning to route through maze. no area more important than another in ability to learn route -learning require every part of cortex
-L-2% modern researchers think language in brain completely controlled by brocas and wernickes areas-fmri-language streams-including brain regions in right hemisphere as well as subcortical regions eg thalamus.
hemispheric lateralisation
language is lateralised-wernicke and Broca area in left temporal and frontal lobe . RH only produce rudimentary words(basic like simple expressions often emotionally charged like oh my god) and phrases-contributes emotional context to what is being said (eg pitch). LH analyser and RH synthesiser.
-motor area cross wired (contralateral wiring)-RH controls movement on left side of body.
-vision-contralateral and ipsilateral(opposite and same sided) eg left visual field of both eyes connected to RH-enables visual areas to compare the slightly different perspectives from each eye and aids in depth perception.
-similar arrangement for auditory input to auditory area and differences from two inputs helps us locate source of sound.
-split brain operation involves severing corpus callosum-used to reduce epilepsy.showing image to one hemisphere from one visual field meant info couldn’t be conveyed from that hemisphere to another.
-when picture of object shown to RFV connected to LH the ppt could describe what was seen -couldnt do this if shown to LFV-because messages from RH normally relayed to language centres in LH. left hand able to select a matching object out of sight using left hand linked to RH, also able to select an object most closely associated eg ashtray and cigarettes. If pinup picture shown to LFV there was emotional reaction giggle but ppts reported seeing nothing. LH verbal RH silent but emotional.
-s-hemispheric lateralisation-pet scans-which areas active during visual processing task.ppts with connected brains asked to attend to global elements of image eg forest regions of RH more active, finer details eg individual trees the specific areas of the LH tended to dominate.-thus hemispheric lateralisation feature of connected brain as well as split brain.
-L-hemispheric lateralisation-LH analyser and RH synthesiser wrong-research suggests people don’t have dominant side of brain which creates different personality. analysed brain scans over 1000 people aged 7-29 d found people used certain hemispheres for certain tasks-no evidence of dominant side eg mathematicians/artists brain, notion of right or left brained people wrong
-s-sperry-research split brain ppts perform better on certain tasks-eg identifying odd one out in array of similar objects-LH better cognitive strategies are watered down by inferior RH
Plasticity and functional recovery of brain after trauma
-brain appear to be plastic as has ability to change throughout life-during infancy brain experiences rapid growth in number of synaptic connections it has- peaking 15000 per neuron at 2-3 years-2x many as adult-as we age rarely used connections are deleted and frequently used connections strengthened=synaptic pruning-enables lifelong plasticity where new neural connections are formed in response to new demands of brain.
-Maguire-studied brains of London taxi drivers-found significantly more grey matter in posterior hippocampus than matched control group-associated with development of spatial and navigational skills.As part of training London cabbies must take ‘the knowledge’-this learning alters structure of brain-longer been in job more pronounced the structural difference.-medical students Draganski imaged 3 months before and after final exams-changes to posterior hippocampus and parietal cortex.
-functional recovery-after physical injury or stroke-unaffected areas able to adapt and compensate for damaged-functional recovery that may occur example of neural plasticity.-process occur quickly after trauma then slow down after couple of weeks or months, rehabilitative therapy
-brain rewire and reorganise itself by forming new synaptic connections close to area of damage. secondary neural pathways not typically used to carry out certain functions activated/unmasked. these processes supported by number of structural changes in brain-axonal sprouting (growth of new nerve endings (branches) grow from existing healthy neurones which connect to other undamaged nerve cells to form new neuronal pathways),denervation super sensitivity,recruitment of homologous areas on opposite side of brain.
l-plasticity-prolonged drug use dementia,60-80% amputees phantom limb syndrome-cortical reorganisation in somatosensory cortex that occurs due to limb loss.
s-plasticity lifelong-40h golf training produced changes in the neural representation of movement in ppts aged 40-60.fmri increased motor cortex activity in novice golfers compared to control-suggest more efficient neural representations after training.
-s-functional recovery-neural rehabilitation-constraint induced movement therapy-stroke patients
-l-education-cognitive reserve-40% of those who experience DFR had more than 16 years education-10% of less than 12 years.
ways of studying the brain
-fMRI-functional magnetic resonance imaging-detect changes in both blood oxygenation and flow that occur as neural activity in specific parts of brain. 3D image (activation maps)
-EEG-electroencephalogram-measures electrical activity-electrodes-fixed to scalp using skull cap-recording represents brainwave patterns generated from action of thousands of neurons-provides overall account of brain activity-diagnostic tool arrhythmic patterns
-ERP-eeg data has all neural responses to specific sensory, cognitive and motor events. through statistical averaging technique-extraneous brain activity filtered out -brainwave triggered by particular event or stimulus-also cognitive processes eg attention.
-post mortem-usually rare disorder and have experienced unusual deficits in cognitive processes or behaviour during lifetime.-comparison.
-fmris-no radiation-high spatial resolution. -poor temporal resolution 5 second time lag
-eeg-sleep cycle,diagnosis epilepsy,high temporal resolution-single millisecond -generalised nature of info received, cant pinpoint exact source of neural activity therefore cant distinguish between activities originating in different but adjacent locations.
-erp-temporal,-measure cognitive functions and deficits eg allocation of attentional resources and maintenance of working memory. -lack of standardisation in methodology between different research studies-makes it difficult to confirm findings-background noise completely eliminated which is hard.
-PMs-foundation for early understanding of key processes eg Broca and wernicke, HM identify brain damage which linked with memory deficits. -causation however and ethical issue informed consent eg HM no memories
circadian rhythms
-biological rhythms exert important influence on way body systems behave . all rhythms governed by endogenous pacemakers. (internal biological clock) and exogenous zeitgebers (changes in environment)
-circadian-rhythms that last around 24 hours.
-sleep/wake cycle-governed by endogenous pacemaker suprachiasmatic nucleus (SCN)-lies just above optic chasm which provides information from eye about light.exogenous zeitgebers reset SCN
-Siffres cave study test free running biological rhythms-resurfaced in mid-september 1962 after 2 months in caves of southern alps believing it to be mid august-later similar but 6 months in texan cave-each case free running settled down just beyond 24 hours-25
-similar results-Aschoff and Wever-convinced group spend 4 weeks in WW2 bunker (all but one-who extended to 29 hours) displayed circadian rhythm 24-25 hrs. both studies suggest natural sleep wake cycle slightly longer 24 but entrained by exogenous associated with 24 hr day eg daylight meals.
-shouldnt overestimate exogenous-Folkard et al-studied group of 12 who agreed to live in dark cave 3 weeks, bed 11;45 rising 7;45-researchers gradually sped clock up24-22 hr day, only one ppt able to comfortably adjust to new regime-suggest strong free running circadian
-s-shift work-reduced conc 6 morning(circadian trough),shift workers 3x more likely develop heart disease. C-correlation, other factors eg divorce in shift workers due to strain of deprived sleep and missing out on family events.-so not biological factors.
-s-improve medical treatments-circadian coordinate number of bodies basic processes eg heart rate digestion-rise and fall during day-led to field of chronotherapeutics-how medical treatment can be administered in way that responds to biological rhythms. eg aspirin for heart attacks last thing at night-as more likely in morning-aspirin reduces platelet activity in blood
-L-individual differences generalisations difficult to make-small samples-research found individual differences in sleep wake cycles varying from 13 to 65 hours. another study showed natural preference for early bed (larks) or owls. siffre observed own sleep wake cycle slow down
Infradian and ultradian rhythms
-infradian-menstrual cycle-regular ovulation-cycle between time womb lining shed to day before next period . 28 days approx -24-35 considered normal, rising oestrogen cause ovary to develop egg and release (ovulation).After ovulation progesterone helps womb lining grow thicker, readying womb for pregnancy, if no pregnancy egg absorbed and lining shed.
-endogenous system which may be influenced by exogenous factors. Stern and McClintock-29 women with history of irregular periods, samples of pheromones gathered from 9 at different stages-cotton pad under armpit-8 hours-treated with alcohol and frozen-rubbed on upper lip of other ppts. Day one given pads from start of cycle day two given pads from day 2 etc. 68% experienced change to cycle bringing them closer to donor.
-SAD-often referred to as winter blues-during winter months when daylight shorter. Specific type of infradian-circannual rhythm, yearly cycle, can be classed as circadian as SAD may be due to disruption of sleep wake cycle -melatonin implicated in cause of sad, pineal gland secrete, lack of light in. morning mean secreted for longer-knock on effect to production of serotonin.
-ultradian rhythms-sleep cycle-5 stages 90 mins -each stage different brainwave activity measured with EEG.
-1 and 2-light sleep where person may be easily woken-stage 1 brain waves high frequency short amplitude-alpha waves-stage 2 alpha waves continue but occasional random changes in pattern called sleep spindles.
-3 and 4–delta waves with low frequency and high amplitude-difficult to wake someone at this point,
-5-REM sleep-body paralysed yet brain activity resembles awake brain-brain produces theta waves -eyes occasionally move around(REM)-dreams most often but can occur in deep.
-L-significant variation between people-Tucker et al found large differences between participants in terms of the duration of each sleep stage, particularly 3 and 4-suggested differences likely biological determined.
endogenous pacemakers and exogenous Zeitgebers
-suprachiasmatic nucleus-tiny bundle of nerves located in hypothalamus in each hemisphere of brain, one of primary endogenous pacemakers.nerve fibres connected to eye cross-optic chiasm-suprachiasmatic nucleus just above gets info from optic.occurs even when eyes closed-bio clock adjusts even when sleeping
-DeCoursey destroyed SCN connections in 30 chipmunks and observed for 80 days, sleep wake cycle disappeared and significant proportion had been killed by predators because were active when they should have been asleep
-ralph et al bred mutant hamsters with 20 hr sleep wake cycle-transplanted SCN cells from foetal tissue from mutant into brain of normal hamsters-cycles of second group defaulted to 20 hours.
-scn passes daylight info to pineal gland -increased production of melatonin-induces sleep -also causal factor of SAD.
EZ-external factors that reset our biological clock through entrainment, free running biological clock ticks in a distinct cyclical pattern-brought into line by EZ
-light also has indirect influence on processes that control functions eg hormone secretion.
-campbell and murphy- 15 ppts woken at various times and light pad shone on back of knees-sleep wake pattern deviated by 3 hours in some cases.-light is powerful EZ that need not rely on eyes to exert influence on brain.
-social cues-babies sleep wake cycle random-6 weeks circadian rhythm begin-babies rhythms entrained by schedule by parents-jet lag research shows adapting to local times for eating and sleeping is good way of entraining circadian rhythms.
-L-SCN research may obscure other body clocks-numerous circadian rhythms in many organs and cels-peripheral oscillators found in organs including lungs influenced by SCN but also independent.changing feeding patterns in mice cld alter ultradian in liver cells 12 hours while leaving SCN rhythm unaffected.
-l-recount study of young man blind by birth who had abnormal circadian rhythm 24.9 hrs, sleep wake cycle couldn’t be adjusted despite social cues
