40104649
Description
Flashcards by Darcey Griffiths, updated 9 months ago
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Created by Darcey Griffiths
10 months ago
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| Question | Answer |
| The brain | Adult brain weighs 1.4kg- estimated 9.8x10^10 neurones- no neurones per mg brain tissue= 9.8x10^10/1.4x10^6= 7.0x10^4 (1dp)- high connectivity is needed for generating properties of the brain- also many glial cells- supports neurone functioning- evolutionary development of brain can be investigated- comparing to brains of other vertebrates- those earlier in fossil record= simpler brains- correlated w/ their range of behaviours |
| Before starting | for the love of god please look at diagrams along with this please |
| Meninges | Spinal cord surrounded w/3 membranes or meninges - delicate pia matter on brain surface - thick dura matter attached to skull - arachnoid matter between Inflammation of meninges= meningitis- viral meningitis- more common/ mild compared to bacterial meningitis- can be fatal |
| Ventricles | Ventricles= 4 connected cavities in the brain into which cerebro-spinal fluid is secreted- right lateral, left lateral,3rd/4th ventricle- diagramn-309- CB fluid: -supplies nutrients eg glucose/ oxygen carried in solution- doesn't have red blood cells- looks yellow - has antibodies/ white blood cells- has role in resisting infection all factors- similar to plasma |
| Regions in the brain- hindbrain | 3 regions- forbrain, midbrain, hindbrain- evolution modifies what's already present- later species have more sophisticated but not necessarily new structures- hindbrain includes the medulla oblongata and cerebellum; • medulla oblongata - involved with the control of heart rate, ventilation and blood pressure and contains many important centres of the autonomic nervous system; • cerebellum - involved with the maintenance of posture and the co-ordination of voluntary muscular activity e.g. writing; |
| Brain regions p2 | midbrain contains nerve fibres that link the forebrain to the hindbrain; • forebrain is made up of the hypothalamus, thalamus and cerebrum; -The thalamus= relay centre- sends and receives impulses from cerebrum • cerebrum controls the body’s voluntary behaviour, learning, reasoning, personality and memory; • hypothalamus - is involved in regulating body temperature, blood solute concentration, thirst, hunger and sleep. It is the main controlling region of the autonomic nervous system and provides a link between the brain and the endocrine systems via the pituitary gland. |
| Definitions | Cerebellum- Part of the hindbrain that co-ordinates the precision and timing in muscular activity, contributing to equilibrium and posture and to learning motor skills Medulla oblongata-Part of the hindbrain that connects the brain to the spinal cord and controls involuntary autonomic functions Cerebrum-2 hemispheres responsible for integrating sensory functions and initiating voluntary motor functions- It is the source of intellectual function in humans where it is more developed than in other animals |
| More on brain regions | hypothalamus and thalamus interconnect with different areas of the brain, including the hippocampus, to form the limbic system, which is involved in emotion, learning and memory; • hippocampus interacts with other areas of the cortex. It is involved in learning, reasoning and personality and also consolidates memories into a permanent store |
| Autonomic nervous system NOTE- A mammal is rarely fully relaxed or fully active and the two divisions work antagonistically - opposing signals from the two types of neurones adjust an organ's activity to an appropriate level. As exemplified by the control of heart rate | Part of the peripheral nervous system- controls automatic functions of the body by the antagonistic activity of the sympathetic and parasympathetic nervous systems Sympathetic ns-generally has excitatory effects on the body uses neurotransmitter noradrenalin- its impulses increase heart rate, blood pressure and ventilation rate- cell bodies= in grey matter/ ganglions outside spinal cord parasympathetic ns- uses acetylcholine- generally has inhibitory effect- decreases heart rate, blood pressure and ventillation- neurones= in brain, spinal chord/ also close to target organs |
| ANS and heart rate | Responses are under autonomic control by cardiovascular centre in medula oblongata During exercise cardio acceleratory centre= stimulated, impulses travel along sympathetic nerve fibres to sino atrial node- noradrenalin= released- binds to cell membrane receptors on SAN cells- SAN's electrical discharge increases in frequency- heart rate increases During sleep- cardio inhibitory centre= stimulated - impulses travel along p-sympathetic nerve fibres to SAN- acetylcholine= released-binds to membrane cell receptor cells- SAN's electrical discharge decreases in frequency- heart rate decreases |
| Cerebral cortex | brain is largely bilaterally symmetrical- cerebrum consists of two hemispheres which are connected to each other by a bundle of nerves known as the corpus callosum;- largest white matter structure in brain- structure of corpus callosum may explain why some areas of brain= lateralised - function a bit differently between hemispheres |
| More cerebral cortex | Outer 2-3 mm of brain= cerebral cortex- the cortex forms the outer layer (2-3mm deep) and its surface is highly folded to increase the amount of cortical area available for processing information; • it contains thousands of millions of neurones each with many synaptic connections and is responsible for most conscious thoughts and actions; • the cortex is composed of grey matter and contains many cell bodies, the inner area of the cerebrum is composed of white matter and contains myelinated axons-axons= deeper in brain than its cell bodies-myelinated but cell bodies aren't- unlike spinal cord in cerebrum- grey matter= surrounds white matter reptiles and fish-cc= small and simple- in mammals- cc has expanded greatly in size and complexity- is also called neocortex- high connectivity- responsible for cerebrum executing higher cog functions eg language, conscious actions thought and processing sensory input |
| Lobes of cerebral hemispheres | each cerebral hemisphere can be subdivided into four structural regions: parietal lobe and occipital lobe; Frontal- aspects of personality, site of reasoning/ planning/ emotions/ problem solving, dominant hemisphere has Brocas area- controls motor function of speech, contains motor cortex Temporal- includes auditory- generates sense of sound, processes complex stimuli, helps learning/memory, left temporal has Wernicke's area- associated w/ wriiten and spoken speech- lobe= not lateralised- neither is dominant Parietal- sense of taste- helps visual-spatial processing, includes somatosensory cortex Occipital- contains the primary visual cortex- associated w/vision |
| areas of cerebral hemispheres | Sensory areas (also called sensory/ somatosensory cortex)- receives nervous impulses from sense receptors of body via thalamus- nerve fibres from both sides of the body cross over in corpus collosum- so sensory area in cortex of one hemisphere processes info form sense receptors of other side of body Motor areas (motor cortex)- sends nervous impulses through corpus callosum to effectors on other side of body |
| areas of cerebral hemispheres p2 | motor areas send nerve impulses to appropriate effectors via motor neurones; • motor neurones, from the motor area, of one cerebral hemisphere cross over in the medulla oblongata and innervate the effectors on the opposite side of the body; • association areas make up most of the cerebral cortex and receive impulses from sensory areas and associate this information with previously stored information (from memory) which allows the information to be interpreted and given meaning; • the association area is also responsible for initiating appropriate responses which are passed to the relevant motor areas -Interpret,process and store visual info in visual association area Interpret, process and store auditory info in auditory association area |
| Stroke | Interruption of blood flow in the brain- cerebral artery fails to deliver oxygen to neurones of the brain - die-2 main causes ischaemic stroke- blood vessel is blocked - can be caused by a blood clot or thrombus forming at the site or an embolus eg blood clots, cholesterol, fat or bubbles of air travelling in blood stream- can be treated w/ clot busting medication in first 4hrs haemorrhagic strokes- bleeding into the brain or space around it- can cause intense headache- when brain cells die- impulses can no longer travel along fibres from brain's motor areas to effectors- causing paralysis- may be on 1 side of body |
| stroke P2 | on side of paralysis- muscle tone= lost- no muscle fibres are stimulated- face may droop- at corpus callosum-nerve fibres cross so stroke in one hemisphere affects body on opposite side can be increased w/ high blood pressure, tobacco smoking, obesity and high blood cholesterol- risk increases w/ age- strokes are diagnosed w/ physical exam and imaging but blood test and ECG can rule out other causes |
| Cortical homunculi | Homunculus- Drawing of the relationship between the complexity of innervation of different parts of the body and the areas and positions in the cerebral cortex that represent them- cortical homunculi - which parts of the body are related to the cerebral cortex sensory homunculus- shows relative sensitivity of different parts of the body- most sensitive areas are shown with largest area in drawing motor homunculus- different parts of the body represented by the motor cortex- very similar structure to sensory |
| Language and speech | Vocal animals have only 1 cerebral hemisphere to control language and speech- humans-usually left- use of 1 hemisphere= lateralisation Current understanding of the location for language control- sensory areas are in visual and auditory areas, association area is the Wernicke's area, motor area is the Broca's area |
| Wernicke/ Broca's area | Wernicke's area- association area- interprets written/ spoken language- damage can cause Wernicke's aphasia- patients do not understand the speech of other people- speak fluently and grammatically but their sentences often use words that're unrelated- word salad |
| Broca's | Broca's- 1st language area discovered- it's a motor area and its motor neurones innervate muscles of the mouth, larynx, intercostal muscles and diaphragm to produce sounds we call speech- if area is damaged= Broca's aphasia- understand speech but own may be slurred with incomplete, ungrammatical sentences Broca's and Wernicke's= in different lobes but are quite close to each other- arcute fasciculus is bundle of nerve fibres thought to link them- if damaged- can understand written and spoken words but can't speak |
| Studying the brain | Brain is studied using 3 main approaches- Clinical or neuropsychological assessment- non invasive- tries to correlate impairment of function w/ a damaged area of the brain after injury or neurological illness- assesses orientation, learning and memory, intelligence, language and visual perception- broad aim- diagnosis, understanding nature of brain injury, looking at changes over time |
| Brain studying- stim methods/ Brain imaging | Stimulation methods= invasive-electrical current is applied briefly to a specific area of the brain and effect is observed- patients= awake- assumption= applied current is equivalent to a natural event- effects mimic what happens normally- roles of speech and language areas of the brain have been identified / areas associated w/ Parkinson's, OCD and dystonia have been studies- Deep Brain Stim (DBS)- been used to treat those w/these conditions and others Brain imaging- non invasive- shows relationship between brain structures and their function |
| EEG | Uses electrodes on the scalp to detect voltage fluctuations in the brain - provides info about normal electrical activity -voltage fluctuations have been correlated w/ functioning of cerebral cortex and various types of behaviour- EEG helps diagnose some disorders/ can assist in prognosis of coma cases- allow monitoring of depth of anaesthesia during surgery- rhythm of a EEG trace are described by their frequency- EEG of adult is different from child- normal pattern varies throughout life- may have sharp waves/ spikes that are natural- but also may occur in seizure |
| EEG- pros and cons | - non invasive- subject doesn't get claustrophobic or have to stay still -Cheaper than other scanning methods -Better understanding of what, neurologically is being measured - Shows changes in brain activity over millisecond range unlike CT or MRI -EEG is not noisy/ doesn't use magnetic fields unlike CT/MRI- can be problem eg pacemaker - But- can only detect activity in cortex/ unlike PET can't identify synapses where drugs/ neurotransmitters act - |
| CT | Also called CAT- Many X-ray images taken from different angles= combined using sophisticated software- produces- high resolution cross sections or tomographic images= 'virtual slices'- make it possible to see inside the body without cutting Can detect tumors, brain injuries eg skull fractures and can identify a haemorrhage/ blood clots which c an cause strokes |
| CT pros/ cons | Whole body scan can be done in seconds- virtual slices show areas of interest w/out ghost images or other structures- area can be viewed from different angles and image has high contrast- but radiation from CT scan may lead to cancer/ some may feel technique is greatly overused |
| MRI | Uses strong magnetic fields to align protons in water molecules - monitored as they move again, following a pulse of radio waves- produces detailed computer generated images of soft tissues and organs- investigate anatomy- many images= taken milliseconds apart- so can show how brain responds to stimuli- |
| MRI p2 | More sensitive than CT- shows some areas of the brain more effectively - so is used to image brain cancers and may be used in their surgery- gives good contrast between grey and white matter= useful for studying abnormal brain development/ demyelinating diseases/ cerebrovascular disease eg aneurysms and blood clots which can cause strokes |
| Functional MRI (fMRI) | investigates function rather than structure of tissues as it uses strong magnetic field and a radio wave pulse to construct BOLD (blood oxygen level dependent) images- oxyhaemoglobin and haemoglobin respond differently following radio pulse so fMRI shows the flow of oxygenated blood- statistics are used to construct a 3d map where areas of cortex that are responding to a particular stimuli produce a brighter area in the image due to greater demand of oxygen by active neurones- greater proportion of oxyhaemoglobin in the blood of those areas fMRI- assesses brain activity on a second to second basis=most common brain scan |
| fMRI- pros and cons | MRI/ fMRI- don't use ionising radiation- preffered to a CT- more expensive and time consuming- may be a problem for those w/ claustrophobia or those who're sensitive to loud noises - magnetic field- unsuitable for those who have metal in their bodies - but doubt over cost effectiveness and overdiagnosis |
| PET | use of radioactive glucose in a 3D map of brain- active areas using more glucose - release more radiation- computer translates into yellow and red- less active areas are coloured green and blue - can detect biochemical areas in the brain before anatomical areas that accompany brain injury occur |
| PET mechanism | Fluorodeoxyglucose-FDG- injected into patient- enters respiratory pathway- like glucose- phosphorylated by hexokinase- 18F present in FDG replaces oxygen atom in glucose that's needed for next step in glucose metabolism - no further reaction- FDG trapped in any cell that takes it up- 18F emits a positron- as it decays- travels less than 1mm- loses kinetic energy as it travels and collides into an electron- produces Y- rays- detected in the scanner |
| PET- uses | Diagnosis and monitoring of many cancers- most pet scans - most PET scans are used to identify cancer metastasis- Neuropsychology- PET scans confirm that during linguistic activities- areas in the left hemisphere- more active than those in the right/ some conditions eg Alzheimer's decrease rate of glucose metabolism- PET can diagnose Alzheimer's/ differentiate it from other forms of dementia |
| PET uses P2 | Psychiatry- some tracers bind selectively to brain receptors for dopamine, serotonin or opioids- healthy individuals can be compared to scz, substance abusers, mood disorders/ other conditions Radiosurgery- can be used to guide the surgical treatment of brain tumors |
| PET-pros and cons | have high operating cost and the scan must take place within a short time of the FDG radiotracer being synthesized before the isotope decays- subject is exposed to gamma radiation- receives about double the ionising- radiation dose of a CT chest scan |
| Neuroplasticy | wjec- The ability of the brain to modify its own structure and function following changes within the body or external environment- research shows that experience can change both the brain's anatomy and functional organisation- brain makes new neuronal connections throughout life in response to sensory info= aspect of neuroplasticity- involves many cell types and occurs in healthy development, learning, memory and recovery from brain damage |
| synaptic plasticity | ability of synapse to change its strength- eg changing the amount of neurotransmitter released or changing response in a post synaptic neurone = response to an alteration in frequency of use of synaptic pathways due to changes in behaviour, environment, neural processes, thinking and emotions- Synaptic plasticity has a sig role in learning and memory |
| Non synaptic plasticity/ synaptic pruning | Doesn't affect synapses but changes excitablity of axon, dendrites, cell body of a neurone eg changing voltage gated channels- could be response to bodily injury Synaptic pruning- elimination of unused synapses that happens between early childhood and maturity- ensures synapses left are efficient and strong- when repeatedly stimulated that pattern of neural connections become 'hard wired' - permanent pathway- cahnges can be seen w/ rain imaging |
| Brain development and language | There are periods in brain development when its most receptive to acquiring specific skills - if that window of opportunity is lost- very hard to learn skill subsequently- language needs extensive post natal experience to produce and decode speech sounds- hearing and practice are crucial- deafness without expression eg signing and repeated ear infections in first few years can delay language development |
| Brain development and language P2 | Infants initially distinguish the sounds or phonemes of all languages- during brain development experience selects certain synapses related to phoneme production and perception- as infants hear phenomes different clusters of neurones in auditory cortex of brain respond to each sound- absence of certain phenomes results in loss of synapses representing those sounds- decreased ability to perceive them 1-2 yrs- brain organises synapses associated with language- up to 5yrs brain learns syntax of grammar- after 5yrs brain is able to learn new words throughout life |
| Genes, brain development and behaviour | As an organism grows- chem reactions eg changes in methylation of DNA and acetylation of histone proteins, occur that up- or down regulate parts of the genome at particular times/ locations- environmental factors also have direct impact on epigenetic effects (control of gene expression by modifying DNA or histones but not affecting DNA nucleotide sequence)- epigenetics can affect physiology - eg children of women malnourished when pregnant had an increased susceptibility to obesity and diabetes- epigenetic regulation of brain development= unique to mammals- epigenetic changes in brain cells can link to mental illness/ addiction |
| Gene expression and mental illness | family and twin studies show genetic factors have a role in the development of psychiatric disorders- genetic approach s focussed on genetic polymorphisms - but doesn't explain extent and variation in psychiatric illnesses that occurs- many conditions are polygenic and the interaction of these many genes w/ each other and the environment when contributing to a disease- may be succeptible to condition but not inherit it |
| Gene expression and mental illness P2 | mental disorders= complex-Epigenetic causes have a variety of origins - can effect: -size of certain brain regions- BPD linked w/ increased amygdyla volume -Neurotransmitter systems- abnormal neurotransmitter have been linked w/ scz, adhd, ocd, phobias, ptsd etc - drug use- alcohol can damage white matter in the brain- can effect thinking/ memory and cause depression- amphetamines/ LSD can cause paranoia and anxiety Childhood experience-abused children= more likely to get severe depression, psychiatric disorders/ recovery is poorer |
| Mental illness and cortisol | Increased stress causes: -increased release of cortisol from adrenal glands into blood- cortisol production is controlled by hippocampus via HPA (hypothalamus- pituitary- adrenal) axis -in response to stress- hippocampus sends nervous impulses to the hypothalamus- releases 2 hormones= corticotrophin-releasing hormone and arginine vasopressin (ADH) |
| Mental illness and cortisol p2 | 2 hormones stimulate the anterior lobe of the pituitary gland- releases adrenocorticotrophin (ACTH) into the blood- when adrenal glands take up ACTH they release cortisol- circulates in the bloodstream- binds to glucocorticoid receptors of the hippocampus- responds- sends inhibitory nervous impulses to the hypothalamus - reducing cortisol secretion |
| More stress | cortisol production is controlled by negative feedback- release of cortisol into the bloodstream- results in decline of cortisol production- stops us from being constantly overstressed-produce too much cortisol over time- feedback loop is overriden- either hippocampus or hypothalamus don't respond properly to high cortisol levels- so- continued production of corticotrophin-releasing hormone- gives higher background stress level- part of being more vulnerable to mental illness |
| Behaviour- definition/ innate | Behaviour- describes range of actions made by individuals in relation to themselves or their environment Innate behaviour- inborn complex patterns of behaviour that exist into members of a species- instinctive- innate behaviour- more significant in animals in less complex nervous systems- less ability to learn and modify their behaviour |
| innate behaviour- examples | Reflex= rapid, automatic, protective response to a given stimulus- improves chances of survival Kinesis- movement of a whole organism- not in particular direction in relation to a stimulus-include response to light intensity, humidity and temp- individual moves faster/ slower and changes direction w/ different frequency- same species- same response- brings them together- attracted to each other- orthokinesis- movement depends on intensity of a stimulus eg decreased humidity- woodlice move more |
| innate behaviour- examples p2 | Taxis- Taxes involve the whole organism moving in response to a stimulus, where the direction of the movement is related to the direction of the stimulus- positive- toward/ away- negative- organisms may sample the environment- all over the body to determine the direction of a stimulus or may use bilateral sense organs to do so- taxis is named for the stimulus eg chemotaxis- bacterium-E Coli- positive chemotaxis swims up conc gradient of glucose |
| Learned behaviour P1- habituation/ imprinting | Learning can be defined as a relatively permanent change in behaviour due to past experience. Learning allows behavioural responses to be modified. • Habituation involves learning to ignore stimuli because they are followed neither by reward or punishment. • Imprinting is a type of learning that occurs during a very early or receptive stage (critical periods of brain development) in the life of birds and some mammals. The young of birds, and some mammals, respond to the first larger, moving object they see/smell/touch/hear. They attach to this object and the attachment is reinforced by ‘rewards’ such as warmth and food. As exemplified by the experiments of Konrad Lorenz- studied geese- imprinting on same species is important when animal needs to find suitable mate later |
| Learned behaviour P2 | Associative behaviours include classical and operant conditioning. In these types of behaviour animals associate one type of stimulus with a particular response/ action Classical conditioning involves the association between a natural and an artificial stimulus to bring about the same response. As exemplified by the experiments of Pavlov. • Operant conditioning involves the association between a particular behaviour and a reward or punishment (use of reinforcers). As exemplified by the experiments of BF Skinner. |
| Learned behaviour P3 | Latent (exploratory) learning is not directed to satisfying a need or obtaining a reward. Many animals explore new surroundings and learn information at a later stage and mean the difference between life and death. • Insight learning does not result from immediate trial and error learning but may be based on information previously learned by other behavioural activities. shown- experiments of Kohler- chimpanzees - fruit given just out of reach- given sticks and boxes and they eventually found methods of climbing and knocking it down-learning via personal interactions w/ environment |
| Learned behaviour P4 | Imitation is a form of social learning allows learned behaviour patterns to rapidly spread between individuals and to be passed down from generation to generation. It involves copying the behaviour of another animal, usually a member of the same species. Differences can arise between populations as a result of imitation of different behaviour patterns in different areas; these are cultural differences e.g. Chimpanzees cracking nuts - some populations use stones, others use sticks/branches |
| Living in social groups | Social behaviours involve interactions between individuals of the same species and many species form highly structured social groups (societies). Within these groups the behaviour of one individual can influence the behaviour of others within the group |
| Social groups- communication | Social behaviour relies on the ability of animals to be able to communicate with one another. There are various ways that animals can communicate but they always involve one individual producing a signal (sign stimulus) that can be detected by another; this may trigger an innate response in the second individual. Eg the begging response of a gull chick is triggered by the red spot on its parent’s beak. • These are often referred to as stereotyped behaviours or fixed action patters (FAPs) and the sign stimulus activates nerve pathways which bring about coordinated movements without any decision making in the brain-cerebellum= heavily involved in FAP's- co-ordinates rapid, detailed movements w/out conscious thought |
| More on social groups | • Stereotyped behaviours involving FAPs are more complex than simple reflex actions and can be modified by experience. There's innate FAP's eg newborn crying/ yawning and learned FAP's eg those to produce leg motions for walking/ bike riding The response of the individual is dependent upon its motivational state. For example: if a cheetah is hungry (motivational state) it will initiate stalking behaviours upon the sight of prey (sign stimulus); if the cheetah is not hungry the sight of prey does not induce stalking behaviours. |
| Insect social structures | Ants, bees and termites are social insects living in colonies which are organised based on a caste system. • Typical insect colonies contain thousands of individuals, which are all closely related, but they are divided into different groups (castes) with specific roles. In a honeybee colony there is a single fertile female (the queen), several thousand sterile female workers and a few hundred fertile male drones. One caste may find food, while others care for young or defend the colony. The success of insect societies is largely due to the division of labour which increases the overall efficiency of the group. • Communication between individuals within the colony is by touch, pheromones and by visual orientation displays known as dances. |
| Eusocial colonies | Bees/ wasps/ termites fall into this- use castes system- has brood care- tend to offspring of other individuals Overlapping generations in a colony Division of labour- specialised groups- castes Most efficient type of colony |
| honeybee communication | Studied by Karl Von Frisch Worker bees forage for sources of nectar and communicate the distance and direction of the source to other workers by the nature of a dance performed on a vertical surface on the inside of the hive or on the floor at the hive entrance. The worker performs a round dance which indicates that the source of food is less than about 70m from the hive but gives no indication of direction. The waggle dance is performed if the source is greater than about 70m and also includes information as to its distance from the hive and its direction relative to the hive and the position of the sun. |
| Honeybee genetics | Caring for young of others- explained by female workers and brood they raise share 75% genes rather than 50% shared genes by diploid siblings of diploid parents- workers are diploid- 50 % genes- come from male who being haploid gives all genes to each species- same in every worker- other 50% comes from queen- diploid- gives 50% of hers to each- each worker has a different 50% from the queen- so on average will share 25% of same queen genes w/ other workers |
| Honeybee genetics summary | So- 50 % worker bee genes are same as other workers- come from father, 25% genes are same that come from mother- 75% identical- same genes don't provide complete exp for eusociality as not all eusocial animals have this trait and some species that do aren't eusocial |
| Vertebrate social structure | Vertebrate social interactions range from solitary to big social groups- social groups eg birds and fish have evolved independentely many times- social groups exhibit one or more of these behaviours -co-operative rearing of young overlapping generations living together permanently cooperative foraging or hunting cooperative defence against predators social learning 3 types of social group egalitarian, despotic and linear (dominant) |
| Vertebrate social structure- dominance heirarchy | Egalitarian- all individuals have equal rank, Despotic 1 member= dominant- all others equally submissive In vertebrates, social groups tend to be based upon dominance hierarchies; higher ranking individual are dominant over lower-ranking ones. Most dominance hierarchies are linear i.e. they have no members of equal rank; for example a group of hens sharing a hen-house. • Dominance hierarchies only exist where animals are able to recognise each other as individuals and possess some ability to learn. |
| Dominance heirarchy advantages | -It decreases the amount of individual aggression associated with feeding, mate selection and breeding site selection and ensures that resources are shared out so that the fittest survive- heirarchy= stable- maintained by aggression- fighting= last resort- alternatives= series of rituals where each action acts as a sign stimulus for next action of other animal |
| Dominance advantages p2 | Advantages for the dominant individual includes Greater access to mates- high ranking females produce more surviving offspring, dominant pairs have greater access to water/ food/ best territories (both offspring and adults have better health), |
| Dominance disadvantages | May be that dominant animals have more stress than those in subordinate ranks- high stress can cause higher conc of cocorticoids in blood- linked to disease- may be in part why subordinates rarely challenge position |
| Territorial behaviour | Territory= area that animal consistently defends against other members of species Territorality is only shown by a minority of species- more commonly an individual or group of animals will use an area (home range) that it doesn't necessarily defend Territory increases animals ability to reproduce- provides food, nesting sites / mating areas Many create signposts in their territory to advertise: occupied territory, their sex/ reproductive status, dominance status of territory holder |
| Territory behaviour p2 | Communicate info via smell, light and sound Scent marking- uses urine, faeces or specialised scent glands- can indicate presence of territory holder to prey species Visual signposting- colouration of the animal or long term visual signals eg faecal deposits Vocalisation- used to advertise territory- eg show that certain area is theirs Animals used ritualised aggression to defend territory w/out fighting- if intruder invades both animals begin ritualised aggression w/ postures, vocalisations and displays g showing claws usually ends w/ individual (usually intruder) fleeing- if not fighting can occur as last resort |
| Courtship | Courtship is used to attract a mate. Courtship allows recognition of species, sex and sexually mature/receptive individuals; stimulation and synchronisation of sexual behaviour. • Courtship routines are innate thus they ensure intraspecific mating and therefore likely to produce fertile offspring. • Many species show sexual dimorphism – the males and females look different e.g. peahens and peacocks |
| Courtship | When animals choose mate 2 opposing forces operating over generations Sexual selection and natural selection will be working against each other – sexual selection will make a characteristic more conspicuous(and so more attractive)- alleles for more exaggerated form of the characteristic= selected- transmitted to next gen natural selection will try to make it less conspicuous- those w/ an exaggerated form- more likely to be predated upon- fewer offspring to carry relevant alleles |
| Sexual selection | s. There are two main theories behind the driving force of sexual selection: • Intra-sexual selection/male-male combat: In species such as African lions, and southern elephant seals the males are much bigger than the females. In these species the males fight for sexual access to many females. Sexual selection has therefore favoured the evolution of larger more aggressive males. |
| Sexual selection p2 | Inter-sexual selection-male starts courtship female decides either to mate or reject this can be further divided into the physical attractiveness model and the male handicap model PAM-more attractive- more likely to be chosen- eg physical features act as sign stimulus- red patch on throat- attracts females/ causes aggression in males- more colouration- better chance- also mating dance-many cases- usually male performing- key stimulus for this FAP is the presence of the female, and she chooses her mate based on how elaborate his plumage is and how well he can boogie down. Male handicap-sexual dimorphism can occcur- theory suggests reliable signals eg lion mane, colourful peackock feathers are seen as costly to male- extravagant signal wouldn't be wasted on inferior male- suggests quality to female |
| FAP's- greater exp | Fixed action pattern (FAP) is an instinctive behavioral response that is triggered by a very specific stimulus. Once triggered, the FAP behavior can’t be stopped ‘midstream’, but must play out to completion. Fixed action patterns are produced by a neural network known as the innate releasing mechanism. The FAP is triggered in response to an external sensory stimulus known in animal behavior terms as a sign stimulus, or, if it is a signal from one individual to another, it is called a releaser. eg When the female notices an egg outside the nest (sign stimulus), she begins the repeated movement to drag the egg with her beak and neck. |
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