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Explain the effects of THC and cocaine in terms of their action at synapses in the brain.
incl MOOD And behaviour
- blocks reabsorption o dopamine and noradrenalin at synapses in brain
- = increased energy alertness, talkativeness
- Cocaine causes continuous transmission at these synapses, resulting in feelings confidence intense euphoria not related to any activity
- May cause fear, jitters, and feelings o aversion
- Addiction may be caused by artificially high lvls o dopamine, neurons may even create new receptors for dopamine
- Increased sensitivity produces depression and cravings if cocaine lvls drop and dopamine lvls return to normal
- Body may also adapt to cocaine use by reducing secretion o dopamine;= cocaine induced depression
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THC / cannabis
- chemical THC binds to cannaboid receptors in various parts brain blocks synaptic transmission
- Impairs synaptic transmission by reducing amount o excitatory neurotransmitters released;
- THC is inhibitory psychoactive drug
- Users claim increase intensity sensory perception, gives feeling emotional well being + allows clear thinking about complex ideas (no evidence)·
- Evidence indicates actually impairs ability concentrate, control muscle contractions and judge times and distances (not safe to drive)
- Short term effects include memory impairment, intoxication and appetite simulation
- Long term uses may show attention deficits, memory loss and impaired learning ability
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addiction
- Psychoactive drugs are often associated with ‘addictive behaviour’.
- Addiction includes habitual behaviourCraves the use of the drug
- Cannot exercise self control in limiting the taking of the drug
- Habituation means that increasing quantities must be taken to achieve the same mental conditions
- Show side effects of talking the drug and withdrawal behaviour if unable to satisfy the craving.
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Discuss the causes of addiction, including genetic predisposition, social factors and dopamine secretion (3)
 - some genes make it easier family addicted,
- dependent on the feelings that dopamine promotes.
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label Diagram of the human brain
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Functions of brain regions (5)
- Medulla oblongata: Controls automatic and homeostatic activities, such as swallowing, digestion and vomiting, breathing and heart activity
- Cerebellum: Coordinates unconscious functions, such as movement and balance, including hand eye coordination
- Hypothalamus: Maintains homeostasis, coordinating nervous and endocrine systems, producing hormones tt are secreted by posterior pituitary gland; sends releasing factors to stimulate hormone secretion by anterior pituitary gland
- Pituitary gland: Posterior lobe stores and releases hormones produced by hypothalamus, anterior lobe produces and secretes hormones regulating many body functions
- Cerebral hemispheres: Receives impulses fr eye, ear, nose and tongue, act as integrating centre for higher complex functions such as learning, memory and emotions
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waggle dance
- workers communic by performing round (nearby food) or waggle dance (far food)
- workers interpret dance
- angle indicates angle food fr horizontal direc o sun and number times waggle = dist o food src
- may also regurgitate some nectar
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explain How brain lesions, animal experiments, and fMRI explain the function of specific brain regions (1 ex of each)
- fMRI (functional magnetic resonance imaging) shows areas of the brain which have increased blood flow.
- strong magnet measures number hydrogen atoms absorb then emit EM energy, diff types of tissue send diff signals
- Increased red blood cell oygenation = (BOLD) contrast, is associated with increased neurone activity
- trans into 3d images tt record regions o brain most active
- presented with a stimulus the fMRI is taken and the region of the brain with increased blood flow is linked to with the processing
- e.g. language thinking, find parts assoc with
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lesions
- lesions = damaged areas o brain
- brain damaged patients show certain symp/functional disabilities
- post mortem autopsies on stroke victims can associate particul brain area with symptoms
- e.g. role of sight in visual cortex, rear o cerebral hemisphere = soldiers surviving bullet wounds in rear o skull
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animal experiments
- removal of parts in healthy brain
- resulting behaviour ->
- e.g. severing fibres tt cross = clues interaction left and right halves
- destroying pons in the brain of cats, died from sleep deprivation, linked with being able to fall asleep
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explain Sympathetic and Parasympathetic Nervous control o heart rate, movements iris, blood flow to gut
- ANS part o peripheral nervous system tt used to control internal organs unconsciously
- two parts, which have roles tt are largely antagonistic (opposing)
- Parasympathetic motor neurons: keep organs in suitable state for non-threatening situations; normal relaxed state
- Sympathetic motor neurons: prepares organs for vigorous physical activity in response to threats or opportunities; “fight or flight” (Effects are similar to adrenaline)
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heart
- para: Heart rate is slowed as the body is relaxed and less blood flow is needed.
- symp: Heart rate speeds up so that more blood can be pumped to the muscles.
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Blood flow to gut
- para: Blood vessels are dilated, increasing blood flow in gut
- symp: Blood vessels are constricted, decreasing blood flow to gut
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Iris of the eye
- para: Circular muscle fibres contract, so pupil constricts to protect retina
- symp: Radial muscles contract, dilating the pupil to give a better image
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explain The pupil reflex
- ANS function illust by cntrl iris diaphragm reflex
- controlling amnt light = import, if too little, cones not stimul for effective sight, if too much = damage overstimul/ loss sight
- muscles iris reg pupil size
- circular muscle fibres innervated by para syst, contracted, radial relaxed, small pupil and amnt light
- radial muscle fibres innervated by symp, contrated, big pupil, circle relaxed
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discuss concept Death and the pupil reflex in testing for
- death on a biological lvl
- determine if the brain is still functional stimuli are presented such as shining light into the eye and looking for the associated pupil reflex
- if yes, indicate some function at the basic brain level of the medulla oblongata
- event of death cardiac output and ventilation can be maintained artificially, could use body for organ donation but must clarify brain death
- Absence of the pupil reflex indicates no basic brain function and allow surgeons to progress towards harvesting organs
- depends on ones definition of 'living' and on local and national laws.
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outline Pain perception and the role of endorphins
- pain recep located in skin + other organs, nerve endings perceive stimuli sent to sensory areas o cerebral cortex = feeling o painfeelings nec to know when body damaged, avoid action, pain withdrawal
- however, sometimes excessive + hinders important survival
- pituit gland released endorphins, carried in blood to brain, bind to receptors in membr neurons tt send pain impulse + block release neurotrans
- stressful times, after injury or running
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