psych unit 3 AOS 1 Study Guide

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Nervous System

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The integrated network that detects, processes and responds to internal and external stimuli. It comprises the central nervous system and peripheral nervous system which together coordinate behaviour, mental processes and bodily regulation. Understanding its branches explains how the body interacts with the environment.

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Central Nervous System

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The brain and spinal cord that process information and coordinate bodily activities. The brain is the control center for mental processes while the spinal cord is the main communication pathway to and from the body. It integrates incoming sensory information and issues motor commands.

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Peripheral Nervous System

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All neural pathways outside the brain and spinal cord that connect the CNS to the body's organs and muscles. It is divided into the somatic system for voluntary actions and the autonomic system for involuntary regulation. It transmits sensory information to the CNS and delivers motor commands to effectors.

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Somatic System

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The PNS subdivision that controls voluntary movements and conveys sensory information to the CNS. It uses motor neurons to activate skeletal muscles and sensory (afferent) neurons to relay external stimuli. It underpins conscious interaction with the environment.

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Autonomic System

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The PNS subdivision that regulates involuntary bodily functions such as heart rate, digestion and glandular activity. It operates largely unconsciously and has two branches — sympathetic and parasympathetic — that maintain physiological balance. It supports homeostasis and automatic responses to stress.

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Sympathetic System

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The autonomic branch that activates the body for action in threatening situations, producing the fight-or-flight response. It increases heart rate, adrenaline release and glucose availability while diverting resources from non-urgent functions. Its activation is typically rapid and involuntary.

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Parasympathetic System

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The autonomic branch that promotes rest-and-digest activities and restores the body to a state of equilibrium after stress. It slows heart rate, enhances digestion and conserves energy to support recovery and maintenance. It counterbalances sympathetic activation to maintain optimal functioning.

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Neuron Types

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The principal neurons are sensory (afferent) neurons carrying information to the CNS, motor (efferent) neurons sending commands to muscles and glands, and interneurons that connect neurons within the CNS. Each type has specialised roles in processing and transmitting neural signals. Together they enable perception, reflexes and voluntary actions.

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Spinal Reflex

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An automatic, rapid motor response to a potentially harmful stimulus mediated by a reflex arc in the spinal cord without initial brain involvement. Sensory neurons send signals to interneurons in the spinal cord which elicit immediate motor output; the brain becomes aware afterward. This mechanism protects the body from injury.

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Neurotransmitters

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Chemical messengers released at synapses that transmit signals between neurons by binding to receptors on postsynaptic cells. They can be excitatory or inhibitory and are essential for neural communication underlying perception, mood and behaviour. Examples include glutamate, dopamine and serotonin.

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Synaptic Plasticity

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The brain's ability to strengthen, weaken or reconfigure synaptic connections in response to experience, learning or injury. Mechanisms include sprouting (forming new connections), rerouting (creating alternative pathways) and pruning (eliminating unused synapses). This dynamic change underlies learning, memory retention and recovery after damage.

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Long-term Potentiation

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A persistent strengthening of synapses following repeated stimulation that enhances signal transmission between neurons. LTP is considered a primary cellular mechanism for learning and long-term memory because it makes previously activated pathways more efficient. Opposite changes, like long-term depression, reduce synaptic efficacy.

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Dopamine

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A neuromodulator involved in voluntary movement, reward processing and learning via reinforcement. Deficient dopamine in certain brain areas is linked to Parkinson's disease, producing tremors, bradykinesia and postural issues. Treatments often aim to increase dopamine availability or mimic its action.

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Serotonin

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A neuromodulator produced mainly in the raphe nuclei that regulates mood, sleep and aspects of appetite and arousal. Adequate serotonin supports positive mood and good sleep quality, while low levels are associated with depression and disrupted sleep. Many antidepressant medications target serotonin levels or receptors.

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Stressor Types

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Stressors are events or demands that produce stress and can be internal, originating within the individual (e.g., attitudes, illness), or external, arising from the environment (e.g., exams, work pressure). Both types can trigger psychological and physiological stress responses depending on appraisal and context. Identifying stressor type helps tailor coping strategies.

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Eustress vs Distress

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Eustress is positive, motivating stress that can enhance performance, while distress is negative stress that impairs functioning. The same stressor can be experienced as eustress or distress depending on an individual's appraisal, resources and context. Emotional response determines whether stress is beneficial or harmful.

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Fight-or-flight-freeze

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An involuntary acute stress response mobilising the body to confront or escape threat (fight or flight) or become immobile (freeze). It involves rapid autonomic nervous system activation and prepares physiological systems for immediate action. The freeze response can include tonic immobility and is adaptive in certain situations.

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Cortisol

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A glucocorticoid hormone released during prolonged stress that helps sustain heightened arousal and mobilise energy. Chronically elevated cortisol can suppress immune function and contribute to negative health outcomes. It plays a central role in the physiological response to ongoing stressors.

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General Adaptation Syndrome

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Hans Selye's biological model describing predictable bodily responses to stress across three stages: alarm reaction, resistance and exhaustion. It explains physiological changes during acute and prolonged stress but overlooks individual psychological appraisal differences. The model highlights how prolonged stress depletes resources and harms health.

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Alarm Reaction

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The initial GAS stage consisting of shock, where arousal temporarily decreases, followed by countershock, when the sympathetic nervous system activates and arousal increases. This prepares the organism to respond to the stressor. It marks the body's immediate mobilisation of resources.

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Transactional Model

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Lazarus and Folkman's model emphasising that stress arises from the transaction between person and environment through primary and secondary appraisal. Primary appraisal judges whether an event is benign, irrelevant or stressful and secondary appraisal assesses coping resources. The model explains individual differences in stress responses and guides context-specific coping.

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Coping Strategies

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Methods used to manage stress, broadly classified as approach strategies that confront stressors and avoidance strategies that evade them. Coping flexibility is the ability to adaptively switch strategies depending on context and resources. Effective coping depends on the situation and available supports.

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Gut-Brain Axis

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The bidirectional communication system linking the gastrointestinal tract and central nervous system, influenced by gut microbiota composition. It can affect stress, mood, learning and behaviour, with emerging evidence connecting microbiota diversity to mental health outcomes. Research suggests gut health may modulate psychological functioning, though findings are still evolving.