psych unit 3 AOS 1 Summary & Study Notes

🧠 Overview

This section summarises how the human nervous system enables interaction with the environment, the biological bases of learning and memory, and key neurochemical influences on behaviour and mental health.

🧩 Divisions of the Nervous System

The nervous system is split into the central nervous system (CNS) — brain and spinal cord — and the peripheral nervous system (PNS) — all other neurons. The PNS divides into the somatic nervous system (voluntary control of skeletal muscles) and the autonomic nervous system (ANS) (involuntary regulation). The ANS further subdivides into the sympathetic (arousal, fight-or-flight) and parasympathetic (rest-and-digest) systems that maintain physiological balance.

⚡ Neurons and Neural Transmission

Neurons are the basic units: sensory (afferent) neurons send information to the CNS, motor (efferent) neurons carry commands to muscles and glands, and interneurons connect neurons within the CNS. Neural communication occurs via synaptic transmission where neurotransmitters cross the synaptic cleft to influence postsynaptic neurons.

🔁 Reflexes: Speed vs. Awareness

A spinal reflex (reflex arc) is an automatic, unconscious response to harmful stimuli. Pathway: receptor → sensory neuron → interneuron in spinal cord → motor neuron → effector. The reflex bypasses conscious brain processing for rapid action; the brain becomes aware after the reflex has occurred.

🧪 Neurotransmitters & Neuromodulators

• Neurotransmitters act at specific synapses and can be excitatory (increase likelihood of firing) or inhibitory (decrease likelihood). Examples: glutamate (major excitatory; crucial for learning and LTP) and GABA (major inhibitory; prevents overexcitation).
• Neuromodulators (e.g., dopamine, serotonin) have broader, longer-lasting effects on neural circuits. Dopamine: important for voluntary movement, reward and reinforcement; deficits associated with Parkinson’s disease. Serotonin: involved in mood regulation and sleep; low levels implicated in depression.

🔧 Balance Is Critical

A healthy brain requires a balance between excitatory and inhibitory influences. Imbalances can impair cognition, mood, and motor control.

🔄 Synaptic Plasticity (Learning & Memory Mechanisms)

Synaptic plasticity refers to the capacity of synapses to change with experience. Key mechanisms:

• Sprouting: formation of new synaptic connections.
• Rerouting: forming alternative pathways after damage.
• Pruning: elimination of unused synapses to increase efficiency.
• Long-Term Potentiation (LTP): long-lasting strengthening of synapses following repeated stimulation — core mechanism for learning and memory consolidation.
• Long-Term Depression (LTD): long-lasting reduction in synaptic strength — important for forgetting or modifying memories.

Applications: repeated practice strengthens relevant synapses (LTP); disuse leads to weakening/pruning; relearning can be faster because residual pathways remain.

🧭 Integration & Interconnectedness

Brain regions are highly interconnected; learning and memory depend on coordinated activity across networks, not isolated structures. Neuromodulators tune network states for attention, motivation, and consolidation.

🪶 Cultural Memory Techniques

The text highlights mnemonic techniques, including Aboriginal and Torres Strait Islander memory methods, which use story, place-based cues and imagery to encode and retrieve information — demonstrating cultural contributions to effective memory strategies.

✅ Summary

Understand the hierarchical organization (CNS/PNS), neuron types, reflex architecture, neurochemistry (glutamate, GABA, dopamine, serotonin), and mechanisms of synaptic plasticity (sprouting, rerouting, pruning, LTP, LTD). These concepts explain how experiences shape brain structure and function, influencing behaviour and mental health.

🌪️ Stress as a Psychobiological Process — Overview

This chapter frames stress as an interaction between external/internal stressors, subjective appraisal, and physiological responses that together shape coping outcomes and health.

📌 Types of Stressors

• External stressors: events or environmental demands (exams, work, disasters).
• Internal stressors: internal states or perceptions (rumination, low self-esteem, illness). Stress responses vary: eustress (positive, motivating) vs distress (harmful, negative).

🧬 Physiological Stress Responses

Acute stress evokes the fight-or-flight-or-freeze response via the sympathetic nervous system; chronic stress increases cortisol, maintaining arousal but potentially suppressing immunity and impairing health if prolonged.

🧭 Selye’s General Adaptation Syndrome (GAS)

GAS outlines three physiological stages in response to prolonged stress:

• Alarm reaction: immediate response with two substages — shock (brief drop in functioning) then countershock (mobilisation; sympathetic activation).
• Resistance: body adapts and maintains heightened arousal to cope; resources are consumed and immune function may be suppressed.
• Exhaustion: resources depleted; vulnerability to illness and reduced coping. Strengths: explains predictable physiological pattern. Limitations: underplays psychological differences and appraisal processes.

🔁 Transactional Model of Stress & Coping (Lazarus & Folkman)

Stress depends on individual appraisal:

• Primary appraisal: is the stimulus benign-positive, irrelevant, or stressful? If stressful, is it harm/loss, threat, or challenge?
• Secondary appraisal: evaluation of coping resources and options — determines perceived ability to manage the stressor. Coping types:
• Problem-focused coping: tackle the source directly (e.g., planning, studying).
• Emotion-focused coping: manage emotional response (e.g., reappraisal, avoidance). Reappraisal occurs if the situation or resources change.

⚖️ Coping Flexibility & Context

Effective coping depends on context and the individual’s ability to shift strategies (coping flexibility). The same strategy may be adaptive in one context and maladaptive in another. Examples in disaster contexts illustrate approach vs avoidance choices and shifts toward confronting losses.

🧪 Gut–Brain Axis

The gut-brain axis is a bidirectional communication system: gut microbiota can influence mood, cognition, stress reactivity and vulnerability to psychiatric conditions. Evidence is emerging (animal and human studies) linking microbiota diversity with mental health, but findings are still developing and sometimes contradictory.

📝 Practical Implications

• Recognise individual differences in appraisal and coping — two people can respond very differently to the same stressor.
• Short-term adaptive responses (GAS) can become harmful if sustained (chronic cortisol exposure).
• Building coping resources and flexibility improves resilience; interventions can target appraisal, skills training, social support, and where relevant, biological factors (sleep, exercise, diet influencing gut health).

✅ Summary

Combine biological models (GAS) with psychological appraisal frameworks (Transactional Model) to fully understand stress. Consider physiological mechanisms (sympathetic activation, cortisol) alongside appraisal, coping strategies, and emerging psychobiological influences such as the gut–brain axis.