Psychology AOS 3 SAC 1

Central Nervous System/ Role of Brain/ Spinal cord

• Central Nervous System: consists of brain and spinal cord

  • processes info, and initiates responses

• Brain:

  • Receives/ processes sensory info sent via spinal cord from PNS

  • Initiates appropriate responses

• Spinal Cord:

  • Receive sensory info from PNS and sends it to brain

  • Receive motor information from brain, sending it to relevant areas of body via motor neural pathways.

Peripheral Nervous System/ Role of Nerves/ Neruons

• Peripheral Nervous System: Consists of all the nerves/ neurons outside of CNS

  • Carries sensory info spinal cord

  • Carries motor info from spinal cord to muscles, organs and glands

Somatic Nervous System

• Division of PNS

• Made up of:

  • Sensory/ motor neural pathways

• Role: Voluntary movement

• Sensory info detected by sensory receptors, traveling to CNS

• Motor info travels from CNS to skeletal muscles

Autonomic nervous system

• Division of PNS

• Role: Involuntary movement

  • Self regulation of innate visceral muscles, organs and glands

    • transmit messages to CNS about their activity.

Sympathetic nervous systems

• Division of autonomic NS

  • Involuntarily activates visceral muscles, organs, and glands to respond to a threat/ stressor

    • etc. fight and flight response

    • widened pupils, increased heart rate/ blood pressure.

Parasympathetic nervous system

• Division of autonomic NS

• Maintains/ balances body’s internal environment, restoring it to a state of “calm” after heightened arousal.

  • freeze response

  • constricting pupils, slowed heart rate, increased digestion.

Spinal reflex

• Unconscious response to sensory stimuli, for faster reaction time, not involving brain

  • Sensory info travels to spinal cord

  • Interneurons in spinal cord coordinate response

  • Motor info sent to specific area (in body) causing muscles to contract.

• Individual not aware until after response

• involves somatic NS

Neurochemicals

• Chemical modules transmitting neural info within NS

  • Synaptic vesicles released from axon terminals of presynaptic neuron

  • Travels through synaptic gap,

  • Received by receptor sites of dendrites on postsynaptic neuron

• Effects postsynaptic neuron, either triggering/ inhibiting responses.

Neurotransmitters

• Produce excitatory/ inhibitory effects

• Affect 1-2 postsynaptic neurons

• Fast - compared to neuromodulators

Neurotransmitters - Glutamate/ GABBA

• Glutamate: Excitatory effects

• Increasing firing of action potential form postsynaptic neuron

  • Aids in memory/ learning, movement

  • strengthens synaptic connections

• GABA: Inhibitory effects

• Decreases firing of action potential from postsynaptic neuron.

  • decreases likelihood of seizures/ anxiety (prevents neurons from overexcitement)

Neuromodulators

• Produce excitatory/ inhibitory effects

• Affect multiple postsynaptic neurons

• slow - compared to neurotransmitters

• Effects brain and neurotransmitters:

  • Influences responsiveness of receptor sites on postsynaptic neuron

  • Release pattern of neurotransmitters

Neuromodulators - Dopamine/ Seratonin

• Dopamine: Excitatory/ inhibitory

  • Role in = pleasure, motivation, reward based behaviours, and voluntary movement

    • Low levels over prolonged period - can lead to depression

• Serotonin: Inhibitory/ excitatory

  • Role in = Mood/sleep

Synaptic plasticity: Sprouting, Rerouting, Pruning

• Ability for synaptic connections to change in response to activity/ experience

  • Sprouting: Dendrites/ axons develop new branches/ extensions

  • Rerouting: Neuron creates alternate synaptic pathway to avoid damaged neuron

  • Pruning: Removal/ elimination of synaptic connections that are not adequately activated

    • more efficient neural pathways

Long term potential (LTP): Structural changes

• Long lasting strengthening of synaptic connections from frequent activity

  • Creates more efficient synaptic connections.

• Increased no. receptor sites on dendrites of postsynaptic neuron

• Bushier dendrites on postsynaptic neuron (sprouting)

• Increased synaptic connections (sprouting)

Long term depression (LTD): Structural changes

• Long lasting decrease in strength of synaptic connections from infrequent activity

• Decreased no. of receptor sites on dendrites of postsynaptic neuron

• Decreased no. of dendrites on postsynaptic neuron (pruning)

• Decreased synaptic connections (pruning)

Stress: Internal/ External stressors

• Psychological/ Physiological experience in which something significant (stimulus), involves full effort and attention to cope.

• Internal:

  • Stimulus from within the body

    etc. low self esteem, rumination, NS dysfunctions (GABA dysfunction)

• External:

  • Stimulus from outside the body

  • etc. Exams/ SACS, work, studying

Differences between acute/ Chronic stress/ reactions

• Acute stress:

  • short term

• Chronic stress:

  • Long term

• Physiological reactions to stress (etc. Increased heart rate) are common, whereas psychological reactions are subjective- unique to individual

Different types of stress

• Eustress:

  • Positive psychological stress response

• Distress:

  • Negative psychological stress response

Fight-Flight-Freeze response in acute stress/ Nervous systems involved

• Fight-Flight- Freeze: Involuntary, immediate physiological reaction in response to a threat/ stressor

• Fight- Flight response:

  • Sympathetic NS

• Freeze response:

  • Parasympathetic NS

Freeze response characteristics

• Occurs individual feels the threat cannot be managed via the Fight/ Flight

  • Tonic Immobility = Immobilised state, Body conserves energy, redirecting it to organs

Sympathtic adreno-medullary system (SAM): Acute stress response

1. Threat perceived: Signal sent via the Amygdala to the Hypothalamus in brain

2. Sympathetic NS activated, and Adrenal Medulla stimulated

3. Adrenal medulla secretes stress hormones/ through bloodstream (etc adrenaline/ noradrenaline)

4. Body experiences heightened arousal due to activation of organs in Sympathetic NS

Cortisol: Benefits/ limitations

• Hormone released during stress, aiding the body in Initiating/ Managing heightened arousal

• Benefits:

  • Increased blood sugar, increases metabolism, energizes body, reduces inflammation

• Limitations:

  • Immunosuppression - reduces immune system

The Hypothalamic-Pituitary-Adrenal system (HPA axis): Chronic stress response

1. Hypothalamus stimulates Pituitary gland

2. Pituitary gland secretes ACTH hormone into bloodstream, carrying ACTH hormone to Adrenal cortex

3. Adrenal gland releases cortisol, increasing energy supply (blood sugar).

4. when Cortisol reaches certain level, Hypothalamus signalled and “switches off” the HPA axis response

Gut Brain Axis (GBA): Microbiome/ Microbiota

• Bi-directional system, in which gut can influence the brain (80-90%) , and the brain influences the gut (10-20%)

• Microbiome: All bacteria that lives in the gut. Healthy microbiome = rich and diverse microbiota

Enteric nervous system/ Vagus Nerve

• Enteric NS: Network of nerves within the gut, and is a subdivision of autonomic NS. Therefore can communicate with nerves in CNS

• Vagus nerve: Cranial nerve, branching out from brain stem (Medulla), connecting to the gut.

Gut brain axis (GBA): Its influence on Mood/ Stress

Changes in gut microbiota can disrupt:

• Can decrease diversity of beneficial bacteria

• Inhibits growth of beneficial gut bacteria responsible for production of neurochemicals etc. serotonin.

• While mental illness can influence your gut health.

Selyes General Adaption Syndrome (GAS)

• Biological model that tracks physiological responses to stress over a prolonged period of time, resulting from persistent stressor

• Consists of 3 stages:

  • Alarm reaction - shock/ countershock

  • Resistance

  • Exhaustion

Alarm reaction stage: Shock/ Countershock substages

• Immediate response, with initial decrease then increase in bodily arousal to a stressor

• Shock:

  • Body resistance to stress falls below normal functioning etc. decreased heart rate, low blood pressure

  • Momentary

• Countershock:

• Sympathetic NS dominates, while stress hormones are released into bloodstream (cortisol, adrenaline)

• Increased bodily arousal

• limited instant effect

Resistance stage/ Biological effects

• Maximises bodies resources, to maintain heightened arousal in response to persistent stressor

  • Maintains high levels of arousal due to high cortisol production

    • However long term cortisol= Immunosuppression (may experience minor illnesses)

Exhaustion stage/ Biological effects

• Body becomes vulnerable/ weak. Energy levels/ Bodies resources deplete, causing inability to cope with the stressor

  • Cortisol levels deplete

  • Bodily arousal decreases

  • Long term Immunosuppression = Fatigue/ Major illness/ Mental health disturbances

Strengths/ Limitations of General Aspation Syndrome (GAS)

• Strengths:

  • Recognised relationship between chronic stress/ illness

  • Recognises predictable pattern of physiological reactions to stress

• Limitations:

  • Not generalised to humans - conducted on rats

  • Only focuses on biological responses to stress

Lazarus and Folkman’s transactional model of stress

• Psychological model, explaining how mental processes influence a response to a stressor

  • = Transaction between an individual/ their environment

  • occurs in 2 stages:

    • Primary appraisal

    • Secondary Appraisal

Primary/ Secondary appraisal

• Primary: Evaluates the nature of incoming stressor/ type of stress it might cause

  • Benign - positive

  • Irrelevant

  • Stressful - Threat/ Harm/ Challenge

• Secondary: Evaluation of coping options/ resources for dealing with stressor

  • Can be internal (etc.determination) or external (money/family)

  • Not enough coping resources = stress, adequate coping resources = reappraisal/ eliminated stress

Strengths/ limitations: Lazarus and Folkman model

• Strengths:

  • Acknowledges psychological responses to stress

  • Emphasises subjective nature in perception of stress

• Limitations:

  • May not recognise all the factors that cause stress

  • Does not take into account physiological (biological) responses

  • Cannot be tested - too subjective

Emotion focused/ vs. Problem focused coping skills

• Emotion focused: Coping strategies that targets the emotional component of a stressor, dealing with it indirectly.

  • e.g wishful thinking, optimism, distraction

• Problem focused: Coping strategies that directly target the source of the stressor, aiming to reduce it.

  • e.g taking action, time management

Context specific effectiveness/ what it is dependant on

• When the coping strategy used, appropriately meets the demands of the stressor. (coping flexibility increases CSE)

• Depends on:

  • Situational determinants (environment)

  • Personal characteristics

Coping flexibility: how to apply it

• Recognising when current coping strategies are ineffective and, adjusting one’s coping strategy to meet the demands of a stressor

  1. Selecting a coping strategy

  2. Recognising strategy is ineffective

  3. Discontinue using ineffective strategies

  4. Implement alternative coping strategy

Approach/ Avoidance strategies

• Approach: Effort to confront stressor, dealing with it/ its effects directly

  • more adaptive compared to avoidance

• Avoidance: Effort to evade stressor, dealing with it/ its effects indirectly

  • Reliance on avoidance strategies= negative consequences (mental health)

  • maladaptive

  • only effective short term