AOS1

• What is the Spinal Cord?

  The spinal cord is a 45cm long extension of your brain stem which is connected to your peripheral nervous system by pairs of spinal nerves. These consist of bundles of fibres, which connects them to various parts of the body, as well as sensory and motor pathways.
• what is the role of the spinal cord?

  • Relays sensory and motor information between the CNS and PNS
  • involuntary responses, such as spinal reflexes.
• role of CNS

  • Receives, processes, integrates, and coordinates responses to sensory stimuli from the PNS and transmits motor information back
• Brain

  • Control center
  • receives, processes sensory stimuli, and coordinates psychological and physiological responses
• PNS

  • All nerves outside the CNS, carry information between the CNS and visceral muscles, organs, and glands
• Somatic Nervous System

  • Governs the skeletal muscles, carries sensory information to CNS and motor information to the body
  • enables deliberate movement by the body
• Autonomic Nervous System

  • Governs involuntary functions of the visceral muscles, organs, and glands
  • controls the body’s internal environment in an autonomous or self-regulated manner
• Sympathetic Nervous System

  • Increases arousal, readies the body for a quick response, activated in dangerous situations for survival function
  • directs blood supply to areas of the body requiring more activity
• Parasympathetic Nervous System

  • Maintains the optimal and balanced functioning of visceral muscles, organs, and glands
  • regulates heart and respiration (homeostasis)
• Conscious Response

  • Response of the NS that requires awareness
  • deliberate and voluntary action that is initiated by the brain and intentionally carried out by the body
• Unconscious Response

  • automatic and involuntary action that bypasses the conscious control of the brain or is independent of the brain
• Spinal Reflex

  • Unconscious and adaptive response initiated by interneurons in the spinal cord, independent of the brain
  • prevents damage
  • quick and involuntary
• Sympathetic Response

  • Pupils dilate to allow for more light to see
  • increases secretion of glucose from the liver to energise the body
  • redirects blood flow from internal organs to extremities
  • Adrenal glands secrete adrenaline and noradrenaline to energise the body and help deal with stress
  • Sweat glands activated for thermoregulation – cooling the body
  • Bladder relaxes for energy conservation
  • Digestion processes inhibited for energy conservation
  • Lungs/bronchioles dilate for more oxygen
  • inhibits release of bile from the pancreas for digestion
• Parasympathetic Response

  • Pupils constrict
  • Releases less glucose
  • Heart rate regulated/balanced
  • Adrenal glands do not secrete stress hormones
  • Sweat glands deactivated
  • Bladder constricts
  • maintains intestinal movement and stimulates salvary glands
  • Lungs/bronchioles regulated
  • maintains homeostasis - balance
• Neurotransmitters

  • Neuron-produced chemicals that carry messages to neurons or muscle/organ/gland cells
• Excitatory Neurotransmitters

  • Increased likelihood of postsynaptic neuron firing an action potential
• Inhibitory Neurotransmitters

  • Decreased likelihood of postsynaptic neuron firing an action potential
• Glutamate

  • Main excitatory neurotransmitter, involved with learning and memory
• GABA

  • Main inhibitory neurotransmitter, associated with anxiety, specific phobias, and Parkinson’s disease
• Neuromodulators

  • Alter the strength of neural transmission, moderates/regulates the responsiveness of neurons to neurotransmitter signals
• Main Neuromodulators

  • Dopamine
  • Serotonin
• Dopamine

  • Multifunctional neurotransmitter
  • Has both excitatory and inhibitory effects
  • Involved in movement, pleasure, attention, mood, cognition, and motivation
• Serotonin

  • Inhibitory neurotransmitter
  • Also acts as a neuromodulator
  • Involved in sleep and mood
• Differences between neurotransmitters + neuromodulators

  • Size of effect (large vs small)
  • Speed (slow vs quick)
  • Neuromodulators transmit to multiple neurons, neurotransmitters to one or maybe two
  • Neurotransmitters are either excitatory or inhibitory, neuromodulators can sometimes be multifunctional
• Synaptic plasticity

  • Specific changes that occur within the synapse, between neurons
  • Includes sprouting, rerouting, and pruning
  • Long term potentiation and long term depression are examples
• Sprouting

  Growth of axon or dendrite fibres at the synapse
• Rerouting

  1. Formation of new connections between neurons

  2. Establish alternative neural pathways
• Pruning

  1. Removal of excess neurons and synaptic connections

  2. Increases the efficiency of neuronal transmissions
• Long term potentiation

  1. Long lasting strengthening of synaptic connections

  2. Occurs through repeated coactivation of a neural pathway (pre-synaptic and post-synaptic neurons)
• Long term depression

  1. Long lasting weakening of synaptic connections

  2. Occurs through "sub-threshold stimulation" of the postsynaptic neuron
• Stress

  • Psychological and physiological experience caused by stressors that exceed our ability to cope
• Stressor

  • Anything in our internal or external environment that exceeds our ability to cope or demands attention
• Types of stressors

  • Internal stressor
  • External stressor
• Distress

  • Negative psychological experience of stress
  • Decreases performance
  • Undesirable outcome
• Eustress

  • Positive psychological experience of stress
  • Increases performance
• Physiological stress response

  • How the body reacts to a stressor
  • Includes cortisol as a stress hormone
• Acute stress

  • Stress that occurs because of a sudden/immediate threat
  • Lasts for a short time
• Chronic stress

  • Stress that lasts for a long time
  • Caused by a prolonged stressor
• Flight-fight-freeze response

  • Automatic biological survival response
  • Adaptive
• Cortisol

  • Stress hormone secreted by the adrenal gland
  • Initiates and maintains heightened arousal
  • Effects include energizing the body, increasing blood sugar levels, improving metabolism, and reducing inflammation (immunosuppression)