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Neuroscience: Neurons and Synapses - VOCABULARY Flashcards

Refractory Period

  • Brief recovery period
  • Neuron must "catch its breath"
  • Cannot fire again immediately
  • Duration: less than one second
  • Ensures discrete signaling and prevents back-to-back firing

All-or-None Principle

  • Action potential either happens completely or not at all
  • Must reach specific threshold voltage: V_{ ext{th}}
  • Same intensity each time it occurs
  • Process takes less than one second
  • Prevents partial or graded action potentials across a single event

Graded Potential

  • Occurs when stimulus is not strong enough to trigger action potential
  • Unsuccessful/insufficient activation
  • No transmission occurs
  • Signals can vary in magnitude, but do not trigger an all-or-none spike

Synaptic Transmission

  • The Synaptic Process
  • Synaptic Cleft: Gap/space between two neurons where neurotransmitters wait to be received
  • Receptor Sites: Specific binding locations on receiving neuron
    • Lock-and-key mechanism: neurotransmitters must fit specific receptors
    • Examples:
    • Norepinephrine cannot fit dopamine receptors
    • Serotonin cannot fit dopamine receptors
  • Post-synaptic Membrane: The receiving neuron's membrane; contains receptor sites for neurotransmitters

Clinical Applications

  • Depression Treatment
    • Problem: Insufficient serotonin or lack of receptor sites
    • Solution: Medications increase number of serotonin receptors
    • Effect: Provides more binding sites for available serotonin
  • ADHD Treatment
    • Adderall provides norepinephrine and dopamine
    • Stimulant medication increases available neurotransmitters

Important Terms and Concepts

  • Heritability: Extent to which traits are determined by genes
  • Epigenetics: Environmental influence on gene expression
  • Action Potential: Electrical impulse in neurons
  • Neurotransmitters: Chemical messengers between neurons
  • Synaptic Cleft: Space between neurons
  • All-or-None Principle: Action potentials occur completely or not at all
  • Homeostasis: Body's balanced, resting state

Connections and Real-World Relevance

  • Activation-to-transmission chain: how electrical signals trigger chemical signaling at synapses
  • Receptor density and sensitivity influence neurotransmission efficiency
  • Pharmacological treatments align with receptor-targeting concepts (e.g., SSRIs, stimulants)
  • Understanding these processes informs clinical approaches to mood and attention disorders

Ethical, Philosophical, and Practical Implications

  • Pharmacological manipulation of brain chemistry raises questions about autonomy, consent, and long-term effects
  • Access to medications (e.g., antidepressants, ADHD stimulants) involves ethical considerations of equity and potential for misuse
  • Epigenetics highlights the impact of environment and lifestyle on gene expression and brain function
  • Balancing benefits of treatment with risks of dependence, tolerance, and neuroplastic changes

Numerical References and Formulas

  • Time durations explicitly described as "less than one second": t < 1 ext{ s}
  • Threshold concept represented as V_{ ext{th}} (threshold voltage)
  • Other quantities are described qualitatively within the notes (no additional numerical data provided in the transcript)