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Psychology: Course Context and Core Definitions
  • Psychology is the scientific study of behavior and mental processes.
  • Course context: Chapter 3 in Psych 10/10 and 10/20 textbook.
  • Branches: Social, Personality, Clinical psychology.
  • Approaches: Psychodynamic (unconscious), Biological (neuroscience, brain, physiological processes).
  • Chapter preview: nervous system, neurons, brain structures, genetics, health and wellness.
The Biological Approach: Overview and Key Focus
  • Emphasizes the brain and nervous system's impact on behavior, emotions, and mental processes.
  • Covers: nervous system, neurons, brain structures, the brain, genetics and behavior, health and wellness.
Neuroscience and Electrochemical Communication
  • Neuroscience: study of the body's electrochemical communication circuitry.
  • Core claim: brain and nervous system significantly impact behavior, emotions, and mental processes.
  • Electrochemical transmission: information communicates via electrical impulses and chemical messengers.
Nervous System: Four Core Characteristics
  • Complexity: Highly complex system enabling everyday activities.
  • Integration: Brain integrates external information into a coherent experience.
  • Adaptability (Plasticity): Brain's physical capacity for change.
  • Electrochemical transmission: Signals passed via electrical impulses (neurons) and chemical messengers (neurotransmitters).
Afferent vs Efferent Nerves (Sensory vs Motor)
  • Afferent nerves: Carry signals from the body to the brain (sensory input).
  • Efferent nerves: Carry signals from the brain to the body (motor output).
CNS and PNS: Major Divisions
  • Central Nervous System (CNS): Brain and spinal cord (about 99% of neurons).
  • Peripheral Nervous System (PNS): Nerves connecting CNS to the rest of the body.
    • Somatic nervous system: Carries sensory and motor nerves; connects to skeletal muscles and skin.
    • Autonomic nervous system: Nerves to internal organs; regulates automatic functions.
Sympathetic vs Parasympathetic Nervous Systems
  • Sympathetic: Arouses body for threat/stress (fight or flight); increases heart rate, inhibits digestion.
  • Parasympathetic: Calms body after threat (rest and digest); slows heart rate, stimulates digestion.
Neurons and Glial Cells (Glia)
  • Neurons: Primary information-processing cells; approx. 10^{11} in the brain; communicate via electrochemical signaling and neurotransmitters.
  • Glial cells (glia): Support cells providing nutrition, structural support, debris clearance; can repopulate.
    • Glial-to-neuron ratio in cortex is about 4:1.
    • Mirror neurons: Involved in imitation and social perception.
Neuron Structure: Core Components
  • Soma (cell body): Contains nucleus, sustains cell life.
  • Dendrites: Receive information from other neurons.
  • Axon: Carries information away from cell body.
  • Myelin sheath: Fatty layer insulating axon, speeds electrical signals.
  • Terminal buttons: End of axon, release signals into synapse.
  • Synapse: Tiny gap between neurons where communication occurs.
  • Synaptic vesicles: Store neurotransmitters in terminal buttons.
The Action Potential: Electrical Signaling Within Neurons
  • Membrane and ion distribution: Negatively charged ions inside, positively charged outside at rest (Cl⁻ inside; Na⁺, K⁺ outside).
  • Resting potential: Neuron at rest, charge across membrane is -60 ext{ mV} ext{ to } -75 ext{ mV}.
  • Semi-permeable membrane: Axon membrane with ion channels regulating ion flow.
  • Threshold of excitation: Critical level (-55 ext{ mV}) to trigger an action potential.
  • Action potential sequence: If threshold reached, positive ions (Na⁺) flood in, depolarizing neuron to +35 ext{ mV}; propagates down axon.
  • All-or-none principle: Action potential is either fully generated or not at all.
  • Return to rest: Ionic balance restored after action potential passes.
From Electrical to Chemical Signaling: Neurotransmitters and the Synapse
  • Electrical signal at terminal buttons converts to chemical signal.
  • Neurotransmitters: Chemical messengers released into synapse; bind to receptors on next neuron's dendrites.
  • Process: electrical impulse (action potential)
    \to chemical signaling (neurotransmitters)
    \to electrical signal in next neuron.
Key Terms and Formulas to Remember
  • Resting potential range: -60 ext{ mV} ext{ to } -75 ext{ mV}
  • Threshold of excitation: -55 ext{ mV}
  • Peak of action potential: +35 ext{ mV}
  • Neuron count: approx. 10^{11}
  • Glial-to-neuron ratio (cortex): 4:1
  • Ions: Cl⁻ (negative); Na⁺, K⁺ (positive)
Summary of the Signal Pathway (Conceptual Flow)
  • Dendrites receive input
    \to Soma
    \to Axon
    \to Terminal buttons release neurotransmitters into synapse
    \to Next neuron’s dendrites receive signal.
End-of-Lecture Probing Points
  • Distinguish afferent vs efferent nerves.
  • Describe four nervous system properties.
  • Explain myelin sheath purpose and consequences of poor myelination.
  • Define resting potential, threshold, and action potential (mV, ion movement).
  • Outline all-or-none principle.
  • Describe synapses and synaptic vesicles role.
  • Recall major brain-behavior connections.