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Unit 2 Neurobiology Study Notes

Neurons

  • Parts:
    • Axon: Transmits electrical signals away from the cell body.
    • Dendrite: Receives signals from other neurons.
    • Myelin sheath: Insulates axon, speeding up signal transmission.
    • Terminal buttons: Release neurotransmitters into the synapse.
    • Cell body/soma: Contains the nucleus and maintains the neuron's life functions.
    • Synapse: The junction/gap between two neurons where signals are passed.
  • Process of firing:
    • Action potential: A brief electrical impulse that travels down the axon, an all-or-nothing response.
    • Reuptake: Neurotransmitters are reabsorbed by the sending neuron after transmitting a signal.
    • Refractory period: A brief period immediately after firing during which a neuron cannot fire again.
    • Resting state: The neuron's stable, inactive potential, ready to fire.
    • Electrical charges: Involved in the creation and transmission of neuronal signals through ion movement.

Neurotransmitters

  • Key types and their primary functions:
    • Dopamine: Reward, pleasure, motivation, motor control.
    • Too much: Linked to schizophrenia, hallucinations, and addictive behaviors.
    • Too little: Associated with Parkinson's disease (muscle rigidity, tremors) and depression.
    • Serotonin: Mood regulation, sleep, appetite.
    • Too much: Can lead to Serotonin Syndrome (agitation, muscle rigidity, rapid heart rate).
    • Too little: Linked to depression, anxiety disorders, and obsessive-compulsive disorder (OCD).
    • Acetylcholine (AcH): Muscle contraction, learning, memory.
    • Too much: Can cause muscle spasms, paralysis, and respiratory distress.
    • Too little: Associated with Alzheimer's disease (memory impairment) and difficulties in muscle movement.
    • Endorphins: Natural pain relief, feelings of well-being.
    • Too much: May mask pain signals, potentially leading to injuries, or artificial euphoria.
    • Too little: Can increase pain sensitivity and contribute to feelings of dysphoria.
    • GABA (Gamma-aminobutyric acid): Major inhibitory neurotransmitter, calms brain activity.
    • Too much: Can lead to excessive sedation, slurred speech, and loss of consciousness.
    • Too little: Linked to anxiety, insomnia, seizures, and tremors.
    • Glutamate: Major excitatory neurotransmitter, involved in learning and memory.
    • Too much: Can cause excitotoxicity (neuronal damage), migraines, seizures, and neurodegenerative diseases.
    • Too little: Associated with fatigue, poor concentration, and exhaustion.
    • Norepinephrine: Alertness, arousal, attention, 'fight or flight' response.
    • Too much: Can cause anxiety, hypertension, heart palpitations, and stress-related disorders.
    • Too little: Linked to depression, low energy, fatigue, and difficulty concentrating.

Types of Neurons

  • Afferent Neurons (Sensory): Carry sensory information from the body to the brain.
  • Efferent Neurons (Motor): Transmit motor signals from the brain to muscles and glands.

Nervous System Division

  • Autonomic Nervous System (ANS): Controls involuntary body functions (e.g., heart rate, digestion).
  • Somatic Nervous System: Controls voluntary movements of skeletal muscles.
  • Sympathetic Nervous System: Prepares the body for stressful situations; 'fight or flight' response.
  • Parasympathetic Nervous System: Calms the body down after stress; 'rest and digest' functions.

Reflexes

  • Reflexes: Involuntary, automatic responses to stimuli, involving simple neural pathways.

Brain Imaging Techniques

  • Used to study brain structure, function, or both:
    • Lesions: Areas of brain tissue damage used to observe resulting functional deficits.
    • EEG (Electroencephalogram): Measures electrical activity in the brain, showing brain waves.
    • CAT (Computed Axial Tomography) scan: Uses X-rays to create detailed cross-sectional images of brain structure.
    • MRI (Magnetic Resonance Imaging): Uses strong magnets and radio waves to provide high-resolution images of brain structure.
    • PET (Positron Emission Tomography) scan: Shows brain activity by tracking the glucose consumption of brain cells.
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