AP Psychology - Unit 1: Biological Basis Review

Introduction

  • The biological basis of psychology explores how biological structures influence behavior.
  • This unit covers heredity, the nervous system, neurons, brain structure, consciousness, and the senses.

Nature vs. Nurture

  • Nature: Genetic inheritance influencing physical and psychological traits.
  • Nurture: Environmental influences shaping development from infancy to adulthood.
  • Nature provides physical traits (e.g., hair color, height), while nurture shapes behaviors, skills, and personality.
  • The interaction between nature and nurture shapes behavior.
  • Charles Darwin's Theory of Evolution: Traits enhancing survival are passed on. Explains the persistence of certain behaviors through history.
  • Eugenics: A misused application of evolutionary psychology aimed at improving the human population through selective breeding. It led to ethical issues and discrimination.
  • Ethical integrity is crucial when applying psychological theories.
  • Research strategies help isolate genetic and environmental influences:
    • Twin Studies: Studying identical twins to identify differences in behavior influenced by the environment.
    • Adoption Studies: Studying children raised apart from biological parents to separate home environment influences from genetic factors.
    • Family Studies: Examining traits across generations to see how traits might be influenced by genetics versus environment.

The Nervous System

  • The nervous system consists of the central nervous system (CNS) and the peripheral nervous system (PNS).
  • Central Nervous System (CNS):
    • Brain: Command center processing sensory data and coordinating responses.
    • Spinal Cord: Relays neural messages to the body.
  • Peripheral Nervous System (PNS):
    • Includes nerve endings branching from the brain and spinal cord.
    • It transmits information to the CNS and carries orders from the CNS.
    • Divided into the somatic and autonomic nervous systems.
  • Somatic Nervous System: Controls voluntary movement and sensory information transmission to the CNS (e.g., waving goodbye).
  • Autonomic Nervous System: Manages involuntary functions (e.g., heart rate, digestion, breathing).
    • Sympathetic Nervous System: Activates the fight or flight response during perceived threats.
    • Parasympathetic Nervous System: Returns the body to normal functioning after the threat is gone.

Neurons and Glial Cells

  • Neurons: The primary communication cells of the nervous system.
    • Powered by electricity, approximately 86 billion neurons send neural messages.
  • Glial Cells: Support, protect, and nourish neurons and clean up waste.
    • Outnumber neurons 10 to 1.
  • Neuron Anatomy:
    • Nucleus: Contains genetic information.
    • Cell Body (Soma): Provides structural support and processes nutrients.
    • Dendrites: Receive messages from other neurons.
    • Axon: Sends information to the next neuron.
    • Myelin Sheath: Glial cells wrapping around the axon, speeding up neural message travel.
  • Types of Neurons:
    • Sensory Neurons: Collect sensory information and send it to the brain.
    • Motor Neurons: Carry out motor actions sent from the brain and release hormones.
    • Interneurons: Direct messages throughout the nervous system in the CNS and outnumber sensory and motor neurons.
  • Reflex Arc: Demonstrates how neurons work together.
    • Sensory neurons detect a stimulus (e.g., touching a hot stove).
    • Interneurons in the spinal cord process the signal and send a message directly to motor neurons.
    • Motor neurons cause a reflexive action (e.g., jerking hand away) without brain input.

Neural Communication

  • Action Potential: An electrical charge is triggered when a neuron receives enough stimulation.
  • Stimulus Threshold: The minimum stimulation required for an action potential.
  • All-or-Nothing Principle: A neuron either fires an action potential or does not.
  • Refractory Period: The neuron quickly recharges and cannot send a message during this time.
  • Resting Potential: The neuron is recharged and ready to send the next message.
  • When an action potential reaches the axon terminal, the neuron releases chemicals to transmit the message to the next neuron.
  • Reuptake: Chemicals are reabsorbed, reused, and conserving body resources.
  • Issues with neural transmission can lead to disorders like multiple sclerosis and myasthenia gravis.
    • These autoimmune disorders cause muscle weakness, fatigue, and loss of mobility, due to white blood cells attacking the body’s neurons.

Neurotransmitters

  • Chemical messengers controlling various aspects of life.
  • Excitatory Messages: Increase brain activity.
  • Inhibitory Messages: Slow down brain activity.
  • Examples:
    • Dopamine:
      • Important for pleasure and reward systems.
      • Influences mood, attention, and movement.
      • Linked to addiction.
      • Activated when there is an expectation of hearing something inappropriate or funny.
    • Serotonin:
      • Regulates mood, appetite, and sleep.
      • Lack of serotonin is associated with depression.
    • Norepinephrine:
      • Affects alertness and arousal.
      • It is Similar to adrenaline.
    • Glutamate:
      • Critical for normal brain functions.
      • Regulates cognitive functions like learning and memory.
    • GABA (Gamma-Aminobutyric Acid):
      • Major inhibitory neurotransmitter.
      • Slows down brain activity.
    • Endorphins:
      • Natural painkillers.
      • Reduce pain response and induce pleasure and happiness.
    • Substance P:
      • Regulates pain.
    • Acetylcholine:
      • Stimulates muscle contractions.
      • Plays a role in attention and memory.
  • Neural Transmission:
    • Presynaptic Neuron: Sends the message.
    • Postsynaptic Neuron: Receives the message.
    • Synapse: Fluid-filled gap between neurons.
    • Neurotransmitters are stored in synaptic vesicles.
    • Receptor sites on dendrites of the postsynaptic neuron receive neurotransmitters.
    • Matching neurotransmitters bind to receptors, exciting or inhibiting the neuron.
    • Reuptake: the neurotransmitters process of being reabsorbed back into synaptic vesicles once neural communication is complete.

Endocrine System

  • Hormones (chemical messengers) influence behavior.
  • Controlled by the hypothalamus and pituitary gland.
  • Examples:
    • Adrenaline:
      • Roles in the fight or flight response.
      • Prepares the body for action by increasing heart rate, blood pressure, and energy supplies.
    • Leptin:
      • Released by fat cells.
      • Regulates energy balance by suppressing appetite.
    • Ghrelin:
      • Released by the stomach.
      • Stimulates appetite.
    • Melatonin:
      • Released by the pineal gland.
      • Prepares the body for sleep.
    • Oxytocin:
      • Plays a role in social bonding and reproduction.
      • Released by physical touch and believed to reduce stress.

Psychoactive Drugs

  • Substances altering brain function, causing changes in perception, mood, consciousness, and behavior.
  • Influence neurotransmitter activity:
    • Agonists: Mimic natural neurotransmitters.
    • Antagonists: Stop chemicals from binding to a receptor site.
    • Reuptake Inhibitors: Block reuptake, increasing neurotransmitter levels in the brain. SSRIs block serotonin reuptake to combat depression.
  • Examples:
    • Stimulants: Increase brain activity (e.g., caffeine, cocaine).
    • Depressants: Slow down central nervous system activity (e.g., alcohol).
    • Hallucinogens: Alter perceptions, moods, and thoughts (e.g., marijuana).
    • Opioids: Provide pain relief and euphoric effects (e.g., heroin). Increase dopamine levels, leading to addiction.
  • Addiction:
    • Chronic condition characterized by drug seeking and use despite harmful consequences.
    • Impacts physical health, relationships, and work life.
    • Tolerance: The brain adapts and needs more of the substance to achieve the same effects.
    • Withdrawal Symptoms: Physical or psychological symptoms after stopping substance use.

Brain Structures and Functions

  • Brain Stem:
    • Medulla: Controls automatic functions like breathing, heart rate, and blood pressure.
    • Cerebellum: Coordinates motor control, posture, balance, and speech.
    • Reticular Activating System (RAS): Regulates the sleep-wake cycle and attention.
  • Limbic System:
    • Emotional center of the brain.
    • Reward Center: Calculates and responds to rewards, influencing decision-making and addictive behaviors.
    • Thalamus: Sensory relay station (except for smell).
    • Hypothalamus: Regulates hunger, thirst, temperature, and emotional responses; controls the pituitary gland. It controls the four F’s of survival (fighting, fleeing, feeding, mating).
    • Pituitary Gland: Master gland of the endocrine system, influencing other glands in the body and roles in regulating growth, metabolism, and reproduction.
    • Hippocampus: Creates new memories.
    • Amygdala: Processes emotional aspects of memory and emotional responses, especially fear and pleasure.
  • Cerebral Cortex:
    • Deals with complex thoughts and functions.
    • Divided into left and right hemispheres connected by the corpus callosum.
    • Occipital Lobe: Visual processing.
    • Temporal Lobe: Auditory information and sounds.
    • Parietal Lobe: Processes sensory signals, spatial orientation, and navigation.
    • Frontal Lobe: Decision-making, problem-solving, planning, controlling speech and motor movements.
  • Specialized Areas:
    • Prefrontal Cortex: Decision-making, planning, and social behavior; matures in mid-20s.
    • Motor Cortex: Plans and executes voluntary movements.
    • Somatosensory Cortex: Processes sensory information from the body.
    • Broca's Area: Production of speech, located in the left hemisphere of the frontal lobe.
    • Wernicke's Area: Language comprehension, located in the left hemisphere of the temporal lobe.
  • Aphasia: Damage to Broca's or Wernicke's area leading to speech production or comprehension issues.
  • Split-Brain Procedure: Cutting the corpus callosum to reduce epileptic seizures. It revealed distinct specializations of each hemisphere.
  • Contralateral Hemispheric Organization: The left hemisphere controls the right side of the body, and vice versa.
  • Brain Plasticity:
    • Functional Plasticity: The brain shifts functions from a damaged area to a non-damaged area.
    • Structural Plasticity: The brain changes its physical structure through learning and experience.

Brain Scans

  • fMRI (Functional Magnetic Resonance Imaging): Measures brain activity by detecting changes in blood flow; highlights areas consuming more oxygen during mental processes.
  • EEG (Electroencephalogram): Measures the brain’s electrical activity using electrodes on the scalp; doesn’t offer visual image but analyzes the timing of responses.
  • Lesioning Studies: Intentionally damaging an area of the brain (usually in animals) to observe the damage's effect on behavior.
  • Case Studies: Observing unique cases of individuals with brain damage due to accidents, strokes, or diseases to predict the function of damaged areas.

Consciousness

  • Awareness of mental processes and the external environment.
  • Levels range from wakefulness to sleep.
  • Circadian Rhythm: Internal biological clock on a 24-hour cycle regulating the sleep-wake cycle. Jet lag, night shifts, and phone usage disrupts this rhythm.
  • Sleep Stages:
    • NREM (Non-Rapid Eye Movement) Sleep:
      • Stage 1: Light sleep, easily awakened, slow rolling eye movements, possible hypnagogic hallucinations.
      • Stage 2: Brain activity slows, marked by sleep spindles and K-complexes, waking up becomes more difficult.
      • Stage 3: Deepest sleep, slow delta brain waves, rejuvenates the body, strengthens the immune system, and consolidates memories.
    • REM (Rapid Eye Movement) Sleep:
      • Increased brain activity similar to being awake.
      • Sleep paralysis occurs.
      • Crucial for processing emotions, consolidating memories, and learning.
      • REM Rebound: The brain increases the duration of REM sleep after sleep deprivation.
  • Theories of Sleep:
    • Restorative Theory: Sleep is essential for physical repair and recovery.
    • Adaptive Theory: Sleep evolved to enhance survival by conserving energy and reducing the risk of danger.
  • Theories of Dreams:
    • Activation Synthesis Theory: Dreams result from the brain's attempt to make sense of random neural activity during REM sleep.
    • Memory Consolidation Theory: Dreams play a critical role in processing and consolidating memories.
  • Sleep Deprivation:
    • Physiological effects include a weakened immune response and increased heart rate.
    • Psychological effects include impaired memory, reduced concentration, increased irritability, and mood swings.
  • Sleep Disorders:
    • Insomnia: Difficulty falling or staying asleep; treatment includes therapy, improved sleep habits, and medication.
    • Narcolepsy: Extreme daytime sleepiness and sudden episodes of falling asleep; treatment includes stimulants and antidepressants.
    • REM Sleep Behavior Disorder: Acting out vivid dreams; treatment typically involves medication.
    • Sleep Apnea: Blocked airways interrupting breathing disrupts REM sleep; treatment involves lifestyle changes and devices like CPAP machines.
    • Somnambulism (Sleepwalking): Getting up and walking around during stage 3 NREM sleep; treatment focuses on safety measures and sometimes medication.

Senses

  • Sensation: Sensory organs collect information and send it to the brain for processing.
  • Transduction: Physical stimuli are converted into electrical signals the brain can understand.
  • Sensory Thresholds:
    • Absolute Threshold: The minimum strength of a stimulus needed for detection 50% of the time.
    • Difference Threshold (Just Noticeable Difference - JND): The smallest detectable change in a stimulus