AP Psychology - Unit 1 Review: Biological Basis

Nature: Genetic inheritance from parents, including physical and psychological traits.
Nurture: Environmental influences and experiences shaping us from infancy through adulthood.
Nature provides physical traits (e.g., hair color, height), while nurture shapes behaviors, skills, and personality.
It's an interaction, not a debate: Nature and nurture constantly interact to shape behaviors.
Charles Darwin's theory of evolution by natural selection: traits enhancing survival and reproduction are passed on.
- Explains persistence of certain behaviors through human history.
Evolutionary psychology offers insights but has been misused (e.g., eugenics).
- Eugenics: Early 20th-century movement to improve human population through selective breeding, leading to enforced sterilizations and discrimination.
- Ethical integrity is crucial when applying these theories (science practice two).
Research strategies to isolate gene and environment influence:
- Twin studies: Studying identical twins to see how different environments affect behavior.
- Adoption studies: Separating influences of home environment from genetic factors by studying children raised apart from biological parents.
- Family studies: Examining traits across generations to identify genetic vs. environmental influence.

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: Relay station organizing and sending neural messages to the body.
Peripheral Nervous System (PNS):
- Includes nerve endings branching from the brain and spinal cord.
- Transmits information to the CNS and carries orders from the CNS.
- Two Subdivisions:
  - Somatic Nervous System: Processes voluntary movement and transmits sensory information to the CNS.
  - Autonomic Nervous System: Controls involuntary functions like heart rate, digestion, and breathing.
    - Two further Subdivisions:
      - Sympathetic Nervous System: Activates fight or flight response during perceived threats.
      - Parasympathetic Nervous System: Returns the body to normal functioning after the threat is gone.

Neurons are the primary communication cells.
- Powered by electricity, approximately 86 billion neurons send neural messages.
Glial cells support the neurons by:
- Supporting, protecting, and nourishing neurons.
- Cleaning up waste in the nervous system.
- Outnumber neurons 10 to 1.
Anatomy of a neuron:
- Nucleus: Contains the neuron's genetic information (brain of the cell).
- Cell body (soma): Provides structural support and processes nutrients.
- Dendrites: Receive incoming 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 information from senses and send it to the brain.
- Motor neurons: Carry out motor actions from the brain and release hormones.
- Interneurons: Direct messages throughout the nervous system.
Reflex Arc
- Explains how three neurons work together
- Example: Doug touching a hot stove
  - Sensory neurons detect extreme heat and send this to the spinal cord.
  - Interneurons process this signal as pain and send a message to motor neurons.
  - Motor neurons cause Doug to reflexively move his hand from the stove stimulus

Action potential: An electrical charge collected by dendrites and cell body, sent down the axon when a neuron receives stimulation.
Stimulus threshold: The minimum stimulation needed for an action potential to occur.
All-or-nothing principle: A neuron either receives enough stimulation for an action potential or it doesn't.
Refractory period: The neuron recharges and cannot send a message during this time.
Resting potential: The neuron is recharged and ready to send the next message.
Neurotransmission:
- The electrical charge from the action potential causes the axon to release chemical messengers called neurotransmitters.
- Reuptake: The released chemicals are reabsorbed, allowing them to be reused.
Autoimmune disorders affecting neural transmission:
- Multiple sclerosis and myasthenia gravis lead to muscle weakness, fatigue, and loss of mobility.

Chemical messengers controlling aspects of life.
Excitatory messages increase brain activity by triggering action potentials.
Inhibitory messages slow down brain activity, preventing further action potentials.
Key Neurotransmitters
- Dopamine: Pleasure & reward; influences mood, attention, and movement; linked to addiction.
  - Plays a role in humor, especially surprise or expectation violations. The brain enjoys anticipating something unexpected or out of the ordinary.
- Serotonin: Regulates mood, appetite, and sleep; lack of serotonin is linked to depression.
- Norepinephrine: Affects alertness and arousal; similar to adrenaline and abundant.
- Glutamate: Excitatory, critical for brain functions, regulating cognitive functions, learning, and memory.
- GABA (gamma-aminobutyric acid): Inhibitory, slows down brain activity by reducing action potentials.
- Endorphins: Reduce pain response, induce feelings of pleasure and happiness.
- Substance P (