AP Psychology Biological Bases of Behavior Notes

AP Psychology: Biological Bases of Behavior Notes

Key Takeaways: Biological Bases for Behavior

  1. All human (and animal) behavior is a product of biological structures and processes, highly organized on multiple interconnected levels. Understanding these biological precursors of behavior can lead to treatments for psychological disorders, such as drugs that influence neurotransmitter function.
  2. The nervous system is highly specialized and hierarchical in its structure, but neuroplasticity gives the brain some flexibility to adapt its structure and function. 
  3. Though interconnected with and regulated by the nervous system, the endocrine system produces effects on behavior in a distinct way: endocrine glands secrete hormones into the bloodstream, allowing hormones to reach and interact directly with target organs. 
  4. Biopsychological researchers use a variety of imaging technologies to view the structure and function of the brain, along with specialized research strategies that allow them to learn more about the brain’s organization and the origin of psychological traits. 
  5. While many behaviors are learned as a result of experience within a particular environment, the very capacity to learn such behaviors has a genetic basis, and such capacities only persist because they contribute to the fitness of organisms. 
  6. Since the late nineteenth century, psychologists have investigated consciousness, including the awareness of one’s self and environment, the ways consciousness can be altered, and the various levels and states of consciousness. 
  7. Sleep cycles through multiple stages that vary in levels of neural activity, muscle control, biological functions, and dreaming; sleep disorders cause disruptions to these processes. 
  8. Psychoactive drugs, including depressants, narcotics, stimulants, and hallucinogens, affect brain chemistry to alter the perceptions and behavior of users; some psychoactive drugs are used medicinally and/or recreationally, and some have a high potential for abuse.

Biological Bases for Behavior Key Terms


  • Neurons: The basic functional units of the nervous system; cells which contain specialized structures to communicate signals.
  • Soma/cell body: The part of a neuron that contains its nucleus and other standard cellular structures.
  • Dendrites: The multiple thin, treelike fibers that branch off from a neuron’s soma and contain receptors to accept incoming signals from other neurons.
  • Axon: A long, tubular structure in a neuron that transmits action potentials.
  • Myelin sheath: A fatty substance that coats an axon, insulating it and enhancing its ability to transmit action potentials.
  • Terminal buttons: The branching structures at the ends of axons that release neurotransmitters.
  • Synapse: The small gap between the axon of a presynaptic neuron and the dendrites of a postsynaptic neuron.
  • Action potential: The electrical impulse sent along an axon when the dendrites of a neuron are sufficiently excited.
  • Neurotransmitter: A specialized chemical messenger which sends signals between neurons.
  • Excitatory: Describes a neurotransmitter that causes a postsynaptic neuron to propagate more action potentials.
  • Inhibitory: Describes a neurotransmitter that causes a postsynaptic neuron to propagate fewer action potentials.
  • Acetylcholine: A neurotransmitter involved in learning, memory, and muscle contraction.
  • Dopamine: A neurotransmitter involved in mood, movement, attention, and learning.
  • Serotonin: A neurotransmitter that regulates sleep, mood, appetite, and body temperature.
  • Gamma amino butyric acid (GABA): The primary inhibitory neurotransmitter in the nervous system.
  • Norepinephrine: A neurotransmitter important in controlling alertness, wakefulness, mood, and attention.
  • Glutamate: The main excitatory neurotransmitter in the central nervous system; important for learning and memory.
  • Agonists: Drugs that mimic a particular neurotransmitter, activating the same receptors that it does.
  • Antagonists: Drugs that block a particular neurotransmitter from activating its receptors.
  • Re-uptake inhibitors: Drugs that prevent a neurotransmitter from being reabsorbed by presynaptic axons, causing greater activation of postsynaptic receptors.
  • Selective serotonin re-uptake inhibitors (SSRIs): Drugs that prevent the reabsorption of serotonin, leading to greater activation of serotonin receptors.

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