• Unit 2: Biological Bases of Behavior

    What makes you "you"? This question gets to the heart of one of the longest-running debates in psychology: the nurture versus nature dispute, which asks whether humans are a product of their environment or of their biological makeup. While it is unlikely that we will ever conclusively answer this question, research has provided us with some important insights that will help you understand the arguments on both sides of the debate.

    Early psychologists considered the brain a black box that controlled certain processes, although they did not know how to identify these processes or how the brain controlled them. This is no longer the case; now, scientists insist that the psychological mind and physiological body are fully integrated with one another. Today, knowledge of the biological origins of our psychological states is integral to the study of psychology.

    In this unit, we explore biopsychology, which includes the role of genes, the structure and functions of neurons, the parts of the nervous system, and the endocrine system. Finally, we examine the role and function of sleep and the use of substances that may alter our states of consciousness.

    Completing this unit should take you approximately 7 hours.

    • 2.1: Biopsychology and Human Genetics

      Although psychology is defined as a social science that studies behavior and mental processes, the fields of genetics and biology are also important for explaining these phenomena. Specifically, we draw on these fields to understand the biological causes of behaviors and the significance of brain functions and development.

    • 2.2: Cells of the Nervous System

      The human brain is comprised of billions of specialized cells called neurons. In this section, we learn about the basic parts of a neuron, how neurons communicate with each other, and how drugs can mimic or interfere with normal neuronal communication.

    • 2.3: Parts of the Nervous System

      Let's explore the two main divisions of the nervous system: the central nervous system and the peripheral nervous system. There are two main divisions within the peripheral nervous system: the somatic nervous system and the autonomic nervous system. Each of these divisions plays an important role in behavior and mental processes.

    • 2.4: The Brain and Spinal Cord

      The central nervous system consists of the brain – which consists of two hemispheres, each containing four lobes – and the spinal cord. The following resources explain the functions of the spinal cord, describe the two hemispheres and how they are connected, and the functions of the four lobes. The first text wraps up with a discussion of the technologies that allow for direct observation of the brain's structures and functions.

    • 2.5: The Endocrine System

      The endocrine system controls hormone levels, which regulate a number of behaviors such as metabolism, growth, sexual functions, sleep, reproduction, and mood. Here we explore the major glands of the endocrine system, the hormones they each use, and the hormone's role in bodily functions.

      Hormone secretion is often regulated through a negative feedback mechanism, which means that once a hormone is secreted, it will cause the hypothalamus and pituitary to shut down the production of signals necessary to secrete the hormone in the first place. Most oral contraceptives are made of small doses of estrogen or progesterone. Why is this an effective means of contraception?

    • 2.6: What Is Consciousness?

      We use the word consciousness in many different contexts. For example, we might say someone loses consciousness or displays self-consciousness. But what does the word consciousness really mean in these different statements? In this section, we explore the meaning of consciousness, how our circadian rhythms work, and what we mean by sleep debt.

    • 2.7: Sleep and Why We Sleep

      Sleep is a daily period of time and state of consciousness when the nervous system is relaxed and relatively inactive. Research has concluded that sleep is essential to our everyday health and functioning; even a short time without sleep can be linked to changes in our mood, awareness, and overall psychological functioning.

    • 2.8: Stages of Sleep

      Before the 1950s, we assumed we spent all of our time during a night's sleep in a consistent level of unconsciousness. Thanks to pioneering research, we now know that sleep is cyclical and consists of four stages of non-REM sleep plus REM sleep.

    • 2.9: Sleep Problems and Disorders

      Many people struggle with sleep, either temporarily or chronically. In this section, we examine the symptoms and risk factors for the typical sleep disorders of insomnia, parasomnias, sleep apnea, sudden infant death syndrome (SIDS), and narcolepsy. We explore some treatment options for each of these afflictions.

    • 2.10: Substance Use and Abuse

      Psychoactive drugs, such as prescription drugs and illegal substances, can induce altered states of consciousness. In this section, we explore the diagnostic criteria for substance use disorders, the neurotransmitter systems affected by different categories of psychoactive drugs, and how behaviors and mental processes are affected by different categories of drugs.

    • 2.11: Other States of Consciousness

      For those who are able to enter these states of mind, hypnosis and meditation can alter our state of consciousness. In this section, we define and differentiate hypnosis and meditation and explain their limitations and possibilities.

    • Unit 2 Assessment

      • Receive a grade