The Role of Biology in Psychology

CHAPTER 2: THE ROLE OF BIOLOGY IN PSYCHOLOGY

2.1 Overview of Chapter 2
Big Questions

  1. How does your nervous system work?

  2. How do the parts of your brain function?

  3. How does your brain communicate with your body?

  4. How do nature and nurture affect your brain?

2.1 Your Nervous System is the Basis of Your Mental Activity and Behavior
Definition of Nervous System

  • The Nervous System is defined as a network of billions of cells in the brain and the body, responsible for all aspects of what we feel, think, and do.

Three Basic Functions of the Nervous System

  1. Receive sensory input from the world through the five senses.

  2. Process the information in the brain by paying attention to it, perceiving it, and remembering it.

  3. Respond to the information by acting on it.

Components of the Nervous System

Central Nervous System (CNS)

  • The Central Nervous System consists of:

    • The Brain

    • The Spinal Cord

Peripheral Nervous System (PNS)

  • The Peripheral Nervous System connects the CNS to the skin, muscles, organs, and glands.

Nervous System Figure Explanation

  • Figure 2.1 illustrates the structure of the nervous system:

    • Somatic Nervous System: Controls voluntary movements by sending signals between the brain and spinal cord to the muscles, joints, and skin.

    • Autonomic Nervous System: Controls involuntary functions among glands and internal organs.

    • Sympathetic Nervous System: Mobilizes the body for action.

    • Parasympathetic Nervous System: Conserves energy.

2.1 The Role of Neuronsff
Definition of Neurons

  • Neurons are the basic units of the nervous system that:

    • Receive, integrate, and transmit information.

    • Operate through electrical impulses.

    • Connect with other neurons through chemical signals.

    • Communicate selectively with other neurons and form neural networks.

Structure of Neurons

  1. Dendrites: Have receptors that detect information from other neurons.

  2. Cell Body: Integrates information from all of a neuron’s dendrites.

  3. Axon: Long, narrow outgrowth of a neuron that transmits information to other neurons.

  4. Terminal Buttons: The end of the axon that releases chemical signals from the neuron into the synapse.

  5. Synapse: The gap that neurotransmitters travel across to reach the dendrites of the next neuron.

  6. Myelin Sheath: A fatty material that covers and insulates some axons to allow faster movement of electrical impulses along the axon.

2.2 Neurons Communicate with Each Other
Action Potential

  • An Action Potential is defined as a neural impulse that travels along the axon and causes the release of neurotransmitters into the synapse.

Phases of Neuronal Communication

  • Neurons communicate in three phases:

    1. Transmission Phase: The action potential travels down the axon.

    2. Reception Phase: Neurotransmitters bind to receptors on the post-synaptic neuron.

    3. Integration Phase: The post-synaptic neuron processes the received signals.

Neurotransmitters in the Synapse

  • Neurons do not touch; they communicate through neurotransmitters.

  • Receptors are specialized sites that specifically respond to certain neurotransmitters.

2.4 Our Understanding of How the Brain Works Has Improved Over Time
Modern Brain Research Techniques

  1. Electroencephalography (EEG): Used to measure electrical activity in the brain, revealing different behavioral states.

  2. Functional Magnetic Resonance Imaging (fMRI): Measures changes in the blood’s oxygen level to indicate brain activity.

  3. Transcranial Magnetic Stimulation (TMS): Disrupts activity in specific brain regions using a powerful magnetic field.

Brain Structure and Function
Hindbrain

  • Medulla: Responsible for breathing, heart rate, and other survival mechanisms.

  • Pons: Involved in sleep, arousal, and coordination of left-right body movements.

  • Cerebellum: Responsible for motor learning, coordination, and balance.

Midbrain

  • Substantia Nigra: Critical for the initiation of voluntary motor activity and the production of dopamine; its degradation is associated with Parkinson’s disease.

Forebrain (Subcortical Structures)

  1. Thalamus: Acts as the sensory gateway for all senses except smell.

  2. Hypothalamus: Regulates body functions and motivates behaviors related to hunger, thirst, and sex.

  3. Hippocampus: Essential for the formation of new memories.

  4. Amygdala: Associates emotions with experiences.

Forebrain (Cortical Structures)

  1. Occipital Lobes: Responsible for vision.

  2. Parietal Lobes: Involved in touch and spatial information processing.

  3. Temporal Lobes: Responsible for hearing and memory functions.

  4. Frontal Lobes: Involved in planning, movement, and complex thought processes.

2.8 The Hemispheres Work Together with Some Specialization
Split Brain

  • A Split Brain condition occurs when the corpus callosum is surgically severed, preventing direct communication between the two hemispheres.

Functions of the Hemispheres

Right Hemisphere

  • Responsible for spatial relationships.

  • Controls movements of the left side of the body.

  • Processes images from the left visual field.

Left Hemisphere

  • Responsible for logical thoughts and language production.

  • Controls movements of the right side of the body.

  • Processes images from the right visual field.

Left Brain/Right Brain Myth

  • Myth: The left-brain thinkers are considered more rational and analytical, while right-brain thinkers are seen as more creative and holistic.

  • Scientific Evidence: Both hemispheres are specialized for certain functions but are also capable of carrying out most cognitive processes, often in varied ways.