Chapter_3_-_Biopsychology

3.1 Human Genetics

Learning Objectives

  • Explain basic principles of evolution by natural selection.

  • Describe differences between genotype and phenotype.

  • Discuss gene-environment interactions critical for the expression of physical and psychological characteristics.

Key Concepts

  • Human Genetics Importance: Researchers study genetics to understand biological factors contributing to certain behaviors.

  • Genetic Variation: Despite similar biological mechanisms, individual expression varies widely in behaviors, thoughts, and reactions.

Example - Sickle Cell Anemia

  • Definition: A genetic condition where red blood cells become crescent-shaped, impacting their function.

  • Impact: Sickle-shaped cells can obstruct blood vessels, leading to serious health issues.

  • Example of Genetic Advantage: Carriers of one sickle cell allele have some immunity to malaria, illustrating how genetic traits can vary in effectiveness based on environmental context.

Natural Selection Case Study

  • Sickle cell gene remains common in Africa despite its harmful effects because it provides malaria protection.

  • Darwin's Theory of Evolution: Organisms best suited for their environment survive and reproduce.

Perspectives on Genetics and Behavior

1. Evolutionary Psychology

  • Focuses on how behavior and cognitive processes have evolved over time.

  • Investigates adaptive behaviors such as fear responses and mating preferences.

2. Behavioral Genetics

  • Examines individual differences and how they arise from genetic and environmental interactions.

  • Utilizes twin studies and adoption studies to assess the contributions of genetics and environment to behavior.

Genetic Variation

  • Begins at fertilization, combining genetic material from egg and sperm.

  • Chromosomes contain DNA and genes controlling traits (e.g., eye color).

Genotype vs. Phenotype

  • Genotype: Genetic makeup.

  • Phenotype: Observable characteristics influenced by genotype and environment.

  • Alleles: Variations of genes that determine traits. Dominant and recessive allele interactions define physical expressions.

Punnett Squares

  • Used to predict inheritance patterns of traits and probabilities of offspring characteristics.

Polygenic Traits

  • Most human traits (e.g., height, weight, skin color) are polygenic, influenced by multiple genes.

Gene Mutations

  • Can be harmful or beneficial, driving evolution through variability and adaptation in changing environments.

Race and Genetics

  • Race as a genetic parameter has been deemed less significant; more genetic diversity exists within racial categories than between them.

  • Focus should be on ancestry to understand genetic diversity better.

Gene-Environment Interactions

  • Range of Reaction: Genes set potential limits; environment influences achievement within those limits.

  • Example: A stimulating environment improves potential outcomes for individuals with high intellectual predispositions.

Epigenetics

  • Explores how environmental factors can influence gene expression, highlighting that genotype can lead to varied phenotypes depending on context.

  • Example: Identical twins with the same DNA may have different health outcomes based on environmental influences.

Behavioral Implications

  • Genetic factors can link to traits and disorders, including schizophrenia and depression.

  • Both genetic predispositions and environmental stressors contribute to the development of disorders.

3.2 Cells of the Nervous System

Learning Objectives

  • Identify basic parts of a neuron.

  • Describe neuron communication.

  • Explain the roles of drugs in neurotransmitter systems.

Neurons and Glial Cells

  • Neurons: Main cells for processing information in the nervous system, interconnected for communication.

  • Glial Cells: Support neurons by providing nutrition, insulation, and structural support.

Neuron Structure

  • Parts of Neurons:

    • Soma: Cell body, containing the nucleus.

    • Dendrites: Branches that receive signals.

    • Axon: Long extension transmitting signals to other neurons.

    • Myelin Sheath: Insulation that speeds up signal transmission.

Neuronal Communication

  • Action Potential: Electrical signal that travels along the axon.

  • Synaptic Transmission: Neurotransmitters released from terminal buttons into synaptic cleft, interacting with receptors on adjacent neurons.

  • All-or-None Principle: Action potential occurs fully or not at all; it is propagated without reduction in strength.

Neurotransmitters and Drugs

  • Types of Neurotransmitters: Various neurotransmitters affect specific behaviors and physiological functions.

  • Psychotropic Medications: Correct imbalances by acting as agonists (mimicking) or antagonists (blocking) neurotransmitter receptors.

  • Reuptake Inhibitors: Prevent neurotransmitters from being reabsorbed, keeping them active longer (e.g. SSRIs for depression).

3.3 Parts of the Nervous System

Learning Objectives

  • Distinguish between the central and peripheral nervous systems.

  • Explain somatic vs. autonomic nervous systems.

Central vs. Peripheral Nervous System

  • Central Nervous System (CNS): Comprises the brain and spinal cord.

  • Peripheral Nervous System (PNS): Extends beyond the CNS, connects the body to the environment.

Somatic Nervous System

  • Controls voluntary movements through motor (efferent) and sensory (afferent) neurons.

Autonomic Nervous System

  • Regulates involuntary body functions; divided into sympathetic (stress response) and parasympathetic (restoration) systems.

3.4 The Brain and Spinal Cord

Learning Objectives

  • Describe spinal cord functions and brain structures.

Spinal Cord

  • Acts as a relay for signals and a center for reflexes.

Brain Structures

  • Distinct regions carry out different functions; each hemisphere is divided into four lobes: frontal, parietal, temporal, and occipital

  • Frontal Lobe: Involved in reasoning, motor control.

  • Parietal Lobe: Processes sensory information.

  • Temporal Lobe: Associated with hearing and emotional responses.

  • Occipital Lobe: Handles visual processing.

Hemispheric Functionality

  • Left side controls right body functions; right side controls left body functions; some functions are lateralized.

Imaging Techniques

  • Various imaging techniques (CT, PET, MRI, fMRI, EEG) provide insights into brain functions and structures.

3.5 The Endocrine System

Learning Objectives

  • Identify major glands and their functions.

Major Endocrine Glands

  • Pituitary Gland: Master gland; regulates other glands.

  • Thyroid: Regulates growth and metabolism.

  • Adrenal Glands: Produce stress response hormones.

  • Pancreas: Controls blood sugar levels.

  • Gonads: Secrete sexual hormones influencing reproduction.

Hormonal Functions

  • Hormones regulate numerous body functions, with effects that tend to be slower and longer-lasting than neurotransmitter effects.