Psychology Lecture Notes

PSYCHOLOGY'S RESEARCH AND BIOPSYCHOLOGY

  • Biopsychology explores the biological mechanisms that underlie human behavior.
    • It studies various aspects including:
    • Genetics: Examining how inherited genes affect physiological and psychological traits.
    • Nervous System Structure & Function: Investigating how the structure of the nervous system interacts with its function.
    • Endocrine System Interaction: Studying the relationship between the nervous system and the endocrine system.

HUMAN GENETICS

  • Importance of Studying Human Genetics:
    • Understand biological bases of different behaviors, thoughts, and reactions in humans.
    • Questions addressed:
    • Why do individuals with the same disease exhibit different outcomes?
    • Are there genetic components to psychological disorders, e.g., depression?
    • How are genetic diseases inherited through families?

THEORY OF EVOLUTION

  • Charles Darwin's Contribution:
    • Proposed the theory of evolution by natural selection in 1859 via On the Origin of Species.
    • Key Concept:
    • Better-adapted organisms survive and reproduce, whereas poorly adapted organisms die off.
    • Characteristics impacting survival:
    • Protective behaviors against predators.
    • Behaviors that enhance access to food.
    • Behaviors that ensure offspring survival.
    • Notable Quote by Darwin:
      > "It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most adaptable to change."

EXAMPLE OF GENETIC DISEASE: SICKLE CELL ANEMIA

  • Sickle Cell Anemia Overview:
    • Genetic condition resulting in crescent-shaped red blood cells that can lead to blood flow blockages.
    • Causes premature death in many individuals, yet it remains prevalent among individuals of African descent.
    • Carriers of one sickle cell gene are immune to malaria, showcasing a case where a detrimental gene offers an environmental advantage.

GENETIC VARIATION

  • Defined as the genetic differences among individuals contributing to species adaptation.
  • Begins at fertilization of an egg and sperm, each containing 23 chromosomes, resulting in a zygote with 46 total chromosomes.
  • Chromosome Definition: Long strands of DNA containing genetic information.
  • DNA Basics:
    • Deoxyribonucleic Acid (DNA): Helix-shaped molecular structure made of nucleotide base pairs.
    • Gene: A sequence of DNA that influences physical characteristics (traits).
    • Alleles are different versions of a gene.

GENOTYPE VS PHENOTYPE

  • Genotype: Refers to the genetic makeup of an individual inherited from parents.
  • Phenotype: Observable characteristics of an individual, e.g., hair color, height, etc.

DOMINANT AND RECESSIVE ALLELES

  • Most inheritable traits are influenced by multiple genes (polygenic traits) but can also be determined by single genes.
  • Alleles can be classified as:
    • Dominant Allele: Expressed phenotype regardless of the second allele (example: A).
    • Recessive Allele: Expressed phenotype only when homozygous (aa).
  • Definitions:
    • Heterozygous: Two different alleles (Aa).
    • Homozygous: Two identical alleles (AA or aa).

PUNNETT SQUARES

  • A tool used to predict potential genetic combinations in offspring.
  • Example:
    • For a trait like cleft chin, dominance is indicated with uppercase (B) for cleft and lowercase (b) for smooth chin.
    • Individuals heterozygous for cleft chin (Bb) present cleft chins while only bb individuals show smooth chins.

RECESSIVE GENE DISORDERS

  • Example of PKU:
    • Punnett Square Analysis: When two heterozygous individuals (Np) mate, their children have a 25% chance of expressing PKU, a disorder caused by a recessive gene.
    • Mutations: Sudden changes in genes, which may be harmful or beneficial.

GENE-ENVIRONMENT INTERACTIONS

  • Nature and Nurture: Highlights the complex interplay between genetic predispositions and environmental factors.
  • Concepts:
    • Range of Reaction: Genes define limits within which an individual can operate.
    • Genetic Environmental Correlation: Suggests that our genes influence our environments while also being shaped by them.
    • Epigenetics: Study of gene expression changes due to environmental factors without altering the DNA sequence itself.

NEURON STRUCTURE

  • A neuron’s function is influenced by its structure:
    • A semi-permeable membrane allows small or neutral molecules to pass, blocking larger or charged ones.
    • Dendrites: Receive signals from other neurons.
    • Axon: Transmits signals to other neurons.
    • Myelin Sheath: Fatty insulation around axons that enhances signal transmission speed.

SYNAPSE AND NEUROTRANSMITTERS

  • Synapse: Space between neurons where neurotransmitters are released at terminal buttons, affecting dendrites of neighboring neurons.
  • Neurotransmitters: Chemical messengers facilitating communication across synapses.
    • Examples include:
    • Acetylcholine: Muscle movement and memory.
    • Dopamine: Involved in mood, sleep, and learning.
    • Serotonin: Regulates mood and sleep.

ACTION POTENTIAL

  • **Action Potential Process: **
    1. Binding of neurotransmitters causes postsynaptic changes in membrane potential (depolarization and hyperpolarization).
    2. If the excitation threshold is reached, sodium channels open allowing rapid influx of Na+ ions.
    • Principal Characteristics of Action Potentials:
    • Act on an all-or-none basis; they either occur fully or not at all.

THE NERVOUS SYSTEM

  • Two Main Parts:
    • Central Nervous System (CNS): Includes the brain and spinal cord.
    • Peripheral Nervous System (PNS): Includes all sensory and motor neurons that connect the body to the CNS.

PARTS OF THE PERIPHERAL NERVOUS SYSTEM

  • Somatic Nervous System: Handles voluntary control and sensory information delivery.
  • Autonomic Nervous System: Regulates involuntary functions and is divided into:
    • Sympathetic Nervous System: Controls stress responses (fight or flight).
    • Parasympathetic Nervous System: Manages routine day-to-day bodily functions (rest and digest).

BRAIN ANATOMY

  • Brain Structure: Comprised of interconnected neurons and cells, divided into lobes that interact.
  • Spinal Cord Functions: Conducts messages and reflex responses independent from brain signal processing.

CEREBRAL CORTEX AND BRAIN LOBES

  • The cerebral cortex manages high-level mental functions such as reasoning and memory, divided into four lobes:
    • Frontal Lobe: Executive functions and motor control.
    • Parietal Lobe: Sensory processing.
    • Temporal Lobe: Involved in memory and language comprehension.
    • Occipital Lobe: Visual processing.

LIMBIC SYSTEM

  • Structures of the limbic system including the Amygdala, Hippocampus, and Hypothalamus handle emotions, memory, and homeostatic regulation.

MIDBRAIN FUNCTIONS

  • Reticular Formation: Regulates arousal and wake cycles.
  • Substantia Nigra and VTA: Regions producing dopamine, associated with movement control and reward system respectively.

HINDBRAIN FUNCTIONS

  • Includes:
    • Medulla: Controls autonomic processes.
    • Pons: Links brain to the spinal cord, involved in sleep regulation.
    • Cerebellum: Manages balance and motor functions.

BRAIN IMAGING TECHNIQUES

  • Various imaging techniques leverage radiation or magnetic fields to visualize and assess brain structure and function:
    • CT Scan: Uses X-rays to create an image, can detect tumors.
    • PET Scan: Uses radioactive tracers to visualize brain activity.
    • fMRI: Monitors metabolic changes in the brain.
    • EEG: Records electrical activity using scalp electrodes.

THE ENDOCRINE SYSTEM

  • **Major Components: **
    • Pituitary Gland: Master gland controlling hormone secretion.
    • Thyroid Gland: Regulates metabolism and growth.
    • Adrenal Gland: Manages the stress response.
    • Gonads: Produce sex hormones affecting sexual behavior and motivations.

NEUROTRANSMITTER FUNCTIONS AND BEHAVIORS

  • Key neurotransmitters and their effects on behavior:
    • Acetylcholine: Involved in muscle action and memory enhancement.
    • Dopamine: Influences mood regulation and pleasure.
    • Serotonin: Impacts both mood and sleep regulation.
    • GABA: Aims to decrease anxiety through brain function moderation.