C3 PSYCH

BIOPSYCHOLOGY

  • Definition: The biological mechanisms that underlie behavior.

    • Components:

    • Genetics: how genes affect behaviors.

    • Physiological traits: physical characteristics influenced by biology.

    • Psychological traits: emotional and cognitive characteristics influenced by biology.

    • Nervous System: biological framework that supports behavior.

      • Neurons: basic units of the nervous system.

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

      • Peripheral Nervous System (PNS): connects the CNS to the rest of the body.

    • Brain Structure: various regions with distinct functions.

    • Endocrine System: hormonal influence on behavior.

HUMAN GENETICS

  • Importance: Studying human genetics helps understand the biological basis of different human behaviors, thoughts, and reactions.

    • Key Questions in Research:

    • Why do two individuals with the same disease experience different outcomes?

    • Are there genetic components to psychological disorders like depression?

    • How are genetic diseases transmitted through family lines?

THEORY OF EVOLUTION

  • Definition: The principle that organisms better suited to their environment survive and reproduce, while those poorly suited die off.

    • Important Quote: "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." – Charles Darwin.

THEORY OF EVOLUTION: SICKLE CELL ANEMIA

  • Description: Sickle cell anemia is a genetic condition where red blood cells become crescent-shaped, affecting their function.

    • Implications:

    • While it often leads to early mortality, the condition remains common among those of African descent.

    • Carriers of one sickle cell gene exhibit immunity to malaria, thus providing evolutionary benefits in certain environments.

  • Key Question: Why do harmful genetic diseases remain prevalent despite causing early death?

GENETIC VARIATION

  • Definition: The genetic differences between individuals.

    • Process: Initiated when an egg, containing 23 chromosomes, is fertilized by a sperm, also containing 23 chromosomes.

    • Chromosome: A long strand of genetic information (DNA).

      • DNA (Deoxyribonucleic acid): A helix-shaped molecule consisting of nucleotide base pairs.

    • Gene: A sequence of DNA that partially controls physical characteristics (traits) such as eye color or hair color.

    • Alleles: Variations of a gene that manifest as different traits.

GENOTYPE VS PHENOTYPE

  • Genotype: The genetic makeup of an individual based on genetic material inherited from parents.

  • Phenotype: The observable characteristics of an individual, including traits like hair color, skin color, height, and build.

DOMINANT VS RECESSIVE ALLELES

  • Dominant Allele: Expression of the phenotype occurs if the dominant allele is inherited from one or both parents (Aa or AA).

  • Recessive Allele: Expression requires both alleles to be recessive (aa); expression is only visible in homozygous recessive individuals.

  • Definitions:

    • Heterozygous: Inheriting two different alleles (Aa).

    • Homozygous: Inheriting two identical alleles (AA or aa).

PUNNETT SQUARES

  • Example: A heterozygous mother with a homozygous father.

    • Question: What would a Punnett square look like if both parents are heterozygous?

    • Consideration: Change in the probability of children being heterozygous or homozygous for alleles.

HUMAN DIVERSITY

  • Focus on Ancestry: Ancestry is a better label than "race" for genetic research.

    • Genetic Variation: There is more genetic variation within so-called "races" than between them.

GENE-ENVIRONMENT INTERACTIONS

  • Range of Reaction: Gene sets boundaries and the environment interacts with these set boundaries to determine individual outcomes.

  • Genetic Environmental Correlation: Genes influence the environment and vice versa.

  • Epigenetics: Study of how gene-environment interactions lead to different phenotypes from the same genotype.

INTERACTION EXAMPLE

  • High Genetic Risk Adoptees:

    • Raised in disturbed family environments: 36.8% likelihood to develop schizophrenia.

    • Raised in healthy family environments: 5.8% likelihood to develop schizophrenia.

  • Low Genetic Risk Adoptees:

    • Raised in disturbed family environments: 5.3% likelihood to develop schizophrenia.

    • Raised in healthy family environments: 4.8% likelihood to develop schizophrenia.

NERVOUS SYSTEM - NEURON STRUCTURE

  • Neurons: Various types, all structurally similar but with different functions.

    • Some have many dendrites and long axons (e.g., sending messages from spinal cord to limbs).

    • Discovery: Santiago Ramon y Cajal refined techniques to view individual neurons, establishing that they are distinct entities.

NEURON STRUCTURE ILLUSTRATION

  • Myelination: Neurons are covered in a myelin sheath, aiding signal transmission speed.

    • Terminal Buttons: End of the axon, containing synaptic vessels that store neurotransmitters.

THE SYNAPSE

  • Definition: A synapse consists of the terminal button of one neuron, the synaptic cleft, and the receiving endpoint of another neuron.

  • Action Potential: An electrical signal that is an all-or-none response, meaning it does not vary in amplitude or velocity but can change in frequency based on stimulus intensity.

NEUROTRANSMITTERS

  • Definition: Chemical messengers of the nervous system; different ones have various functions.

  • Biological Perspective: Psychological disorders such as depression and schizophrenia can be linked to neurotransmitter imbalances.

  • Key Neurotransmitters:

    • Beta-endorphin: Associated with pain relief and pleasure.

    • Dopamine: Influences mood, sleep, and learning.

    • Norepinephrine: Related to heart function, alertness, and intestines.

    • Serotonin: Affects mood and sleep.

DRUGS AND NEUROTRANSMITTER BALANCE

  • Psychotropic Medication: Drugs that alleviate psychiatric symptoms by restoring neurotransmitter balance.

    • Agonist: Mimics or enhances neurotransmitter effects.

    • Antagonist: Blocks neurotransmitter activity; used to correct imbalances (e.g., Dopamine agonists for Parkinson’s and antagonists for schizophrenia).

PARTS OF THE NERVOUS SYSTEM

  • Divisions:

    • Central Nervous System (CNS): Brain and spinal cord.

    • Peripheral Nervous System (PNS): Relays information to and from CNS; made of somatic and autonomic systems.

    • Somatic: Relays sensory/motor information; controls voluntary actions.

    • Autonomic: Regulates internal organs; divides into:

      • Sympathetic (fight or flight traits)

      • Parasympathetic (rest and digest)

THE BRAIN AND SPINAL CORD

  • The Brain: Consists of billions of interconnected neurons and glia; separated into various functional lobes.

  • The Spinal Cord: Transmits messages between the brain and body, functionally organized into 30 segments associated with distinct body parts. Reflexes can occur independently of the brain.

CORPUS CALLOSUM

  • Definition: A thick band of neural fibers connecting left and right hemispheres.

  • Lateralization: Each hemisphere specializes in different functions; left hemisphere controls right side of the body and vice versa.

BRAIN STRUCTURES: FOREBRAIN, MIDBRAIN, HINDBRAIN

  • Forebrain: Largest part; responsible for higher-level brain functions and structures like the cerebral cortex, thalamus, and hypothalamus.

  • Midbrain: Involved in controlling motor functions and regulating arousal and alertness.

  • Hindbrain: Controls automatic processes like breathing and heart rate; includes medulla, pons, and cerebellum.

BRAIN IMAGING TECHNIQUES

  • CT Scan: Uses x-rays to produce images show brain density.

  • PET Scan: Visualizes brain activity through blood flow changes using a radioactive tracer.

  • MRI: Uses magnetic fields for structural imaging.

  • fMRI: Monitors metabolic activity changes over time.

  • EEG: Records electrical brain activity via electrodes.

ACTION POTENTIAL

  • Process: Triggered by neurotransmitter binding; voltage changes lead to action potential generation if the threshold of excitation is reached.

    • Key Terms:

    • Depolarization: Neuron becomes less negative, increasing likelihood of firing.

    • Hyperpolarization: Neuron becomes more negative, decreasing likelihood of firing.

  • All-or-None Principle: Action potentials either occur fully or not at all; intensity of stimulation affects firing frequency.

REUPTAKE OF NEUROTRANSMITTERS

  • Process: Post-action potential, neurotransmitters are reabsorbed into the axon terminal or broken down to restore balance in the synapse.

MAJOR NEUROTRANSMITTERS AND BEHAVIORS

  • Acetylcholine: Muscle action & memory; affects arousal and cognition.

  • Beta-endorphin: Pain & pleasure; decreases anxiety and tension.

  • Dopamine: Mood, sleep, and learning; influences pleasure and appetite.

  • GABA: Brain function & sleep; reduces anxiety and tension.

  • Glutamate: Memory & learning; enhances memory and learning processes.

  • Norepinephrine: Affects heart, intestines, and alertness; increases arousal and suppresses appetite.

  • Serotonin: Regulates mood and sleep; assists in mood modulation and appetite suppression.