1.1-1.3 REVIEW

Terms to Know

1. Neuron:

  1. Parts and functions of the neuron (deterioration of myelin sheath*)

    Parts and Functions of Neurons

    1. Cell Body (Soma): Contains the nucleus and organelles; integrates signals and maintains cell health.

    2. Dendrites: Branch-like structures that receive signals from other neurons and transmit them to the cell body.

    3. Axon: A long, thin projection that transmits electrical impulses away from the cell body to other neurons or muscles.

    4. Myelin Sheath: A fatty layer that insulates the axon, speeding up signal transmission. Deterioration leads to slower communication (e.g., in multiple sclerosis).

    5. Axon Terminals: End points of the axon that release neurotransmitters to communicate with other neurons.

    6. Synapse: The gap between neurons where neurotransmitters are released, facilitating communication.

    Concepts

    • Neurons communicate through electrical impulses and chemical signals.

    • Myelin sheath integrity is crucial for efficient signal transmission.

  2. Types of Neurons: Sensory (Afferent), Interneuron, Motor (Efferent)

    Types of Neurons

    1. Sensory Neurons (Afferent Neurons)

      • Function: Transmit sensory information from receptors to the central nervous system (CNS).

      • Example: Neurons that carry signals from the skin, eyes, and ears.

    2. Interneurons

      • Function: Connect sensory and motor neurons within the CNS. They process information and coordinate responses.

      • Example: Neurons in the spinal cord that relay signals between sensory and motor pathways.

    3. Motor Neurons (Efferent Neurons)

      • Function: Carry signals from the CNS to muscles and glands, facilitating movement and responses.

      • Example: Neurons that stimulate muscle contraction.

    These neurons work together to enable sensory perception, reflexes, and motor control.

2. Neurotransmitters

  1. Functions and what happens when there is a shortage/surplus of that neurotransmitter

  2. Inhibitory/ Excitatory Neurotransmitters

  3. Agonist/Antagonist Drugs

    Functions of Neurotransmitters

    Neurotransmitters are chemical messengers that transmit signals across synapses between neurons. They play crucial roles in regulating mood, cognition, and bodily functions.

    Shortage/Surplus Effects

    • Shortage: Can lead to disorders. For example, low serotonin is linked to depression.

    • Surplus: May cause overstimulation. Excess dopamine can contribute to conditions like schizophrenia.

    Inhibitory vs. Excitatory Neurotransmitters

    • Inhibitory: Decrease neuron activity (e.g., GABA). They help calm the nervous system.

    • Excitatory: Increase neuron activity (e.g., glutamate). They promote alertness and learning.

    Agonist/Antagonist Drugs

    • Agonists: Mimic neurotransmitters, enhancing their effects (e.g., morphine mimics endorphins).

    • Antagonists: Block neurotransmitter effects (e.g., naloxone blocks opioids).

    These concepts are fundamental in understanding neurobiology and pharmacology.

    Neurotransmitters and Their Effects

    • Dopamine

      • Function: Reward, motivation, motor control.

      • Shortage: Parkinson's disease, depression.

      • Surplus: Schizophrenia, addiction.

    • Serotonin

      • Function: Mood regulation, sleep, appetite.

      • Shortage: Depression, anxiety disorders.

      • Surplus: Serotonin syndrome (confusion, rapid heart rate).

    • Norepinephrine

      • Function: Alertness, arousal, stress response.

      • Shortage: Depression, ADHD.

      • Surplus: Anxiety, high blood pressure.

    • GABA (Gamma-Aminobutyric Acid)

      • Function: Inhibitory neurotransmitter, calms nervous activity.

      • Shortage: Anxiety, seizures.

      • Surplus: Sedation, impaired motor function.

    • Glutamate

      • Function: Major excitatory neurotransmitter, learning, memory.

      • Shortage: Cognitive deficits.

      • Surplus: Neurotoxicity, seizures.

    Understanding these neurotransmitters is essential for grasping brain function and the effects of various drugs.

3. Nervous System

  1. Central Nervous System & its function/parts

  2. Peripheral Nervous System & its function/parts

    Central Nervous System (CNS)

    • Components: Brain and spinal cord.

    • Function: Processes information, coordinates activities, and controls behavior.

    • Parts:

      • Brain: Divided into cerebrum, cerebellum, and brainstem; responsible for thought, memory, and motor control.

      • Spinal Cord: Transmits signals between the brain and the body; involved in reflex actions.

    Peripheral Nervous System (PNS)

    • Components: Nerves outside the CNS.

    • Function: Connects the CNS to limbs and organs; facilitates communication.

    • Parts:

      • Somatic Nervous System: Controls voluntary movements and sensory information.

      • Autonomic Nervous System: Regulates involuntary functions (e.g., heart rate, digestion); divided into sympathetic and parasympathetic systems.

        Sympathetic Nervous System (SNS)

        • Function: Prepares the body for 'fight or flight' responses.

        • Effects: Increases heart rate, dilates airways, inhibits digestion, and releases adrenaline.

        • Neurotransmitters: Primarily uses norepinephrine.

        Parasympathetic Nervous System (PNS)

        • Function: Promotes 'rest and digest' activities.

        • Effects: Decreases heart rate, constricts airways, stimulates digestion, and conserves energy.

        • Neurotransmitters: Primarily uses acetylcholine.

        Concepts

        • Balance: Both systems work together to maintain homeostasis.

        • Autonomic Control: Operates involuntarily, regulating bodily functions without conscious effort.

4. Evolutionary Perspective

  1. Natural Selection, Survival of the Fittest

    Natural Selection and Survival of the Fittest

    Natural selection is a fundamental mechanism of evolution, proposed by Charles Darwin. It explains how species adapt over time through the following concepts:

    1. Variation: Individuals within a species exhibit variations in traits (e.g., size, color).

    2. Competition: Resources are limited, leading to competition for survival.

    3. Survival of the Fittest: Individuals with advantageous traits are more likely to survive and reproduce, passing those traits to the next generation.

    4. Adaptation: Over generations, beneficial traits become more common, leading to adaptations suited to the environment.

    This process drives evolution, shaping the diversity of life on Earth.

5. Biological Perspective

  1. Behavior geneticist and what their focus is

  2. Twin studies and what the findings are

  3. Genetic predisposition, chromosomes, prenatal environment, heritability

Behavior Geneticist

  • Focus: Behavior geneticists study the influence of genetics and environment on behavior. They explore how genetic predispositions interact with environmental factors to shape individual differences in behavior.

Twin Studies

  • Findings: Twin studies compare similarities between identical (monozygotic) and fraternal (dizygotic) twins. They help estimate heritability, revealing that genetics can account for a significant portion of behavioral traits, while environment also plays a crucial role.

Genetic Predisposition

  • Concept: Refers to the increased likelihood of developing certain traits or behaviors based on genetic makeup. It does not guarantee outcomes but indicates potential.

Chromosomes

  • Role: Structures within cells that contain DNA. Humans have 23 pairs, with genes located on these chromosomes influencing various traits.

Prenatal Environment

  • Impact: The environment in the womb, including nutrition, stress, and exposure to toxins, can affect fetal development and later behavior.

Heritability

  • Definition: A statistical estimate of the proportion of variance in a trait attributable to genetic factors within a specific population. It varies across traits and environments.