Unit 3 Biology Study Guide

Unit 3 Study Guide: Biological Bases of Behavior

BRAIN: Central Nervous System

• Components:

  • Central Nervous System: Brain and spinal cord.

  • Peripheral Nervous System:

    • Somatic Nervous System: Controls voluntary movements.

    • Autonomic Nervous System: Controls involuntary movements.

      • Parasympathetic Nervous System: Responsible for rest and digest functions.

      • Sympathetic Nervous System: Responsible for fight or flight responses.

NEURON STRUCTURE

• Parts of a Neuron:

  • Soma: Neuron's cell body; contains the nucleus.

  • Dendrites: Receive incoming signals from other neurons.

  • Receptor Sites: Locations on dendrites where neurotransmitters bind.

  • Axon: Long fiber that transmits signals away from the soma.

  • Myelin Sheath: Insulating layer that increases the speed of signal transmission.

  • Axon Terminal Branches: Endings of the axon that connect to other neurons.

  • Axon Terminal Buttons: Release neurotransmitters into the synapse.

  • Synapse: Gap where communication occurs between neurons.

NEUROTRANSMITTERS

• Key Neurotransmitters:

  • Dopamine: Involved in reward and pleasure.

  • Serotonin: Regulates mood, sleep, and appetite.

  • Norepinephrine: Affects mood and stress responses.

  • Glutamate: Major excitatory neurotransmitter; involved in learning.

  • GABA: Major inhibitory neurotransmitter; reduces neuronal excitability.

  • Endorphins: Pain relief; often linked to pleasure.

  • Substance P: Neurotransmitter related to pain perception.

  • Acetylcholine (ACh): Involved in muscle stimulation and memory.

  • Ghrelin: Increases appetite.

  • Leptin: Signals satiety.

  • Melatonin: Regulates sleep-wake cycles.

  • Oxytocin: Related to bonding and social behaviors.

  • Adrenaline (Epinephrine): Involved in fight or flight response.

BRAIN STRUCTURES

• Major Brain Areas:

  • Brain Stem: Controls basic life functions.

  • Medulla: Manages autonomic functions like breathing and heartbeat.

  • Reticular Activating System (RAS): Regulates alertness and arousal.

  • Cerebellum: Coordinates movement and balance.

  • Thalamus: Relay station for sensory information.

  • Cerebral Cortex: Higher-level brain functions.

    • Lobes:

      • Occipital Lobe: Vision.

      • Temporal Lobes: Auditory processing and memory.

      • Parietal Lobes: Processes sensory information.

      • Frontal Lobe: Executive functions, planning, and motor functions.

    • Corpus Callosum: Connects left and right hemispheres.

    • Somatosensory Cortex: Processes touch and pain sensations.

    • Prefrontal Cortex: Important for decision making and social behavior.

    • Motor Cortex: Controls voluntary muscles.

LIMBIC SYSTEM

• Components:

  • Hypothalamus: Controls hunger, thirst, and body temperature.

  • Hippocampus: Essential for memory formation.

  • Amygdala: Involved in emotion regulation and fear responses.

  • Pituitary Gland: Hormonal regulation, often called the master gland.

SLEEP

• Circadian Rhythms: Biological clock regulating sleep-wake cycles.

• Brain Waves during Sleep Stages:

  • Beta Waves: Alert, awake state.

  • Alpha Waves: Relaxed state.

  • Theta Waves: Light sleep.

  • Delta Waves: Deep sleep.

  • Sleep Spindles and K-complexes: Characteristics of sleep stages.

• Sleep Cycle: Includes NREM Stages 1-3 and REM Stage.

• Dream Theories:

  • Activation-Synthesis Theory: Dreams are byproducts of brain activity during sleep.

  • Information-processing Theory: Dreams help process information from the day.

• Sleep Theories: Explanations for the necessity of sleep.

• Sleep-wake Disorders:

  • Insomnia: Difficulty falling or staying asleep.

  • Narcolepsy: Sudden sleep attacks.

  • Sleep Apnea: Breathing interruptions during sleep.

  • Somnambulism: Sleepwalking.

SENSATION & PERCEPTION

• Sensation: Process of detecting stimuli.

  • Key Concepts:

    • Absolute Threshold: Minimum stimulus needed for detection.

    • Just-Noticeable Difference (JND): Minimum difference to detect change.

    • Weber’s Law: JND is proportional to the original stimulus.

• Visual Sensory System:

  • Key Components:

    • Retina: Light-sensitive layer at the back of the eye.

    • Rods: Detects light and dark.

    • Cones: Detects colors.

    • Fovea: Area of sharpest vision.

    • Lens: Focuses light onto the retina.

    • Optic Nerve: Transmits visual info to the brain.

    • Blind Spot: Area without photoreceptors.

    • Bipolar cells: Connect rods/cones to ganglion cells.

    • Ganglion Cells: Final output of retina.

  • Color Vision Theories:

    • Trichromatic Theory: Colors are perceived through three types of cones.

    • Opponent-Process Theory: Color perception is controlled by opposing colors.

• Auditory Sensory System:

  • Key Concepts:

    • Wavelength: Determines pitch.

    • Amplitude: Determines loudness.

    • Eardrum: Vibrates with sound waves.

    • Ossicles: Transmit vibrations to the oval window.

    • Oval Window: Membrane leading to cochlea.

    • Cochlea: Converts sound waves into neural signals.

    • Basilar Membrane: Contains hair cells responsible for sound transduction.

    • Auditory Cilia: Hair-like structures that detect sound.

  • Types of Hearing Loss:

    • Conduction Deafness: Problems in the outer/middle ear.

    • Sensorineural Deafness: Damage to inner ear or auditory pathways.

• Chemical Sensory System:

  • Olfactory Processing: How we detect smells.

  • Olfactory Bulb: Region where olfactory info first processes.

  • Gustatory Processing: Involves taste perception via taste receptor cells.

  • Five Types of Tastes: Sweet, sour, salty, bitter, umami.

• Touch Sensory System:

  • Somatosensory Cortex: Processes touch sensations.

  • Gate Control Theory: Explains how pain perception is modulated.

  • Phantom Limb: Sensation of pain or discomfort from a missing limb.

PERCEPTION

• Key Differences in Processing:

  • Bottom-up Processing: Analysis begins with the sensory input.

  • Top-down Processing: Uses prior knowledge to interpret sensory information.

• Influencing Factors:

  • Internal Factors: Schema (mental structures) and perceptual set (expectations).

  • External Factors: Context (surroundings) and experiences influencing perception.

• Gestalt Principles: Principles explaining how we naturally organize sensory input:

  • Closure: Filling in gaps to create a complete object.

  • Figure-ground: Differentiating parts of a visual field.

  • Proximity: Grouping nearby items together.

  • Similarity: Grouping similar items together.

• Attention:

  • Inattentional Blindness: Missing visible objects when focused elsewhere.

  • Change Blindness: Failing to notice changes in a visual scene.

• Depth Cues:

  • Binocular Cues: Use of both eyes for depth perception.

  • Monocular Cues: Depth cues available to either eye alone.

  • Linear Perspective: Depth perceived through the convergence of parallel lines.