Understanding Heredity, Environment, and Evolution in AP Psychology

Heredity and environment form the foundational elements of human behavior and development. In the context of AP Psychology Unit 2: Biological Bases of Behavior, these concepts interweave to explain how genetic and environmental factors shape who we become. Chromosomes, containing 46 in 23 pairs, carry genetic information through DNA segments called genes that determine specific traits.

Definition: Heredity AP Psychology definition refers to characteristics genetically transmitted from parents to offspring through DNA, while Environment AP Psychology definition encompasses all non-genetic influences from conception to death.

Chromosomal abnormalities demonstrate the critical role of genetic structure in development. PKU, resulting from a mutation on chromosome 12, causes intellectual disability through protein buildup. Down Syndrome, characterized by an extra 21st chromosome, presents with distinctive physical features and varying degrees of intellectual disability. Klinefelter's Syndrome (XXY) and Turner's Syndrome (X) showcase how chromosomal variations affect physical and psychological development.

Research methods like twin studies have revolutionized our understanding of nature versus nurture. These investigations reveal how identical genetic makeup can produce different outcomes based on environmental factors. Rosenzweig's groundbreaking study demonstrated that environment influences neuroplasticity, showing how experience shapes brain structure and function.

Highlight: Evolutionary psychology applies natural selection principles to explain behavioral patterns, such as mate selection preferences where men typically favor physical features indicating youth and health, while women often prefer indicators of resources and social status.

Neural Communication and Neurotransmitter Function

Neural communication relies on specialized cellular structures and chemical messengers. The neuron's components - cell body, dendrites, axon, and terminal buttons - work together to process and transmit information through electrochemical signals.

Vocabulary: Action potentials are electrical signals that travel along axons, triggered when stimulation reaches a threshold level, following an all-or-none principle.

The process of neural transmission involves complex electrochemical changes. Starting from a negative resting potential, neurons generate action potentials when stimulated sufficiently. This leads to neurotransmitter release at synapses, followed by reuptake processes that restore the neuron to its resting state.

Neurotransmitters like acetylcholine play crucial roles in movement, memory, and learning. The balance of these chemical messengers is vital - too little or too much can lead to conditions like Alzheimer's disease or bipolar disorder, demonstrating the delicate nature of neural communication systems.

Brain Structure and Function

The human brain's complex architecture consists of specialized regions working in harmony. The AP Psychology Biological Bases of Behavior curriculum emphasizes understanding these structures and their functions.

Vocabulary: The cerebral cortex, the brain's outer layer, contains four major lobes: frontal, parietal, temporal, and occipital, each specialized for different functions.

The limbic system, often called the emotional brain, includes the hippocampus (crucial for memory formation) and the amygdala (processing fear and anger). The hypothalamus governs basic drives including hunger, thirst, and sexual behavior while coordinating with the endocrine system through the pituitary gland.

The brainstem handles vital functions like breathing and heartbeat through its components: the pons, medulla, and reticular formation. Meanwhile, the cerebellum coordinates balance and movement while supporting procedural memories.

Example: Damage to Broca's area in the left frontal lobe can result in speech production difficulties, while Wernicke's area damage in the temporal lobe affects language comprehension.