Chapter 3B: Biology and Behavior

Vocabulary flashcards covering key terms from Chapter 3: Biology and Behavior.

Peripheral Nervous System (PNS)

Network of nerves outside the central nervous system that connects the CNS to the skin, muscles, glands, and internal organs; includes the Somatic and Autonomic nervous systems.

Somatic Nervous System (SNS)

Transmits sensory signals and motor signals between the central nervous system and the skin, muscles, and joints.

Autonomic Nervous System (ANS)

Transmits sensory and motor signals between the central nervous system and the body's glands and internal organs; regulates involuntary functions.

Central Nervous System (CNS)

The brain and spinal cord; processes information and coordinates activity.

Sympathetic Nervous System

Division of the ANS that prepares the body for action and energy expenditure (fight-or-flight).

Parasympathetic Nervous System

Division of the ANS that promotes rest and energy storage (rest-and-digest).

Homeostasis

Regulation of important body functions (e.g., temperature, thirst) to maintain internal stability.

Fight-or-Flight Response

The body's rapid reaction to stress, activating the sympathetic division to prepare for action.

Endocrine System

Glands that release hormones into the bloodstream to communicate with other body parts; responds to nervous system input, especially from the hypothalamus.

Hormones

Chemical messengers released by endocrine glands that regulate body processes.

Hypothalamus

Brain region that regulates the endocrine system and is a key input to the pituitary.

Pituitary Gland

The master gland; releases hormones that activate other glands and is regulated by the hypothalamus.

Pineal Gland

Gland that helps regulate body rhythms and sleep cycles.

Thyroid Gland

Gland that regulates the rate of metabolism in the body.

Adrenal Glands

Glands that secrete hormones for arousal, stress response, salt balance, and sexual functioning.

Pancreas

Gland that releases insulin to regulate blood sugar and hunger.

Testosterone

Male sex hormone produced by the testes; influences sexual function and puberty.

Estrogen

Female sex hormone produced by the ovaries; influences sexual function, puberty, and menstruation.

Ovaries

Female reproductive glands that secrete estrogen.

Testes

Male reproductive glands that secrete testosterone.

Genome

Master blueprint for making an organism; environment helps determine which genetic options are taken.

Chromosomes

Structures within cells made of DNA that contain genes.

DNA

Double-stranded helix made of the bases A, T, G, and C; hereditary material.

Gene

Unit of heredity that helps determine characteristics of an organism.

Gene Expression

Whether a gene is turned on or off and where in the body it is expressed.

Genotype

An organism’s entire genetic makeup.

Phenotype

Outward expression of genes; observable traits.

Sex Chromosomes

X and Y chromosomes that determine sex; maternal contribution is typically X.

XX

Female sex chromosome pair in humans.

XY

Male sex chromosome pair in humans.

Sperm

Male gamete carrying either an X or a Y chromosome.

Egg

Female gamete carrying an X chromosome.

Allele

Alternate form of the same gene for a trait.

Dominant Gene

Gene that is expressed in offspring whenever present.

Recessive Gene

Gene expressed only when paired with a similar gene from the other parent.

Homozygous

Having two identical alleles for a trait (e.g., CC or cc).

Heterozygous

Having two different alleles for a trait (e.g., Cc).

Genetic Drift

Random change in allele frequencies in a population due to chance.

Founder Effect

Extreme genetic drift when a small group establishes a new population, potentially altering allele frequencies.

Sickle Cell

An example where one allele changes red blood cell shape, illustrating allele variation.

Allele Frequencies

Proportions of different alleles in a population, which can affect survival.

Sexual Reproduction and Variation

Reproduction that increases genetic diversity, aiding adaptation and evolution.

Behavioral Genetics

Study of how genes and environment interact to influence psychological traits.

Twin Studies

Research comparing monozygotic (identical) and dizygotic (fraternal) twins to assess genetic influence.

Monozygotic Twins

Identical twins arising from a single zygote that splits; share the same genes.

Dizygotic Twins

Fraternal twins arising from two separate fertilized eggs; genetically no more similar than non-twin siblings.

Adoption Studies

Research comparing biological relatives and adoptive relatives to separate genetic and environmental influences.

Minnesota Twin Project

Famous adoption/twin study used to investigate heritability and environment.

Heritability

Statistical estimate of how much variation in a trait within a population is due to genetics; refers to populations, not individuals.

Gene-Environment Interaction

Idea that genes and environment interact to influence psychological traits.