The Endocrine System (the body’s chemical messenger system)

The Endocrine System  Network of glands that manufacture and secrete hormones  Hormones:  Chemical messengers in the bloodstream that regulate metabolism and influence body growth, mood, and sexual characteristics  Pulsatile release by endocrine glands  Negative feedback system

The Endocrine System: Glands & Hormones  Endocrine glands  Pituitary – “master gland,” growth hormone  Thyroid – metabolic rate  Adrenal – salt and carbohydrate metabolism  Pancreas – sugar metabolism  Gonads – sex hormones

The Endocrine System: Glands & Hormones  Pituitary gland  Secretes growth hormone and influences the secretion of hormones by other endocrine glands; attached to the hypothalamus  Testosterone/Androgen  Male sex hormone  Estrogen  Female sex hormone

Endocrine System

Evolution has fundamentally shaped psychological processes because it favors genetic variations that produce adaptive behavior How Are Genes and Behavior Linked?

 Innate – Inborn; present at birth; part of the organism’s biological heritage  Evolution – The gradual process of biological change that occurs in a species as it adapts to its environment

What is Biopsychology?  Biopsychology – The specialty in psychology that studies the interaction of biology, behavior, and the environment  Neuroscience – Interdisciplinary field that focuses on the brain and its role in psychological processes

Genes and Behavior: The Field of Behavioral Genetics  Behavioral genetics = the study of the influence of genetic factors on behavioral traits  Chromosomes – strands of DNA carrying genetic information  Human cells contain 46 chromosomes in pairs (sex-cells – 23 single)  Each chromosome – thousands of genes, also in pairs  DNA – a long, complex molecule that encodes genetic characteristics

Sex chromosomes – The X and Y chromosomes that determine our physical sex characteristics Genes influence our psychological characteristics as well as our physical traits Genes and Behavior: The Field of Behavioral Genetics

 Dominant, recessive  Homozygous, heterozygous  Genotype/Phenotype  Genotype – An organism’s genetic makeup  Phenotype – An organism’s observable physical characteristics  Polygenic Inheritance Genes and Behavior: The Field of Behavioral Genetics

Figure 3.25 Genetic material

Genes and Inheritance  Mutations – Genetic variations, which occur randomly, especially during the recombination of chromosomes in sexual reproduction

Figure 3.27 Genetic relatedness

Figure 3.28 Family studies of risk for schizophrenic disorders

Figure 3.30 Twin studies of intelligence and personality

Modern Approaches to the Nature vs. Nurture Debate  Molecular Genetics = the study of the biochemical bases of genetic inheritance  Genetic mapping – locating specific genes - The Human Genome Project  Behavioral Genetics  The interactionist model  Richard Rose (2000) – “Genes confer dispositions, not destinies.”

Evolution and Natural Selection  Natural selection – The driving force behind evolution, by which the environment “selects” the fittest organisms  Favorable adaptations to features of the environment allow some members of a species to reproduce more successfully than others

How Natural Selection Works Environmental pressure (changes in the environment) Competition (for resources) Selection of fittest phenotype (from among a variety of phenotypes) Reproductive success (genotype corresponding to fittest phenotypes passed to next generation) Frequency of that genotype increases (in next generation)

Natural Selection  Human evolution  Bipedalism  Encephalization  Language  Cultural evolution

Evolutionary Psychology: Behavior in Terms of Adaptive Significance  Based on Darwin’s ideas of natural selection  Reproductive success key  Adaptations – behavioral as well as physical  Fight-or-flight response  Taste preferences  Parental investment and mating

Research Methods in Behavioral Genetics  Family studies – does it run in the family?  Twin studies – compare resemblance of identical (monozygotic) and fraternal (dizygotic) twins on a trait  Adoption studies – examine resemblance between adopted children and their biological and adoptive parents