Psych Chapter 10 Notes 10.1 How Does Biology Make Us Male or Female?Biological sexrefers to the physical factors that determine the sex of a person.There are five aspects of each person’s biological sex. When all these aspects of a person are consistent with each other, we usually say the person is either male or female.Five Aspects of Biological Sex:1.SEX CHROMOSOMESGenetic material determined at conception by the 23rdpair of chromosomes in the new zygote2.SEX GLANDSOrgans that release sex hormones and contain the cells used for sexual reproduction3.SECONDARY SEX CHARACTERISTICSChanges during puberty that are indirectly related to sexual reproduction4.PRIMARY SEX CHARACTERISTICSChanges during puberty that are directly related to sexual reproduction5.BRAINSDifferences in brain structure and in mental processes
Five Aspects in Males & Females:SEXCHROMOSOMES:FEMALESSex chromosomes:XX sex chromosomesSex glands:Ovaries release more estrogens and develop mature egg cellsSecondary sex characteristics:Increased release of estradiolDefining of waistIncrease in fatBreast developmentBody hair (armpits)Pubic hairPrimary sex characteristics:Mature internal organs (uterus and ovaries with egg cells)Mature genitals (vagina)MenarcheBrains:Less reactive amygdala and larger and more reactive orbitofrontal cortex create a tendency toward less physical aggressionMALESSex chromosomes:XY sex chromosomesSex glands:Testes release more androgens and develop mature sperm cellsSecondary sex characteristics:Increased release of testosteroneGreater muscle massFacial hairDeepening voiceAngular jawBody hair (armpits and chest)Pubic hairPrimary sex characteristics:Mature internal organs (testes w/ sperm cells)Mature genitals (penis)SpermarcheBrains:More reactive amygdala, smaller orbitofrontalcortex, and reduced coupling of amygdala andprefrontal cortex create a tendency toward greater physical aggression
When developing normally, the zygote contains all the genetic information from both parents in 46 chromosomes: 23 from the mother and 23 from the father. The 23rdchromosome from each parent determines the zygote’s biological sex.The mother’s egg cell always contributes an X chromosome as the 23rdchromosome. In about half ofconceptions, the father’s sperm cell also contributes an X chromosome so that the zygote has XX sexchromosomes. This makes the zygote a female.In about the other half of conceptions, the father’s sperm cell contributes a Y chromosome instead so the zygote has XY sex chromosomes. This makes the zygote a male.Thus, about half of babies are born with female sex chromosomes and half are born with male sex chromosomes. SEX GLANDS:Once the sex chromosomes of a zygote are determined, they also affect what sex glands, or gonads, the zygote will eventually develop.