PSYC 100 Lecture Notes - Lecture 2: Queen Ant, Y Chromosome, Fetus
8 Oct 2016
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PSYC100 Week 2 Lecture Notes
Developmental Psychology - Physical and Lifespan Development
Sex
- 200-300 years ago the term “sex” was used in a very limited manner
• state of being male or female (you “were” male or “female”)
• you couldn’t “have” sex in those days
- Starting about 100 years ago “sex” began to be used more broadly
• could now “have” it
• can refer to many/all aspects of sexual activity
• now different terms used to refer to different aspects of being “male” or “female”
Biological Sex
- Femaleness or maleness as indicated by chromosomes, reproductive organs, hormones,
and autonomy
• at birth, anatomy rules the decision as to whether the infant is a “boy” or a “girl”
o but this decision is actually more complex than one might think, especially
when considering sex determination in the animal kingdom
- other animal groupings have different ways of producing males and females
- for ants – if the queen ant produces an ant through the sperm fertilization if she stays with
the leg and harvests it then it will be a female – however is she just lays the egg and
leaves it alone then the ant will be a male
1.) Chromosomal (genetic) sex
• Human cells typically contain 23 pairs of chromosomes
o chromosomes house DNA
• One pair of the 23 is the sex chromosome pair
o an egg donates and X chromosome to this pair, and the sperm donates
either an X or Y chromosomes
• XX is associated with male and XY with female
2.) Reproductive organs (that produce reproductive cells or sex cells: testes and ovaries)
• Before the 7th week of gestation, the fetus has no gonads
o Only possesses chromosomal sex at this point, so the internal structures
have not yet developed
o If there is no Y chromosome by the 9th week of gestation then SRY does
not get activated (since it is not present) and ovaries will develop
3.) Hormones
• Just a little fact
o There are no “male” or female” hormones
o Both male and female bodies manufacture estrogen and testosterone
o It is the balance of these hormones that different between male and female
bodies
→ male bodies produce more testosterone
primarily in the testes
→ female bodies produce more estrogen
primarily by the ovaries
• In male fetuses
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Document Summary
200-300 years ago the term sex was used in a very limited manner: state of being male or female (you were male or female , you couldn"t have sex in those days. Hormones: just a little fact, there are no male or female hormones, both male and female bodies manufacture estrogen and testosterone, it is the balance of these hormones that different between male and female bodies. Male bodies produce more testosterone primarily in the testes. Female bodies produce more estrogen primarily by the ovaries. In male fetuses: it is the presence of testosterone and mullein inhibiting substance (mis; another hormone) that leads to male genitals, if this combination (t+mis) is not present, then female genital develops. Anatomy: development of male or female genitals (sexual organs) at about 16-week gestation, penis or vulva/vagina, serve non-productive as well as reproductive functions) whereas the testes and ovaries the gonads only serve reproductive functions)
