bio lecture 1 Flashcards
What is a gonad?
An organ that produces gametes (sex cells) and reproductive hormones.
What are the two types of gonads?
Testes (Male Gonads) and Ovaries (Female Gonads).
What do testes produce?
Sperm and secrete testosterone.
What do ovaries produce?
Eggs (ova) and secrete oestrogen and progesterone.
What chromosomes determine sex?
XX (female) and XY (male) chromosomes.
What is the role of the SRY gene?
Activates testis development; absence results in ovary development.
What hormones does the early testis produce?
Anti-Müllerian Hormone and Androgens.
What does Anti-Müllerian Hormone do?
Defeminises by preventing female organ development.
What do androgens cause?
Masculinisation, leading to the development of male traits.
What are primary sexual characteristics in females?
Internal organs: uterus, fallopian tubes, and ovaries; External organs: vulva, clitoris, and vagina.
What are primary sexual characteristics in males?
Internal organs: vas deferens, epididymis, prostate, and seminal vesicles; External organs: penis and scrotum.
Vas deferens:
A muscular tube that transports sperm from the epididymis
What are organizational effects of hormones?
Effects that occur during critical periods and persist after hormone removal.
What are activational effects of hormones?
Temporary effects that depend on hormone presence.
What triggers the onset of puberty?
what do they do?
Kisspeptin and GnRH.
K= produced in hypothalamus and it stimulates the release of GnRH
GnRH= produced by the hypothalamus to signal pituitary gland to release LH and FSH
What is the hypothalamo-pituitary-gonadal (HPG) axis?
explain process…
A negative feedback loop:
- (kisspeptin, stress, puberty timing, and feedback from sex hormones) causes Hypothalamus to Releases GnRH
- GnRH travels to pituitary glang and stimulates release of LH and FSH
- LH and FSH travel in the bloodstream and tell the gonads to Make sex hormones and Produce gametes (sperm or eggs)
High levels of sex hormones send feedback to the brain to slow down GnRH, LH, and FSH.
What initiates the HPG axis process?
kisspeptin
What does the hypothalamus release in the HPG axis?
Gonadotropin-Releasing Hormone (GnRH).
What hormones do the anterior pituitary release?
Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH).
What do gonads produce in response to LH and FSH?
Testosterone (from testes) and Oestrogen/Progesterone (from ovaries).
HPG Axis- how do hormones regulate menstrual cycle through HPG axis
Follicular Phase
ovulation
luteal phase
What happens during the follicular phase of the menstrual cycle?
hypothalamus- GnRH- LH and FSH- FSH promotes follicle growth in the ovaries.- the developing follicle produces estradiol (a form of oestrogen)
What triggers ovulation?
Rising estradiol levels - surge in LH- causes ovulation (egg is released from the follicle into the fallopian tube)
What occurs during the luteal phase?
After ovulation, the empty follicle transforms into the corpus luteum- produces progesterone and oestrogen- if no pregnancy it degenerates after 2 weeks
What happens if no fertilization occurs?
Progesterone and oestrogen levels drop, triggering menstruation.
What is Androgen Insensitivity Syndrome (AIS)?
A condition where testosterone has no receptors to bind to, resulting in female anatomy despite XY chromosomes.
What is 5α-Reductase Deficiency?
Inability to convert testosterone to DHT, leading to female external genitalia but male internal organs.
What is Congenital Adrenal Hyperplasia (CAH)?
A condition causing excess prenatal testosterone in 46,XX individuals, leading to ambiguous genitalia and masculine traits.
What are structural differences in male and female brains?
Male brains are ~10% larger; female brains have a thicker cortex and more grey matter.
What are some functional differences in behaviour between boys and girls?
Different toy preferences, with boys showing a preference for cars and girls for dolls.
What influences sexual orientation?
Biological correlates such as brain differences in SCN, INAH-3, and anterior commissure.
What is the role of testosterone in sexual orientation?
It influences brain differentiation during critical periods of development.
What is the 2D:4D finger ratio?
The ratio of the height of the 2nd finger to the 4th finger, associated with prenatal testosterone exposure.
What cognitive performance differences exist between androphilic and gynophilic men?
Androphilic men show better verbal abilities than gynophilic men, while gynophilic men show better visuospatial abilities than androphilic men.
How do gynophilic and androphilic women compare in mental rotation tasks?
Gynophilic women are faster at mental rotation tasks than androphilic women.
What does the 2D:4D finger ratio indicate?
Lower ratios (shorter index finger relative to ring finger) are associated with higher prenatal testosterone.
What is the 2D:4D ratio trend among butch lesbians?
Butch lesbians tend to have more masculine 2D:4D ratios.
Are there consistent 2D:4D findings in androphilic men?
No consistent 2D:4D findings in androphilic men.
What are oto-acoustic emissions (OAEs)?
When ears are stimulated with a click, they emit a sound back.
How do women’s OAEs compare to men’s?
Women’s OAEs are louder and more frequent than men’s.
What effect does prenatal testosterone exposure have on OAEs?
Prenatal testosterone exposure reduces OAEs.
How do gynophilic women’s OAEs compare to gynophilic men’s?
Gynophilic women’s OAEs are closer to gynophilic men’s than to androphilic women’s.
What is the likelihood of CAH females being gynophilic?
CAH females are more likely to be gynophilic than non-CAH females.
What do twin studies suggest about genetic contributions to sexual orientation?
Higher concordance for sexual orientation in monozygotic twins than dizygotic twins.
What is the range of concordance estimates for sexual orientation?
Concordance estimates range from 30-100%.
Is heritability for sexual orientation possibly higher in men or women?
Possibly higher heritability for women than men.
What genetic link is suggested for androphilic men?
Androphilic men often have androphilic maternal uncles, suggesting an X-chromosome link.
What are potential explanations for the maintenance of non-reproductive orientations?
Heterozygote advantage, different genetic effects in males vs. females, and kin selection.
What is the Fraternal Birth Order Effect?
The more older brothers a male has, the higher the likelihood of being androphilic.
What is the maternal immune hypothesis?
Mother’s immune system reacts to Y-linked proteins, influencing brain development.
What influences sexual orientation?
Sexual orientation is influenced by biological developmental factors, hormonal, genetic, and environmental factors.
What brain differences are observed in MtF and FtM individuals?
MtF individuals show feminine cortical thickness, while FtM individuals show masculine basal ganglia.
What do twin studies indicate about gender dysphoria?
Higher concordance in monozygotic twins for gender dysphoria and sexual orientation.
What is the impact of environmental and cultural influences on sexual orientation?
Minimal effects on sexual orientation; social influences impact behavior, not orientation.
What are the conclusions about sexual differentiation and orientation?
Biological, hormonal, and genetic factors drive sexual differentiation and orientation.
