reproductive behavior sexuality and physiology l.
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Reproductive behavior: Sexuality and physiology. Hormones Organs Hypothalamus. Hormones. Neurotransmitters Neuromodulators or autacoids Hormones act on receptors Amino acid-based hormones Peptides and polypeptide proteins Steroids, from cholesterol Pheromones. Sex hormones.

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hormones
Hormones
  • Neurotransmitters
  • Neuromodulators or autacoids
  • Hormones act on receptors
    • Amino acid-based hormones
    • Peptides and polypeptide proteins
    • Steroids, from cholesterol
  • Pheromones
sex hormones
Sex hormones
  • Sex hormones are steroids
  • In addition to acting on surface receptors, steroids are fat-soluble and can enter cells to bind with internal receptors, even in the nucleus
  • Secreted by gonads and adrenal cortex, triggered by hypothalamus via the pituitary
estrogens and androgens
Estrogens and androgens
  • Gonads and adrenal cortex of both genders secrete both: The difference is in the relative amounts
  • Testosterone and estradiol
  • Progestins: Progesterone
  • Anterior pituitary: Gonadotropins and ACTH
  • Posterior pituitary: ADH and oxytocin
hypothalamic control
Hypothalamic control
  • Hypothalamus controls posterior pituitary through neurohormones released from axon terminals in PP
  • Hypothalamus controls anterior pituitary through releasing hormones secreted into a portal vein system.
sexual effects of hormones
Sexual effects of hormones
  • Fetal development
  • Perinatal development
  • Puberty
  • Adulthood
hormones in sexual development
Hormones in sexual development
  • Primordial gonads or fetal gonadal anlage are hermaphroditic: Medulla becomes testes, cortex becomes ovaries.
  • SRY gene on Y chromosome causes H-Y antigen to be synthesized, leading to development of medulla.
reproductive tracts
Reproductive tracts
  • Mullerian and Wolffian tissue develop under hormonal control
  • Testosterone triggers Wolffian development, MIS inhibits Mullerian development
  • Mullerian tissue develops by default unless MIS is present
other differentiation effects
Other differentiation effects
  • The external genitals develop in two different pathways from the same tissue, influenced by testosterone
  • Some brain structures develop different sizes or activity levels
    • Hypothalamus, corpus callosum, anterior commissure, thalamus, planum temporale
    • Temporal lobe and limbic system (more active in men); cingulate gyrus (more active in women)
brain effects of hormones
Brain effects of hormones
  • During early development, testosterone affects the hypothalamus by turning off the cycling pattern of gonadotropin release.
  • Testosterone acts on brain cells only after it is aromatized inside cells to estradiol, which then masculinizes the cells.
more on brain effects
More on brain effects
  • Estradiol in the mother’s blood is kept from the rat fetus by being bound by alpha fetoprotein; in humans by the placental barrier.
  • Synthetic estrogens, like DES, can cross the placental barrier, causing some masculinization in female children.
sexual effects of hormones12
Sexual effects of hormones
  • Fetal development
  • Perinatal development
  • Puberty
  • Adulthood
behavioral effects of hormones
Behavioral effects of hormones
  • In females:
    • In animal studies, perinatal testosterone treatment and ovariectomy leads to masculine sexual patterns (mounting) when testosterone is added at maturity.
    • When injected with progesterone and estradiol, they showed less female sexual response (lordosis).
sexual effects of hormones14
Sexual effects of hormones
  • Fetal development
  • Perinatal development
  • Puberty
  • Adulthood
hormones and puberty
Hormones and puberty
  • Timing by the hypothalamus SCN
  • Anterior pituitary and growth hormone
  • Gonadotropic and adrenocorticotropic hormones trigger greater increases in either androgens or estrogens, but both are secreted in increased amounts by both genders, eg. androstenedione
exceptional development
Exceptional development
  • Hermaphroditism
    • Androgen Insensitivity Syndrome
      • No receptors for androgens
    • Adrenogenital Syndrome
      • Insufficient cortisol to inhibit adrenal androgen
    • Sex reassignment
sexual effects of hormones17
Sexual effects of hormones
  • Fetal development
  • Perinatal development
  • Puberty
  • Adulthood
hormones and adults
Hormones and adults
  • Male sexual capacity and behavior relate to testosterone levels
    • Castration reduces sex drive and potency
    • Replacement testosterone increases sex drive and potency in men with a testosterone deficiency: castrati and elderly
    • Healthy males are unaffected by additional testosterone. They already have plenty.
sexual hormones in adult females
Sexual hormones in adult females
  • Sexual hormones do control the estrus cycle, which is related to sexual activity, and the menstrual cycle, which is not.
  • Ovariectomy does not reduce sex drive, if the consequent lack of lubrication is compensated.
  • Sexual interest appears to be controlled by testosterone.
other hormone effects
Other hormone effects
  • Social-cognitive functioning (Macrae et al., 2002)