In order to minimize the effects of crossing more than 3-4 time zones
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Steroid hormones Type of hormones, consists of 4 rings
(made of C – carbons). •Derived from cholesterol
•3 ways of action of steroid
Hormones: Binds to receptors in membrane. Binds to and activate proteins in
Cytoplasm. Acts on receptors linked to chromosomes. Sex hormones: Gonadal steroid hormones gonads: ovaries & testes •its hormones: gonadal steroids
•androgens (Testosterone, Dihydrotestosterone), •estrogens•progesterone But,
Gonads can produce both type of hormones (aromatase enzyme mediates
Conversions) Organizing effects of sex hormones •Hormonal effects on the
Brain and genitals. •Occurs in early stage of development. •Effects are long
Lasting (indefinitely).
Exps.: injections of androgens in female, or estrogens
In male, at early (sensitive) stage.
– Masculinization, feminization,
Lordosis.
The difference in external
Genitals appearance (female vs. Male) stem from gradients of testosteronein early
Sensitive period. •This “early sensitive period”: in humans (3 to 4 months
Pregnancy).Activating effects of sex hormones •Consists of hormonal effects
On the brain and genitals. •Occurs in later stage of development.
– Any time in
Life.
– Mediated by testosterone or estradiol
•Effects are limited on time
(temporal). The default tendency of
Nature is designed mammal for being female. Sex differences – Brain
(Hypothalamus) In early stage of development, sex hormones binds to
Receptors in Amygdala, Hypothalamus & others areas. Area of anterior
Hypothalamus: sexually dimorphic nucleus (SDN). Controls of male (M) sexual
Behavior. – Larger in male than female •In male rodents, testosterone induce
Part of its organizing effects by entering the neurons in hypothalamus, and being
Converted in estradiol,
Which helps to masculinize males. •Estradiol does not masculinize female,
Because Alpha-fetoproteinin rodents: binds to estrogen but not testosterone, controlling
Downstream effects.
•Removal of testes
– tendency to decreases male sexual activity. •Impotence(problems of erection) are explained by
Circulatory (blood), psychological tension, drugs, neurological problems, not
Necessarily testosterone changes. •If
Ovum fertilized, levels of estradiol and progesterone increases during
Pregnancy. These affects serotonin type 3 receptors (5HT-3R) activity, that is
Linked to nausea. • Periovulatory period
Women experiences changes in sex behavior and perceptions. High estrogen
Levels. – Effects in videos, work, faces Oxytocin:
Also released by posterior Pituitary. •Uterus contraction •Foster releases of
Mammary gland
(milk). •After sexual pleasures (orgasm) – linked to anxiolytic
Behavior.