Sex & Hormones

• Estrogens 


  hormones that are more abundant in females
• Are steroid hormones

  Androgens and estrogens
• which causes those primitive gonads to develop into testes, the sperm-producing organs.

  SRY (sex-determining region on the Y chromosome)
• hormones that are more abundant in males

  androgens
• The most widely known androgen

  testosterone.
• The most prominent type of estrogen

  estradiol
• another predominantly female hormone prepares the uterus for

  the implantation of a fertilized ovum and promotes the main-

  tenance of pregnancy.

  Progesterone
• produce long-lasting structural effects.

  Organizing effects
• are more temporary, when a hormone increases some activity that lasts only while the hormone is present.

  Activating effects
• when hormones determine whether an embryo develops a male or female anatomy.

  Sensitive period
• • one area in the anterior hypothalamus
  • is larger in males than in females and contributes to control of male sexual behavior.

  sexually dimorphic nucleus
• which is not present in adults

  alpha-fetoprotein
• which transmits tactile stimulation from the vagina and cervix to the brain

  pudendal nerve
• • which facilitate erection of the penis in the male
  • sexually receptive postures in the female

  type D1 and D5 receptors
• which leads to orgasm

  D2 receptors
• the inability to have an erection

  impotence
• a periodic variation in hormones and fertility over the course of about 28 days

  menstrual cycle
• which promotes the growth of a follicle in the ovary.

  follicle-stimulating hormone (FSH)
• from the anterior pituitary

  luteinizing hormone (LH)
• • The most widely used birth-control pill
  • containing estrogen and progesterone, prevents the surge of FSH and LH that would otherwise release an ovum.

  combination pill
• consisting of the days around the middle of the menstrual cycle, is the time of maximum fertility and high estrogen levels.

  periovulatory period
• stimulates contractions of the uterus during delivery of a baby, and it stimulates the mammary gland to release milk.

  Oxytocin