FEMALE REPRODUCTIVE SYSTEM

Primary Male and Female Sex Organs

  • Males: Primary sex organ is the testes.
  • Females: Primary sex organs are the ovaries, which produce haploid ova (eggs).

Structure of Ovaries

  • Cortex: The outer layer containing follicles; makes up the majority of the ovary.
  • Medulla: The inner layer that contains blood vessels, important for nutrient delivery and hormone circulation.

Sebaceous Glands and Protection

  • Sebaceous glands in the ovaries produce sebum, which helps protect against pathogens and bacteria.
  • Sebum is slightly acidic and contains components such as lysosomes to break apart foreign particles.

Sensation and Pleasure

  • The clitoris (female) and glans of the penis (male) are densely packed with nerve endings, contributing to sexual pleasure.

Mammary Glands and Lactation

  • Breasts: Part of the female reproductive system; contain mammary glands to produce milk for nursing.
  • Areola: The dark skin around the nipple with modified glands that help guide infants to the nipple.

Hormonal Control of Puberty

  • Puberty onset is initiated by a surge of gonadotropin releasing hormone (GnRH) from the hypothalamus.
  • Primary gonadotropins: Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH).

Female Puberty

  • FSH: Stimulates follicles in the ovaries, promoting secondary sex characteristics such as breast development, body fat distribution, and hair growth.
  • Estrogen and Progesterone: Important for the regulation of menstrual cycles, pregnancy, and secondary sex characteristics.

Oogenesis

  • Oogenesis: Differentiation of an ovum, paused mid-meiosis until puberty; monthly hormone cycles drive this process.

Menstrual Cycle Phases

  1. Menstruation: Typically lasts 5 days (Day 1 is the first day of menstrual flow).
  2. Follicular Phase: Starts with menstruation; involves the maturation of follicles and the proliferation of the uterine lining due to estrogen.
  3. Ovulation: Occurs around Day 14; triggered by a peak in LH.
  4. Luteal Phase: The corpus luteum forms, producing estrogen and progesterone for maintaining the uterine lining.

Requirements for Pregnancy

  1. Sperm must contact the egg within 24 hours post-ovulation.
  2. Fertilization occurs in the fallopian tubes.
  3. The fertilized egg (zygote) must implant into the uterine lining.

Stages of Development Post-Fertilization

  1. Zygote: Undergoes mitotic divisions after fertilization.
  2. Blastocyst: Refers to the implanted zygote, developing rapidly over approximately the first three weeks.
  3. Embryo: From weeks three to nine, organs and tissues begin to form.

Gestation Period

  • General length of gestation is 266 days from fertilization or 280 days from the last menstrual period (LMP).

Hormonal Regulation in Pregnancy

  • Corpus Luteum: Produces estrogen and progesterone in early pregnancy.
  • Placenta: Takes over hormone production, producing estrogen at levels up to 30 times higher than normal.
  • Progesterone: Suppresses gonadotropins (LH and FSH), preventing further ovulation and maintaining the uterine environment for the fetus.
  • Increases in aldosterone due to ACTH help with fluid maintenance during pregnancy.

Changes During Pregnancy

  • Increased breast tissue growth for lactation.
  • Hypertrophy of external genitalia and uterus to accommodate the growing fetus.
  • Increased elasticity of the pubic symphysis for childbirth.