Reproductive System

Reproductive System Overview

  • The reproductive system becomes active during puberty.

  • Gonads (primary sex organs):

    • Testes in males

    • Ovaries in females

  • Gonads produce gametes (sex cells) and secrete hormones:

    • Sperm is male gametes.

    • Ova (eggs) are female gametes.

Fertilization and Development

  • Fertilization occurs when sperm and egg unite, forming an embryo and later a fetus.

  • The fetus is housed in the uterus for about 9 months (38-40 weeks).

  • Sex hormones play a vital role in the development and function of reproductive organs and sexual behavior, influencing growth and development.

Male Reproductive System Anatomy

  • Testes:

    • Size: approximately 4 cm (1.5 inches) long, 2.5 cm (1 inch) wide.

    • Surrounded by tunica albuginea (connective tissue).

    • Contains septa and seminiferous tubules (sperm-forming factories).

  • Duct System:

    • Epididymis: A highly coiled tube (~6m or 20ft), stores immature sperm for about 20 days, maturing them.

    • Ductus (vas) deferens: Runs from epididymis through the inguinal canal into the pelvic cavity; ampulla expands at the end to empty into the ejaculatory duct.

  • Urethra: The terminal part of the male duct system, serving both urinary and reproductive functions.

Accessory Glands Producing Semen

  • Accessory Glands:

    • Include seminal vesicles, prostate, and bulbourethral glands.

  • Seminal Vesicles:

    • Produce 60% of seminal fluid (contains sugar, vitamin C, prostaglandins).

  • Prostate Gland:

    • Encircles the upper part of the prostatic urethra and produces a milky fluid activating sperm.

  • Bulbourethral Glands:

    • Produce clear mucus, cleansing the urethra of urine.

Spermatogenesis: Production of Sperm

  • Begins at puberty and continues throughout life, occurring in seminiferous tubules.

  • Millions of sperm produced daily; process takes 64 to 72 days.

  • Spermatogonia are primitive stem cells in the tubules, undergo rapid division until puberty.

  • Meiosis: Results in four sperm cells from each primary spermatocyte.

Female Reproductive System Anatomy

  • Ovaries: Composed of ovarian follicles, each containing a developing oocyte surrounded by follicular cells.

  • Ovarian Cycle includes cycles of follicle maturation and ovulation.

  • Uterine Tubes (Fallopian Tubes): Receive ovulated oocyte, provide a site for fertilization.

  • Uterus: Located between the urinary bladder and rectum; functions include housing the fertilized egg and nourishing it.

  • Vagina: Extends from the cervix to the exterior of the body, serves as the birth canal.

Hormonal Regulation in the Female Cycle

  • Menstrual Cycle: Cycles regulated by estrogen and progesterone, lasting approximately 28 days.

    • Phases:

      1. Menstrual Phase: Days 1-5, sloughing off functional layer of endometrium.

      2. Proliferative Stage: Days 6-14, endometrial regeneration.

      3. Secretory Stage: Days 15-28, preparing for implantation.

  • Ovulation occurs approximately on day 14.

Fertilization Process

  • The oocyte remains viable for 12-24 hours after ovulation; sperm for 24-48 hours post-ejaculation.

  • Successful fertilization requires intercourse within these time frames; results in a zygote (first cell of a new individual).

Pregnancy and Development Stages

  • Embryonic Development: From fertilization to 9 weeks.

  • Fetal Development: After 9 weeks, characterized by growth and specialization.

  • Placenta: Establishes connection with the embryo, delivering nutrients and removing waste.

Effects of Pregnancy on the Mother

  • Anatomical and physiological changes include:

    • Enlargement of the uterus and breasts.

    • Increased blood volume and pressure.

    • Morning sickness and other gastrointestinal issues.

Childbirth (Parturition)

  • Stages include dilation, expulsion, and placental stage.

  • Hormonal changes trigger labor, resulting in uterine contractions for delivery.