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Anatomy & Physiology: The Reproductive System

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  • Gonads

    Gonads are organs that produce gametes and hormones in the reproductive system.

  • Male reproductive system primary functions

    Testes produce male sex hormones (androgens) and spermatozoa (sperm). Spermatogenesis occurs in testes, controlled by hormones from hypothalamus, pituitary, and testes.

  • Female reproductive system primary functions

    Ovaries release one immature gamete (oocyte) per month and produce hormones. Uterine tubes carry oocytes to uterus where fertilization occurs. Uterus supports embryo development. Vagina connects uterus to exterior.

  • Pathway of spermatozoa

    Testis → Epididymis → Ductus deferens (vas deferens) → Ejaculatory duct → Urethra.

  • Temperature regulation of testes

    Testes require temperatures about 1.1°C lower than body temperature. Dartos and cremaster muscles adjust scrotal position to maintain this temperature.

  • Tunica albuginea

    A dense connective tissue layer deep to tunica vaginalis, forming fibrous partitions (septa) within testes supporting blood vessels and ducts.

  • Seminiferous tubules

    About 800 tightly coiled tubules in testes lobules where sperm production occurs; each tubule is about 80 cm long.

  • Cells of spermatogenesis

    1. Spermatogonia (stem cells)
    2. Primary spermatocytes
    3. Secondary spermatocytes
    4. Spermatids
    5. Spermatozoa (mature sperm)

  • Difference between mitosis and meiosis in spermatogenesis

    Mitosis produces two diploid identical cells; meiosis produces four haploid cells with genetic variation for gametes.

  • Spermiogenesis

    Final stage of spermatogenesis where spermatids mature into spermatozoa, involving major structural changes.

  • Anatomy of spermatozoon

    Head contains nucleus and acrosomal cap with enzymes; middle piece has mitochondria for ATP; tail is flagellum for motility.

  • Functions of the epididymis

    Monitors and adjusts fluid from seminiferous tubules, recycles damaged sperm, stores and protects sperm, and facilitates sperm maturation.

  • Seminal glands (vesicles) function

    Produce about 60% of semen volume; seminal fluid contains fructose, prostaglandins, fibrinogen, and is slightly alkaline to aid sperm motility and neutralize acidity.

  • Prostate gland function

    Secretes slightly acidic prostatic fluid (20-30% of semen), contains antibiotic seminalplasmin, and helps propel semen into urethra by peristalsis.

  • Bulbo-urethral glands function

    Secrete thick, alkaline mucus to neutralize urinary acids in urethra and lubricate glans penis during sexual arousal.

  • Hormones controlling male reproduction

    FSH targets nurse cells to promote spermatogenesis; LH targets interstitial cells to produce testosterone, which stimulates sperm production and male secondary sex characteristics.

  • Functions of testosterone

    Stimulates spermatogenesis, libido, protein synthesis, muscle growth, and maintains male reproductive organs and secondary sex characteristics.

  • Oogenesis

    Production of female gametes (oocytes) in ovaries, begins before birth, accelerates at puberty, and ends at menopause.

  • Follicle development

    Primary oocytes are surrounded by follicle cells forming primordial follicles; monthly activation leads to follicular and luteal phases of ovarian cycle.

  • Uterine cycle phases

    Menses (degeneration of functional zone), proliferative phase (repair and growth of endometrium), and secretory phase (gland enlargement and secretion).

  • Functions of estrogen in female reproduction

    Stimulates bone and muscle growth, maintains secondary sex characteristics, increases sexual drive, maintains accessory glands, and initiates endometrial repair.

  • LH surge effects in ovarian cycle

    Triggers completion of meiosis I, follicle rupture, and ovulation about 34-38 hours after surge begins.

  • Progesterone role in luteal phase

    Maintains corpus luteum, supports secretory phase of uterine cycle, and declines if pregnancy does not occur, leading to menstruation.

  • Functions of the vagina

    Passageway for menstrual fluid, receives sperm during intercourse, and forms inferior portion of birth canal.

  • Female external genitalia components

    Includes vestibule (urethral and vaginal openings), clitoris (erectile organ), labia majora and minora, mons pubis, and associated glands.

  • Mammary glands function

    Specialized integumentary organs that secrete milk to nourish infants, controlled by reproductive hormones and placenta.

  • Male sexual function phases

    Arousal (parasympathetic stimulation causes erection), emission (sympathetic peristalsis moves sperm and fluids), and ejaculation (muscle contractions expel semen).

  • Menopause

    Time when ovulation and menstruation cease, typically between ages 45-55, with declining estrogen and progesterone and increased FSH and LH.

  • Male climacteric (andropause)

    Gradual decline in male reproductive function with decreasing testosterone, increased FSH and LH, but continued sperm production and reduced sexual activity.