Essentials of Human Anatomy & Physiology: The Reproductive System

The Reproductive System

• Gonads (primary sex organs)

  • Testes in males

  • Ovaries in females

• Gonads Functions

  • Produce gametes (sex cells) and secrete hormones

  • Sperm - male gametes

  • Ova (eggs) - female gametes

  • Remaining structures are accessory reproductive organs

Functions of the Reproductive Systems

• Produce offspring via gametes

• Sperm and egg fuse to form a zygote

• Female uterus houses the embryo and later the fetus until birth

Anatomy of the Male Reproductive System

• Testes - primary male reproductive organ

• Duct System:

  • Epididymis

  • Ductus (vas) deferens

  • Urethra

• Accessory Organs:

  • Seminal glands (vesicles)

  • Prostate

  • Bulbourethral glands

• External Genitalia:

  • Penis

  • Scrotum

Testes

• Each testis connected to the trunk via the spermatic cord (houses blood vessels, nerves, ductus deferens)

• Coverings of the Testes:

  • Tunica albuginea - capsule around each testis

  • Septa - extensions dividing the testis into lobules

• Each lobule contains 1 to 4 seminiferous tubules (sperm-forming factories)

• Sperm travels from rete testis to epididymis

• Interstitial cells produce androgens (e.g., testosterone)

Duct System in Males

• Transports sperm from the body:

  • Epididymis

  • Highly convoluted tube (~ 6 m long)

  • Temporary storage site for immature sperm

  • Sperm mature during this journey

  • Ductus (vas) deferens

  • Runs from epididymis through inguinal canal and over urinary bladder

  • Ends at ampulla which empties into ejaculatory duct

  • Moves sperm by peristalsis during ejaculation

  • Urethra

  • Extends from urinary bladder to penis tip

  • Carries both urine and sperm

• Urethra regions:

  • Prostatic urethra- surrounded by prostate gland

  • Membranous urethra- prostatic urethra to penis

  • Spongy (penile) urethra- runs the length of the penis to the external urethral orifice

Accessory Glands and Semen

• Seminal Vesicles

  • Produce thick, yellowish secretion containing fructose, vitamin C, and prostaglandins (60% of semen)

• Prostate

  • Encircles upper urethra; secrets milky fluid to activate sperm

• Bulbourethral Glands

  • Produce thick mucus to cleanse urethra and lubricate

• Semen

  • Milky mixture of sperm and gland secretions; transports, nourishes sperm, and neutralizes vaginal acidity

External Genitalia in Males

• Scrotum

  • Sac of skin housing testes; needed for viable sperm production at cooler temperatures

• Penis

  • Male organ of copulation; delivers sperm; consists of shaft, glans penis, and prepuce (foreskin)

Male Reproductive Functions

• Responsibilities:

  • Produce sperm

  • Produce testosterone

Spermatogenesis

• Sperm Production

  • Starts at puberty, continues throughout life

  • Millions are formed daily in seminiferous tubules

  • Triggered by FSH secretion

• Each spermatogonium divides to produce:

  • Type A (stem cell)

  • Type B (primary spermatocyte for meiosis)

Testosterone Production

• Testosterone

  • Key hormonal product; stimulates reproductive organ development

  • Induces secondary sex characteristics

  • Deep voice

  • Increased muscle mass

Anatomy of Female Reproductive System

• Ovaries - produce eggs (ova), estrogen, and progesterone

• Duct System:

  • Uterine tubes

  • Uterus

  • Vagina

• External Genitalia

  • Including the vulva

Ovarian Cycle and Oogenesis

• Oogenesis: Process producing eggs in females

• Maturation of follicles and ovulation occurs cyclically

Uterine Cycle (Menstrual Cycle)

• Cyclic changes of the endometrium (28 days)

  • Regulated by estrogen and progesterone

  • Stages: Menstrual phase, Proliferative phase, Secretory phase

  • LH triggers ovulation

Pregnancy and Development

• Pregnancy Duration: Approximately 280 days from the last menstrual period

• Fertilization Process

• Zygote undergoes rapid divisions (cleavage) and forms a blastocyst

• Implantation: Blastocyst attaches to the endometrium

• Mammary glands develop and prepare for lactation

Childbirth and Labor

• Stages of labor:

  • Dilation, Expulsion, and Placental

  • Contractions regulated through hormonal feedback mechanisms

Contraception

• Various methods including hormonal pills, emergency contraceptives, and surgical options like tubal ligation and vasectomy.