Reproductive System Chapter 16

The reproductive system appears to “slumber” until puberty Gonads produce gametes (sex cells) and secrete sex hormones  Males produce sperm and female produce ova Ovum (plural: ova) – female gamete; egg

Anatomy of the Male Reproductive System

Testes Testes – male gonads Testes produce sperm and testosterone Approximately 4 cm (1 ½ inches) long and 2.5 cm (1 inch) wide

Testes Tunica albuginea (al”bu-jin’e-ah) – a white coat that surrounds each testis Seminiferous tubules – the actual “sperm- forming factories”

Epididymis Epididymis – the comma-shaped structure is a highly coiled tube about 20 feet long that caps the superior part of the testis Epididymis Testis

Epididymis The first part of the male duct system Provides a temporary storage site for the immature sperm that enter it from the testis Epididymis Testis

Epididymis Takes about 20 days for sperm to travel through the epididymis Afterwards, sperm have the ability to swim When a male is sexually stimulated, the epididymis expel the sperm into the vas deferens

Vas Deferens Vas deferens (or ductus deferens) – runs upward from the epididymis and arches over the superior aspect of the bladder

Vas Deferens Spermatic cord – the tube that encloses the vas deferens, blood vessels, and nerves in a connective tissue sheath

Vas Deferens Ejaculatory duct – the end of the vas deferens empties into this duct which passes through the prostate gland to merge with the urethra

Vas Deferens During ejaculation, the thick layers of smooth muscle in its walls create peristaltic waves that rapidly squeeze the sperm forward

Vas Deferens Vasectomy – a minor operation when the surgeon makes a small incision into the scrotum and then cuts through or cauterizes the vas deferens

Vas Deferens Vasectomy  Sperm are still produced, but they can no longer reach the body exterior and eventually deteriorate and are reabsorbed

Urethra Urethra – extends from the base of the urinary bladder to the tip of the penis; the terminal part of the male duct system

Urethra The male urethra carries both urine and sperm to the body exterior; thus, it serves the urinary and reproductive systems Urine and sperm never pass at the same time

Urethra When ejaculation occurs, the urethral sphincter contracts This event not only prevents the passage of urine into the urethra, but also prevents sperm from entering the urinary bladder

Prostate Gland Prostate gland secretion is a milky fluid that plays a role in activating sperm

Prostate Gland Since the prostate is located adjacent to the rectum, its size and texture can be felt by digital (finger) examination through the anterior rectal wall

Seminal Vesicles Seminal vesicle – a gland located at the base of the bladder

Semen Semen – a milky white, somewhat sticky mixture of sperm and accessory gland secretions  60-65% of the fluid is produced by the seminal vesicles  30-35% by the prostate  5% from the testicles (sperm)

Semen Semen is slightly alkaline ( pH level) Average number of sperm in one ejaculation: million Sperm can live 4-6 days in the female reproductive tract

External Genitalia Under normal conditions, the scrotum hangs loosely from its attachments, providing the testes with a temperature that is below body temperature

External Genitalia The scrotum, which provides a temperature about 3 degrees Celsius lower, is necessary for the production of healthy sperm

External Genitalia Penis – designed to deliver sperm into the female reproductive tract Glans penis – the enlarged tip of the penis Prepuce – foreskin around the proximal end of the glans

Spermatogenesis Spermatid (immature sperm)

Sperm

Anatomy of the Female Reproductive System Ovaries Fallopian tubes Vagina Uterus

Ovaries Ovaries – produce ova, estrogen, and progesterone

Ovaries Suspensory ligaments – structures used to secure the ovaries to the lateral walls of the pelvis

Fallopian (Uterine) Tubes Fallopian tubes – receive the ovulated oocyte and provide a site where fertilization can occur About 4 inches long

Fallopian (Uterine) Tubes Fimbriae (fim-bree-ee) – the distal ends of each fallopian tube with fingerlike projections which partially surround the ovary  Some eggs never reach the fallopian tubes Fimbria

Uterus Uterus (or womb) – a hollow organ that functions to receive, retain, and nourish a fertilized egg  About the size of a pear in a woman who has never been pregnant

Uterus Body – the major portion of the uterus Fundus – the superior rounded region of the uterus Cervix – the narrow outlet which is adjacent to the vagina

Uterus The uterus is consisted of three walls  Endometrium – the inner layer; the young embryo will attach to this layer during pregnancy  If a woman is not pregnant, this layer sloughs off about every 28 days (menstrual cycle)

Uterus  Myometrium – the bulky middle layer of the uterus; lined with smooth muscles that plays a role in delivery  Epimetrium – the outermost layer Epimetrium

Vagina Vagina – a thin-walled tube 3-4 inches long The vagina provides a passageway for the delivery of an infant and for menstrual flow to leave the body

Vagina Hymen – the distal end of the vagina tends to bleed when it is ruptured during the first sexual intercourse  Its durability varies Weak (torn during a sports activity) Strong (surgery is needed for intercourse to occur)

External Genitalia (Vulva) Mons pubis – a rounded mass of fatty tissue lying over the joint of the pubic bones

External Genitalia (Vulva) Labia majora – runs posterior from the mons pubis; two elongated hair-covered skin folds Labia minora – two delicate hair-free folds

External Genitalia (Vulva) Urethral opening – orifice urine exits the body Clitoris – composed of sensitive erectile tissue that becomes swollen with blood during sexual excitement (similar to the male penis)  Covered by prepuce (foreskin)

Oogenesis