Human Reproductive System

Produces, stores, nourishes and transports functional gametes (egg and sperm).

2o Reproductive Organs = External Genitalia

Fertilization - union of sperm and egg = zygote.

1o Reproductive Organs = Gonads

Gonads make gametes (sex cells)and the Sex Hormones.

Ducts, accessory organs and glands assist gametes

• Male Gonads– Testes produce sperm and testosterone.

• Female Gonads– Ovaries produces eggs, estrogen and progesterone.

The Sex Chromosomes

XX or XY

Female Male

X chromosome has about 1,100 genes on it.

Y chromosome has about 80 genes on it.

22 pairs of autosomal chromosomes +

1 pair of sex chromosomes.

Platypus:Researchers discovered it has 10 sex chromosomes, some of them linked to mammals and some to birds.

Endocrine Regulation of Reproduction

Gonadotropin-releasing hormone (GnRH)

From Hypothalamus, stimulates FSH and LH release.

FSH:↑ follicular development, ↑ estrogen (females). Required for sperm production (males).

LH (ICSH in men): Ovulation. Regulates estrogen and progesterone (females). ↑ Testosterone (males)

Phenotypic SexApparent anatomical sex of individual

Sexual differentiation

Male

Induced by Androgens

Mostly Testosterone

Female

Lack of Androgens

MullerianInhibitingFactor

Testosterone +

Male

2o Sexual Characteristic

Differences in anatomy and physiology between males and females = sexual dimorphism.

Males FemalesPattern of hair growth

Characteristic

Voice (pitch)

Muscle mass

Bone growth/density

Sex drive

Distribution of body fat

Aggression

Genetic and Phenotypic SexIf person with XY has testes that fail todifferentiate and secret hormones - Result?

= genetic male, anatomical female

If person with XY has normal testosterone levels but target tissue lacks receptors - Result?

= genetic male, anatomical female (testicular feminization syndrome)

Sex Chromosome Abnormalities

Female Genotype

Syndrome Male Genotype

Syndrome

XX Normal XY Normal

XO Turner  XXY Klinefelter

XXX Triple-X XYY XYY

• Klinefelters’s Syndrome– Person has 47 chromosomes, the extra

one is a Y, genotype = XXY

• Turner’s Syndrome– Person has 45 chromosomes, the X or Y is

missing, genotype = XO

= Male

= Female

Reduced fertility, small testicles, enlarged breast

Usually Infertile, short, immature sex organs at adolescence

Triple-X Syndrome Women with 3X chromosomes - genotype is XXX “Super-females" or “Meta-females”. Taller, long legs, slender torsos, limited fertility. 

XYY Syndrome Males with extra Y chromosome - genotype is XYY.  “Super-males“ often tall, high testosterone levels.  Usually fertile. 

Both often unaware of chromosomal abnormality

Male Reproductive Structures

• Held ‘outside’ body in the scrotum.

1o Reproductive organ: Testes

• Dartos muscle wrinkles skin of scrotum.

• Cremaster muscle pulls testes closer to body.

Male Reproductive Structures

• Cremaster Reflex.

Epididymis ~ 18 feet long

~ 3 weeks to travel through

- Head

- Body

- Tail

Stores sperm, recycles

damaged ones, site of

maturation of sperm

Ductus deferens – starts after tail of epididymis

The Accessory Glands

Accessory Organs of the Male

1. Seminal vesicles

2. Prostate gland

2. Bulbourethral glands

All secrete semen

1. Seminal Vesicles• Paired glands - secretes 60% semen volume.

• Fibrinogen – converts to fibrin for clotting.• Fructose – a monosacharide for energy.

• Prostaglandins – contract female tract.

2. Prostate Gland• Single gland - secretes 30% semen volume.

• Clotting proteins – to cause initial clots.

3. Bulbourethral Glands

• Lubricating properties.

• Fibrolysin – to liquefy clots.

• Paired glands (~5% semen volume).

• Alkaline mucus secretion (to neutralize).

Semen

• Typical ejaculation releases 2-5 ml.

• Sperm count typically 50 – 100 million per ml.

• Sperm count below 20 million per ml, considered “infertile”.

• Sperm must be 2-3o F cooler than rest of body, hence kept ‘outside’ in scrotum.

The Penis

• Erectile tissue (3 masses)– Two corpora cavernosa– One corpus spongiosum (surrounds urethra)

• Erection – dilation of arterial smooth muscles.

Erectile Dysfunction (ED)?

The Female Reproductive System

• Vaginal canal and vagina

• External genitalia

• Ovaries

• Uterus

• Uterine tubes

Female Reproductive System

Uterine Wall (Layers)

• Myometrium – muscular (thickest ~90%).

• Endometrium - innermost layer

• Perimetrium – outermost covering.

– Functional layer, top 1/3 (sheds).

– Basal Layer, bottom 2/3 (remains).

The Vagina – passage, connecting uterus to external genitalia.

The External Genitalia:

Labia majora – outer (larger)

Labia minora – inner (smaller)

Lesser and greater vestibular glands.

Mons pubis

Clitoris – erectile tissue (spongiosum)(prepuce = hood, foreskin of clitoris)