Presentation on theme: "Human Reproductive System Produces, stores, nourishes and transports functional gametes (egg and sperm)."— Presentation transcript:
Human Reproductive System Produces, stores, nourishes and transports functional gametes (egg and sperm).
2 o Reproductive Organs = External Genitalia Fertilization - union of sperm and egg = zygote. 1 o 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) F rom 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 Sex Apparent anatomical sex of individual Sexual differentiation Male Induced by Androgens Mostly Testosterone Female Lack of Androgens
Mullerian Inhibiting Factor Testosterone + Male
2 o Sexual Characteristic Differences in anatomy and physiology between males and females = sexual dimorphism. Males Females Pattern of hair growth Characteristic Voice (pitch) Muscle mass Bone growth/density Sex drive Distribution of body fat Aggression
Genetic and Phenotypic Sex If person with XY has testes that fail to differentiate 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 XXNormalXYNormal XOTurner XXYKlinefelter XXXTriple-XXYY
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. 1 o 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 2-3 o 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