Urinary and Genital Systems

• The urinary tract removes substances from blood, regulates processes, forms urine, and transports it out.
• The genital system's major function is reproduction.

Urinary Tract

• Includes the kidneys, ureters, bladder, and urethra.
• Kidneys filter metabolic wastes from the blood.
• Ureters are tubes from kidneys to the bladder.
• The bladder stores urine and empties into the urethra.
• In males, the urethra is part of both urinary and reproductive tracts.
• In females, the urethra is separate from the vagina.

Defenses and Normal Biota

• Flushing action of urine is a key defense mechanism.
• Urine flow encourages shedding of epithelial cells, removing attached microorganisms.
• Normal GI tract biota are a common microbial threat.
• Urinary tract epithelial cells have different surface chemicals than GI tract cells.
• Urine contains lysozyme (breaks down peptidoglycan) and lactoferrin (inhibits bacterial growth).
• Secretory IgA specific for previously encountered microorganisms is present.

Male Reproductive System

• Produces, maintains, and transports sperm cells; source of male sex hormones.
• Consists of testes (produce sperm/hormones), epididymides (coiled tubes from testes), and vas deferens (connects to seminal vesicle).
• The vas deferens combines with the seminal vesicle and terminates in the ejaculatory duct.
• The prostate gland contributes to semen.
• External organs: scrotum (containing testes) and penis (houses urethra).
• The flushing action of urine aids in defense.

Female Reproductive System

• Includes the uterus, fallopian tubes, ovaries, and vagina.
• An egg is released from an ovary approximately every 28 days during childbearing years.
• Fertilization may occur in the fallopian tubes.
• The fertilized egg moves to the uterus for implantation.
• Menstruation occurs if fertilization does not happen
• The vagina is the exit for fluids, channel for childbirth, and receptive chamber for the penis.
• The cervix connects the uterus to the vagina and is a common infection site.

Female Reproductive Tract Defenses

• Defenses vary over a woman's lifetime.
• Mucus in the vagina provides protection.
• In childhood and postmenopause, mucus and secretory IgA are the main defenses.
• During reproductive years, estrogen lowers vaginal pH due to glycogen secretion.
• Low pH prevents harmful microbes that might affect a fetus.
• Before puberty, low estrogen leads to a pH of about 7.

Normal Biota of the Genitourinary Tract

• The outer urethra has some normal biota.
• The kidney, ureters, bladder, and upper urethra may contain unculturable microbiota.
• Women have microorganisms like nonhemolytic streptococci, staphylococci, corynebacteria, lactobacilli, Prevotella, Veillonella, and Gardnerella.
• Microbial composition varies among individuals.
• In women, the short urethra near the anus facilitates urinary tract infections.
• Circumcision affects the normal biota on the penis.

Normal Biota of the Male Genital Tract

• The urethra contains residents colonizing the penis.
• Lactobacillus and Streptococcus species are found in the urethra of healthy men.
• The microbiota shifts after sexual activity, potentially including STIs

Normal Biota of the Female Genital Tract

• The uterus and above may have "trespassers" or permanent residents.
• The vaginal canal is colonized by diverse microorganisms.
• Before puberty and after menopause, the vaginal pH is close to neutral, harboring a biota similar to the urethra.
• Estrogen production after puberty leads to glycogen release and acidic pH.
• Lactobacillus species thrive in the acidic environment in women of childbearing age.
• Vaginal microbial makeup can shift during the menstrual cycle and pregnancy.
• There's no stable "core" vaginal biota composition during childbearing years.

Vaginal Microbiome

• Disruption of the vaginal microbiome can result in bacterial vaginosis (BV), aerobic vaginitis (AV), and vulvovaginal candidiasis (VVC).
• Imbalances are associated with douching, multiple sex partners, smoking, and obesity, and can increase the risk of sexually transmitted infections, cervical cancer, endometriosis, and decreased fertility.
• In pregnant women, dysbiosis can cause the fertilized egg to grow outside the uterus and increase the risk of preterm delivery, due to the beneficial microbes not being passed onto newborns vaginally.
• Diagnosis is complex and not straightforward based on Gram stain and microscopy.
• Treatments often cause loss of the beneficial bacteria.
• Probiotic lactobacilli have been proposed to aid in treatment and recovery.

Further Info on the Microbiome

• The estrogen-glycogen effect lasts until menopause.
• Postmenopausal women have stable biota composition.
• Lactobacillus and Gardnerella species are common, but other microbial species decrease.
• Decreased Lactobacilli is linked to vaginal dryness.
• Candida albicans is present at low levels in the healthy female reproductive tract.