Chapter 22 Reproductive Systems Male reproductive organs 1 Male Reproductive Organs posterior view 2 Male Reproductive Organs • Specialized to produce, maintain the male sex cells (sperm) • Transport these cells together with supporting fluids to the female reproductive tract • Secrete male sex hormones 3 1 Testes • Ovoid structure about 5 cm long and 3 cm in diameter • Suspended by spermatic cord • Contained within the cavity of the scrotum 4 Descent of the Testes During fetal development, each testis develops near a kidney and then descends through an inguinal canal and enters the scrotum completing the journey by the eighth gestational month. 5 Structure of the Testes Tunica albuginea Mediastium testes -septa -lobules Seminiferous Tubules Epididymis 6 2 Formation of Sperm Cells 7 Spermatogenesis 8 Crossing Over • mixes up genetic traits • different colors represent the fact that one homologous chromosome comes from the individual’s father and one from the mother 9 3 Crossing Over • the genetic information in sperm cells and egg cells varies from cell to cell 10 Blood-testis barrier • Prevents some substances from reaching the developing sperm • Helps maintain favorable environment by isolating sperm from the man’s immune system 11 Structure of a Sperm Cell 12 4 Male Internal Accessory Organs • epididymus • ductus deferens • seminal vesicles • prostate gland • bulbourethral glands 13 Epididymus • tightly coiled tubes • connected to ducts within testis • Support stored sperm • promote maturation of sperm cells 14 Ductus Deferens • muscular tubes • about 45 cm each • extends from epididymis to ejaculatory duct • Ampulla-expanded part of ductus deferens near the end • Passes through prostate into urethra 15 5 Seminal Vesicles • attached to ductus deferens near base of bladder • secrete alkaline fluid • secrete fructose and prostaglandins • contents empty into ejaculatory duct 16 Prostate Gland • surrounds proximal portion of urethra • ducts of gland open into urethra • secretes a thin, milky, alkaline fluid • secretion enhances fluid mobility • composed of tubular glands in connective tissue • also contains smooth muscle 17 Bulbourethral Glands • inferior to the prostate gland • secrete mucus- like fluid • fluid released in response to sexual stimulation 18 6 Semen • sperm cells • secretions of seminal vesicles, prostate gland, and bulbourethral glands • slightly alkaline • prostaglandins • nutrients • 120 million sperm cells per milliliter 19 Male External Reproductive Organs • scrotum • penis 20 Scrotum • pouch of skin and subcutaneous tissue • dartos muscle – smooth muscle in subcutaneous tissue; contracts to cause wrinkling of the scrotum • medial septum divides scrotum into two chambers • each chamber lines with a serous membrane • each chamber houses a testis and epididymis 21 7 Penis • conveys urine and semen • specialized to become erect for insertion into the vagina • circumcision 22 Penis 23 Erection, Orgasm, and Ejaculation Erection • parasympathetic nerve impulses • blood accumulates in erectile tissues Orgasm • culmination of sexual stimulation • accompanied by emission and ejaculation Ejaculation • emission is the movement of semen into urethra • ejaculation is the movement of semen out of the urethra • largely dependent on sympathetic nerve impulses 24 8 Hormonal Control of Male Reproductive Functions • hypothalamus controls maturation of sperm cells and development of male secondary sex characteristics • negative feedback among the hypothalamus, the anterior lobe of the pituitary gland, and the testes controls the concentration of testosterone 25 Actions of Testosterone • In fetus, stimulates formation of male reproductive organs and causes testes to descend • increased growth of body hair • sometimes decreased growth of scalp hair • enlargement of larynx and thickening of vocal cord • thickening of skin • increased muscular growth • thickening and strengthening of the bones • increases rate of cellular metabolism and production of rbc’s • male sex drive 26 Organs of the Female Reproductive System 27 9 Organs of the Female Reproductive System • Specialized to produce and maintain female sex cells (egg cells or oocytes) • Transport sex cells to the site of fertilization • Provides a favorable environment for a developing offspring • Move the offspring to the outside • Produce female sex hormone 28 Ovaries • Solid, ovoid structures 3.5 cm long, 2 cm wide and 1 cm thick • Held in place by several ligaments • Broad ligament-largest • Also attahed to uterus and uterine tube • Suspensory ligament-upper end • Ovarian ligament-attaches ovaries to uters 29 Ovary Structure • Medulla-outer part • Cotex-inner part • Ovarian follicles • Tunica albuginea 30 10 Primordial Follicles • Start meiosis before birth then stop until puberty 31 Oogenesis • the process of egg cell formation 32 Follicle Maturation Primordial follicle Mature (Graafian) follicle 33 11 Follicle Maturation 34 Ovulation 35 Ovulation 36 12 Female Internal Accessory Organs • uterine tubes • uterus • vagina 37 Uterine Tubes • convey eggs toward the uterus 38 Uterus • hollow muscular organ that receives the embryo that has been fertilized in the uterine tube 39 13 Uterine Wall 40 Vagina • fibromuscular tube that conveys uterine secretions, receives the penis during intercourse, and provides an open channel for offspring • hymen 41 Female External Reproductive Organs • labia majora • labia minora • clitoris • vestibule • vestibular glands 42 14 Labia Majora • rounded folds of adipose tissue and skin • enclose and protect the other external reproductive parts • ends form a rounded elevation over the symphysis pubis 43 Labia Minora • flattened, longitudinal folds between the labia majora • well supplied with blood vessels 44 Clitoris • small projection at the anterior end of the vulva • analogous to the male penis • composed of two columns of erectile tissue • root is attached to the sides of the pubic arch 45 15 Vestibule • space between the labia minora that encloses the vaginal and urethral openings • vestibular glands secrete mucus into the vestibule during sexual stimulation 46 Hormonal Control of Female Reproductive Functions • estrogens inhibit LH and FSH during most of the reproductive cycle 47 Effects of Estrogens • Stimulates enlargement of accessory organs • Stimulates the endometrium to thicken • Development and maintenance of female sexual characteristics • development of breasts and ductile system of the mammary glands • increased adipose tissue in breasts, thighs, and buttocks • increases vascularization of skin 48 16 Female Reproductive Cycle 49 Female Reproductive Cycle 50 Menopause • usually occurs in late 40s or early 50s • reproductive cycles stop • ovaries no longer produce as much estrogens and progesterone • some female secondary sex characteristics may disappear • may produce hot flashes and fatigue • May lead to osteoporosis • May cause migranes, backaches 51 17 Mammary Glands • specialized to secrete milk following pregnancy • composed of lobes • lobes contain alveolar glands drained by alveolar ducts which drain into alveolar ducts which drain into lactiferous ducts that leads to the nipple • estrogens stimulate breast development in females 52 Sexually Transmitted Diseases • silent infections • most are bacterial and can be cured • herpes, warts, and AIDS are viral and cannot be cured • many cause infertility • AIDS causes death • symptoms of STDs include • burning sensation during urination • pain in lower abdomen • fever or swollen glands • discharge from vagina or penis • pain, itch, or inflammation in genital or anal area • sores, blisters, bumps or rashes • itchy runny eyes 53 Clinical Application Prostate Enlargement • benign prostatic hypertrophy occurs in most men over 50 • BPH causes frequent urination • risk factors include a fatty diet, having had a vasectomy, exposure to certain environmental factors, and inheriting a a particular gene that also causes breast cancer • treatments include surgical removal, drugs, insertion of balloon into urethra, freezing of tumor, or insertion of a stent between lobes of prostate to relieve pressure on urethra 54 18 Clinical Application • Male infertility • Prostate cancer • Testicular cancer • Female infertility • Cervical cancer • Breast cancer 55 19 .