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Reproductive System. Ch 27. Difference between Meiosis and Mitosis. Meiosis I. Interphase. Prophase I. Metaphase I. Anaphase I. Telephase I. Meiosis II. Prophase II. Metaphase II. Anaphase II. Telephase II. Male Reproductive System.
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Reproductive System Ch 27
Meiosis I Interphase Prophase I Metaphase I Anaphase I Telephase I
Meiosis II Prophase II Metaphase II Anaphase II Telephase II
Human reproduction involves intricate anatomy and complex behavior Reproductive Anatomy of the Human Male. • External: - penis - scrotum • Internal: - gonads - accessory sex glands and ducts.
External structure of the penis: • glans penis • prepuce (foreskin) • There is no verifiable health benefit to circumcision.
sutures shaft corona foreskin glans penis urethral opening Circumcision
The penis is composed of three layers of spongy erectile tissue. • During sexual arousal the erectile tissue fills with blood from arteries. • The resultant increased pressure seals off the veins that drain the penis. • The engorgement of the penis with blood causes an erection. urethra
Testes are the male gonads. • seminiferous tubules- form sperm • Leydig cells (interstitial cells)- produce androgens (ex. Testosterone, ABP).
Testes are located in the scrotum, outside the body cavity. • This keeps testicular temperature cooler than the body cavity. • The testes develop in the body cavity and descend into the scrotum just before birth.
Sperm Pathway Membranous urethra Prostatic urethra
Semen • Seminal fluid is thick, yellowish, and alkaline. • It contains mucus, fructose, a coagulating enzyme, ascorbic acid, and prostaglandins. • Accessory glands: • seminal vesicle • prostate gland • bulbourethral gland
Seminal vesicle: • A pair of glands that secrete a liquid component of semen into the vas deferens. • Secretion is alkaline • Contains fructose, asorbic acid, coagulating enzyme, prostaglandin Seminal Vesicle
Prostate gland: • Location- surrounds and opens into the urethra where it leaves the bladder. • Secretion- slightly alkaline fluid that activates the sperm and prevents them from sticking together • Prostate problems are common in males over 40. • Prostate cancer is one of the most common cancers in men. Prostate
Bulbourethral gland (Cowper’s gland): • Location- paired glands that lie beneath the prostate • Secretion- a thick, clear alkaline mucous that drains into the membranous urethra. • Function- It acts to wash residual urine out of the urethra when ejaculating semen-- raises pH; neutralizes acidity of urine. Bulbourethral gland
Ejaculation • Ejaculation propels sperm from the epididymis to the vas deferens. • The vas deferens run from the scrotum and behind the urinary bladder. • Here each vas deferens joins with a duct from the seminal vesicle to form an ejaculatory duct. • The ejaculatory ducts open into the urethra. • The urethra drains both the excretory and reproductive systems.
Ejaculate • A male usually ejaculates about 2 – 5 mL of semen; each milliliter containing about 50 – 130 million sperm. • Bulbourethral fluid also carries some sperm released before ejaculation. • This is one of the reasons why the withdrawal method of birth control has a high failure rate.
Mature Spermatozoa acrosome head nucleus tail mitochondria
Seminiferous Tubules Spermatids Spermatozoa Sertoli/ sustenacular cell 2º spermatocyte 1º spermatocyte spermatogonium Interstitial cells
Hormones Involved in Spermatogenesis • Gonadotropin Releasing Hormone (GnRH) • Follicle Stimulating Hormone (FSH) • Interstitial Cell Stimulating Hormone (ICSH=LH) • Testosterone • Inhibin • ABP
Hormonal Control of Spermatogenesis Hypothalamus GnRH Anterior Pituitary ICSH FSH
Hormonal Control of Spermatogenesis ICSH Interstitial Cells Testosterone
Hormonal Control of Spermatogenesis FSH Testosterone Sertoli Cells Inhibin Spermatogenesis
Hormonal Control of Spermatogenesis Feedback Inhibition Inhibin Acts on anterior pituitary Inhibits FSH production Testosterone Acts on hypothalamus Inhibits GnRH production
Some Other Effects of Testosterone • muscle and bone growth • facial and pubic hair growth • thickening of vocal cords • growth of pharyngeal cartilage • hair follicle effects • stimulates sebaceous glands • Increased BMR
Female Reproductive System uterine tube Ovary uterus cervix Bladder vagina clitoris urethra l. majora l. minora
Internal reproductive: • Vagina • Cervix • Fallopian tube (uterian tube/oviducts) • Fimbrae • Ovary • Uterus • Endometrium • Myometrium • Perimetrium uterus uterine tube ovary endometrium fimbriae myometrium perimetrium cervix vagina
Oogenesis • Ovary- contains 400,000 oocytes; release about 500 in a lifetime • Ovary- under influence of FSH. The follicles mature every 28 days • Primary follicle produces estrogens • And primary oocyte completes its 1st division produces 2ndary oocyte and polar body
Oogenesis • Aprox 1/2 way through the 28 day cycle the follicle reaches the mature Vesticular or Graffian follicle stage.
Oogenesis • Estrogen levels rise and release LH and FSH and triggers ovulation.
Oogenesis • The 2ndary oocyte travels down the uterine tube to the uterus. • If fertilized by sperm, it will produce a zygote Ovum in uterine tube
Hormones Involved in the Female Reproductive Cycle • Gonadotropin Releasing Hormone (GnRH) • Follicle Stimulating Hormone (FSH) • Luteinizing Hormone (LH) • Estrogen • Progesterone • Inhibin • Relaxin
Female Hormonal Cycle Hypothalamus GnRH Anterior Pituitary LH FSH