The Reproductive System Chapter 16
The Reproductive System Gonads- Primary Sex Organs Males - Testes Females - Ovaries Produce sex cells “gametes” Males – sperm Females – eggs Secrete sex hormones
Male Reproductive System Testes Duct System Epididymis Ductus Deferens Urethra Accessory Glands and Semen Seminal vesicles Prostate gland Bulbourethral Glands Semen External Genitalia Scrotum Penis
Male Reproductive System
Testes Coverings of Testes Tunica albuginea Septa White coat surrounding each testes Septa Divides testes into a large number of lobules
Testes Each lobule contains one of four tightly coiled seminiferous tubules “sperm-forming factories” Empty sperm into rete testis Sperm travels through rete testis to epididymis Intersitial cells produce horomones More specifically testosterone
Epididymis Comma shaped highly coiled tube Provides storage site for immature sperm that enter testis Sperm mature while in epididymis over 20 days When sexually stimulated- walls contract to expel sperm to ductus deferens
Ductus Deferens (vas deferens) Propels live sperm from epididymis to urethra by perisalisis End of ductus deferens empties into ejaculatory duct Spermatic cord- ductus deferense, blood vessels and nerves Vasectomy – cutting of ductus deferense – leads to sterility but no loss in sex drive
Urethra Extends from base of urinary blader to tip of penis 3 regions Prostatic urethra – surrounded by prostate gland Membranous urethra – distance from prostatic urethra to penis Spongy (penile) urethra – runs within length of penis Carries both urine and sperm Never pass at the same time
Seminal Vesicles At base of bladder Produce about 60% of fluid volume of semen Thick yellowish secretion rich in sugar, vitamin C, prostaglandins and other substances Nourish and activate the sperm
Prostate Gland Encircles upper part of urethra Secrets milky fluid that activates sperm Enters urethra through several small ducts
Bulbourethral Glands Produce thick, clear mucus that drains into penile urethra First secretion to pass when man become sexually excited Cleans out traces of acidic urine Serves as lubricant for sexual intercourse
Semen Milky white, somewhat sticky mixture of sperm and gland secretions Provides transport, nutrients, and chemicals that protect sperm and aid in movement
External Genitalia Scrotum Penis Sac of skin hanging outside abdominal cavity Provides temperature about 30 C lower than body temp for healthy sperm Penis Delivers sperm to female reproductive tract Regions of the penis Shaft Glans penis – enlarged tip Prepuce or foreskin – cuff of skin Can be removed in circumcision Erection – spongy urethra that fills with blood during sexual excitement
Spermatogenesis Production of sperm Starts during puberty and continues throughout life Every day man makes millions of sperm Sperm formation takes place in seminiferous tubules of testis
Spermatogenesis Spermatogonia Rapid mitoic divison to build up stem cell line Follicle-stimulating hormone modifies division Division produces two types of cells One stem cell Primary spermatocyte
Spermatogenesis Primary spermatocytes undergo meiosis Produce four sperm – spermatids
Spermatogenesis Spermiogenesis Entire process takes 64-72 days Maturing of spermatids into sperm cells 3 regions of mature sperm Head – contains DNA Midpiece Tail Entire process takes 64-72 days
Anatomy of a Mature Sperm DNA is found in head Only flagellated cell in human body
Threats to Sperm Formation Penicillin Tetracycline Radiation Lead Certain pesticides Marijuana Tobacco Excessive alcohol
Testosterone Production Produced in testes in intersitial cells Stimulates reproductive organ development Underlies sex drive Causes secondary male sex characteristics Deepening of voice Increased hair growth Enlargement of skeletal muscles Increased heaviness of skeleton
21 slides 6 picture only slides 2 picture and word slides 13 word slides
Female Reproductive System Ovaries Duct System Uterine tubes (fallopian tubes) Uterus Vagina External Genitalia
Female Reproductive System
Ovaries Primary reproductive organ Ovarian follicles Sac like structures Oocyte Follicle cells
Ovarian Follicle Stage Primary follicle- contains immature oocyte Graafian follicle- enlargement of follicle and maturation of oocyte Ovulation- rupturing of follicle and ejection of developed egg Occurs about every 28 days Corpus luteum- transformed ruptured follicle
Support for Ovaries Suspensory ligaments – secure ovaries to lateral walls of pelvis Ovarian ligaments – anchor ovaries to uterus Broad ligaments – enclose and hold ovaries in place by a fold of peritoneum
Support for the Ovaries
Uterine Fallopian Tubes Initial part of duct system Provide site where fertilization can occur Does not connect to uterine tubes and ovaries End of tube has fimbriae – fingerlike projections Held in place by broad ligament Move oocyte toward uterus (3-4 days) by peristalsis and rythmic beating of cilia
Uterus Located between urinary bladder and rectum Receives, retains and nourishes a fertilized egg Size and shape of pear in unpregnant woman Suspended in pelvis by broad ligament and anchored by round and uterosacral ligaments
Support for the Uterus
Regions of the Uterus Body – main portion Fundus – round region above entrance of uterine tubes Cervix – narrow outlet protruding into vagina
Walls of the Uterus Endometrium Inner layer Where fertilized egg resides during development Sloughs off about every28 days (menses) if not pregnant Myometrium – middle layer of smooth muscle Active role during delivery Visceral peritoneum – outermoust serous layer
Vagina Thin-walled tube Extends from cervix to body exterior Also known as birth canal Receives penis and semen during sexual intercourse Hymen is distal end of vagina and usually ruptures during first sexual intercourse
External Genitalia Mons pubis Labia – skin folds Vestibule Clitoris Fatty, rounded area over pubic area Usually covered with pubic hair Labia – skin folds Labia majora Labia minora Vestibule Contains external opening of urethra Greater vestibular glands- provide lubrication during intercourse Clitoris Composed of erectile tissue similar to penis
Oogenesis Total supply of eggs is determined by birth Reproductive ability begins at puberty and ends around 50s (menopause) Similar to formation of sperm in male testes
Oogenesis Oogonia – female stem cells found in a developing fetus Mitosis occurs to produce primary oocytes Primary oocytes surrounded by single layer of cells to form primary follicles Oogonia does not exist after birth Primary oocytes inactive until puberty
Oogenesis Follicle-stimulating hormone released during puberty causing some primary follicles to mature Meiosis starts inside maturing follicle Produces seconday oocyte and first polar body is formed Meiosis finishes only if sperm penetrates and fertilization occurs Two more polar bodies are formed
Menstrual Cycle Cyclic changes of endometrium Controlled by cyclic production of estrogen and progesterone by ovaries Stages of the menstrual cycle Menses Day 1-5: functional layer of endometrium is sloughed off Accompanied by 3 – 5 days of bleeding Proliferative stage Day 6 – 14: regeneration of endometrium layer Secretory stage Day 15 – 28: endometrium increases in size and becomes ready for implantation
Hormone Control of Ovarian and Uterine Cycles
Hormone Control of Ovarian and Uterine Cycles
Hormone Production of the Ovaries Estrogens Produced by follicle cells Causes appearance of secondary characteristics Enlargement of accessory organs Development of breasts Appearance of pubic and axillary hair Increased deposits of fats in hips and breasts Widening and lightening of pelvis Onset of menses (menstrual cycle) Progesterone Produced by corpus luteum Produced as long as LH is present Helps maintain pregnancy
Mammary Glands
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System
Male Reproductive System