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The Reproductive System
• Gonads- Primary Sex Organs–Males - Testes–Females - Ovaries–Produce sex cells “gametes”•Males – sperm• Females – eggs
–Secrete sex hormones2
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
3
Testes
• Coverings of Testes– Tunica albuginea• White coat
surrounding each testes
– Septa• Divides testes
into a large number of lobules
5
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
6
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
7
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
8
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
9
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
10
Prostate Gland
• Encircles upper part of urethra• Secrets milky fluid that
activates sperm• Enters urethra through
several small ducts
11
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
12
Semen
• Milky white, somewhat sticky mixture of sperm and gland secretions• Provides transport, nutrients,
and chemicals that protect sperm and aid in movement
13
External Genitalia• Scrotum– 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 14
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
15
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 16
Spermatogenesis• Spermiogenesis–Maturing of
spermatids into sperm cells–3 regions of
mature sperm• Head – contains
DNA• Midpiece • Tail
• Entire process takes 64-72 days 18
Threats to Sperm Formation
• Penicillin• Tetracycline• Radiation• Lead• Certain pesticides• Marijuana• Tobacco• Excessive alcohol
20
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
Female Reproductive System
• Ovaries• Duct System–Uterine tubes (fallopian tubes)–Uterus–Vagina
• External Genitalia
23
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
26
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
27
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
29
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
30
Regions of the Uterus
• Body – main portion• Fundus – round region above
entrance of uterine tubes• Cervix – narrow outlet
protruding into vagina
32
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
33
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 34
External Genitalia• Mons pubis
– 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 35
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
36
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
37
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
38
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 40
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 43