Transcript Reproductive Systems

Reproductive Systems
Dr. Michael P. Gillespie
Sexual Reproduction
 Process by which organisms produce
offspring by making germ cells called
gametes.
 The male gamete (sperm cell) unites with the
female gamete (secondary oocyte). This is
called fertilization.
 The resulting cell contains one set of
chromosomes from each parent.
Reproductive Organs
 Males and females have anatomically distinct
reproductive organs that are adapted for
producing gametes, facilitating fertilization,
and in females sustaining the growth of the
embryo and fetus.
Reproductive Organs
 The male and female reproductive organs can
be grouped by function.
 Gonads – testes in males and ovaries in
females.
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Produce gametes and secrete sex hormones.
Reproductive Organs
 Ducts – store and transport gametes.
 Accessory sex glands – produces substances that
protect the gametes and facilitate movement.
 Supporting structures:
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Penis – facilitates delivery of gametes.
Uterus – facilitates delivery and joining of gametes.
Facilitates growth of fetus during pregnancy.
Gynecology
 Specialized branch of medicine concerned
with diagnosis and treatment of diseases of
the female reproductive system.
Urology
 The study of the urinary system.
 Urologists also diagnose and treat diseases of
the male reproductive system.
Number Of Chromosomes
 Human somatic cells contain 23 pairs of
chromosomes, or a total of 46 chromosomes.
 One member of each pair is inherited from
each parent.
 The members of each pair are called
homologous chromosomes or homologs.
They contain similar genes.
Number Of Chromosomes
 Most of the homologs look the same with the
exception of the sex chromosomes
(designated X & Y).
 Females carry to large X chromosomes.
Males carry one large X and one small Y
chromosome.
 The other 22 pairs of chromosomes are
called autosomes.
Number Of Chromosomes
 Somatic cells contain 2 sets of chromosomes,
so they are called diploid cells.
 Geneticists use the symbol n to denote the
number of different chromosomes in an
organism.
 In humans, n = 23. Diploid cells are 2n.
Meiosis
 The reproductive cell division that occurs in the
gonads.
 It produces gametes in which the number of
chromosomes is reduced by half.
 Gametes contain a single set of 23 chromosomes
and are called haploid cells.
 Fertilization restores the diploid number of
chromosomes.
Male Reproductive System
 The organs of the male reproductive system are the
testes, ducts, accessory sex glands, and supporting
structures including the scrotum and penis.
 The testes produce sperm and secrete hormones.
 A system of ducts transports and stores sperm.
 Semen contains sperm plus the secretions provided
by the accessory sex glands.
Functions Of The Male
Reproductive System
 Testes: produce sperm and the male sex hormone
testosterone.
 Ducts: transport, store, and assist in maturation of
sperm.
 Accessory sex glands: secrete most of the liquid
portion of the sperm.
 Penis: contains the urethra, a passageway for
ejaculation and the excretion of urine.
Scrotum
 The scrotum is the supporting structure for the
testes.
 Externally, the scrotum looks like a single pouch of
skin separated into lateral portions by a median
ridge of skin called the raphe.
 Internally, the scrotal septum separates the scrotum
into two sacs, each containing a single testis.
 The septum contains muscle tissue called the dartos
muscle.
Scrotum
 When the dartos muscle contracts, it wrinkles
the skin of the scrotum and elevates the
testes.
 The location of the scrotum and the
contraction of its muscle fibers regulate the
temperature of the testes.
Scrotum
 Normal sperm production requires a temperature
about 2-3 degrees C below core body temperature.
 The scrotum is outside of the pelvic cavity and
therefore maintains a lower temperature.
 The cremaster muscle elevates the testes upon
exposure to cold and during sexual arousal. This
moves the testes closer to the pelvic cavity, where
they can absorb body heat. The procedure is
reversed in response to warmth.
Testes
 The testes, or testicles, are paired oval
glands.
 A serous membrane called the tunica
vaginalis partially covers the testes.
Testes
 The tunica albuginea is internal to the
tunica vaginalis and divides the testes into
lobules.
 The lobules contain 200-300 seminiferous
tubules where sperm are produced.
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2 types of cells:
Spermatogenic cells – sperm forming cells.
 Sertoli cells – supporting cells.
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Testes
 Spermatogenesis is the process by which
sperm is produced.
 Leydig cells lie between the seminiferous
tubules and produce testosterone.
Cryptorchidism
 A condition in which the testes do not
descend into the scrotum.
 It occurs in about 3% of full-term infants and
30% of premature infants.
Cryptorchidism
 Untreated b/l cryptorchidism often results in
sterility due to high temperatures.
 The testes of about 80% of boys with
cryptorchidism descend spontaneously
within the 1st year of life.
 Untreated, it results in a greater chance of
testicular cancer.
Sperm
 Spermatogenesis produces about 300 million sperm
per day.
 Once ejaculated, most sperm do not survive more
than 48 hours in the female reproductive tract.
 The sperm consists of a head with an acrosome
(lysosomelike vesicle) and a nucleus with a haploid
# of chromosomes (23).
Sperm
 Enzymes within the acrosome aid in
penetration of the sperm cell into the
secondary oocyte.
 The midpiece contains mitochondria.
 The tail is a typical flagellum that propels the
sperm cell.
Hormonal Control Of The
Testes
 Gonadotropin-releasing hormone (GnRH) – at
puberty, the hypothalamus begins to release this
hormone, which stimulates the release of luteinizing
hormone (LH) and follicle-stimulating hormone
(FSH).
 LH stimulates Leydig cells to secrete testosterone.
 FSH and testosterone stimulate spermatogenesis.
Ducts Of The Testis
 Pressure generated by the fluid secreted by
Sertoli cells pushes sperm and fluid along the
lumen of the seminiferous tubules into the
straight tubules.
 The straight tubules lead to the rete testis
and then into the efferent ducts. The
efferent ducts empty into the ductus
epididymis.
Epididymis
 The epididymis is a comma-shaped organ that lies
along the posterior border of each testis.
 The ductus epididymis is the site where the sperm
mature.
 Sperm are stored here and peristaltic contraction
propels them into the ductus (vas) deferens.
 Sperm may remain here for a month or more.
Ductus Deferens
 Within the tail of the epididymis, the ductus
becomes less convoluted and is known as the
ductus deferens or vas deferens.
 Functionally, the ductus deferens stores sperm and
conveys them toward the urethra by peristaltic
contractions of the muscular coat.
 Sperm that are not ejaculated are eventually
reabsorbed.
Spermatic Cord
 The spermatic cord is a supporting structure
of the male reproductive system that ascends
out of the scrotum.
 The spermatic cord passes through the
inguinal canal into the abdomen.
Spermatic Cord
 The canal originates at the deep (abdominal)
inguinal ring, a slitlike opening in the
aponeurosis of the transversus abdominis
muscle.
 The canal ends at the superficial
(subcutaneous) inguinal ring, an opening in
the aponeurosis of the external oblique
muscle.
Inguinal Hernias
 The inguinal region is a weak area in the
abdominal wall.
 Consequently, it is often the site of an
inguinal hernia – a rupture or separation of a
portion of the inguinal area of the abdominal
wall.
Inguinal Hernias
 Indirect inguinal hernia – part of the small
intestine protrudes through the deep inguinal
ring and enters the scrotum.
 Direct inguinal hernia – a portion of the
small intestine pushes into the posterior wall
of the inguinal canal causing a localized
bulging in the wall of the canal.
Ejaculatory Ducts
 The ejaculatory ducts are formed by the
union of the duct from the seminal vesicle
and the ampulla of the ductus deferens.
 They eject sperm and seminal vesicle
secretions into the urethra just before
ejaculation (propulsion of semen from the
urethra to the exterior).
Urethra
 In males, the urethra is the shared terminal
duct of the reproductive and urinary systems.
Accessory Sex Glands
 The accessory sex glands secrete most of the
liquid portion of the semen.
 They include the seminal vesicles, the
prostate, and the bulbourethral glands.
Functions Of The Accessory
Sex Gland Secretions
 Seminal vesicles – secrete alkaline, viscous
fluid that helps neutralize the acid secretions
of the female reproductive tract. Provides
fructose for ATP production by sperm.
Contributes to sperm motility, viability, and
helps semen coagulate after ejaculation.
Functions Of The Accessory
Sex Gland Secretions
 Prostate – secretes a milky, slightly acidic fluid that
helps semen coagulate after ejaculation and
subsequently breaks down the clot.
 Bulbourethral (Cowper’s) glands – secrete alkaline
to neutralize the acidic environment of the urethra
and mucous to lubricate the lining of the urethra
and tip of the penis during intercourse.
Semen
 Semen is a mixture of sperm and seminal
fluid, a liquid that consists of the secretions
of the seminiferous tubules, seminal vesicles,
prostate, and bulbourethral glands.
 Semen has a slightly alkaline ph of 7.2 – 7.7.
Semen
 The prostatic secretions give the fluid a
milky appearance, whereas fluids from the
seminal vesicles and bulbourethral glands
give it a sticky consistency.
 Seminal fluid provides sperm with a
transportation medium, nutrients, and
neutralizes the hostile acidic environment of
the male urethra and female vagina.
Penis
 The penis contains the urethra and is a passageway
for the ejaculation of semen and the secretion of
urine.
 It is cylindrical in shape and consists of a root,
body, and glans penis.
 Root of the penis is the attached (proximal) portion.
It consists of the following:
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Bulb of the penis (expanded portion of the base).
Crura of the penis (the 2 separated and tapered portions).
Penis
 Body of the penis.
 Glans of the penis – a slightly enlarged,
acorn-shaped region (distal region).
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The prepuce (foreskin) covers the glans in an
uncircumcised penis.
The fundiform ligament and the suspensory
ligament of the penis arise from the pubic
symphisis and support the weight of the penis.
Erection
 Upon sexual stimulation, the arteries
supplying the penis dilate and large
quantities of blood enter the sinuses.
 The stimulation may be visual, tactile,
auditory, olfactory, or imagined.
Erection
 Expansion of these spaces compresses the veins
draining the penis, so blood outflow is slowed.
 These vascular changes are due to the local release
of nitric oxide and a parasympathetic reflex and
result in an erection (the enlargement and stiffening
of the penis).
 Return to a flaccid state occurs when the arteries
constrict and pressure on the veins is relieved.
Ejaculation
 Ejaculation is a sympathetic reflex.
 The smooth muscle sphincter at the base of
the urinary bladder closes; Therefore, urine is
not expelled during ejaculation and semen
does not enter the urinary bladder.
Ejaculation
 Before ejaculation occurs, peristaltic
contractions occur and propel semen into the
penile portion of the urethra. This leads to
emission, the discharge of a small volume of
semen before ejaculation.
 Emission may also occur during sleep
(nocturnal emission).
Circumcision
 Circumcision is a surgical procedure in which part
or the entire prepuce is removed.
 It is usually performed just after delivery, 3 to 4
days after birth, or on the 8th day as part of a Jewish
religious rite.
 The following benefits may result from
circumcision: lower risk of urinary tract infections,
protection against penile cancer, and possibly a
lower risk of STDs.
Organs Of The Female
Reproductive System
 Ovaries
 Uterine (Fallopian) tubes {oviducts}
 Uterus
 Vagina
 External organs
Functions Of The Female
Reproductive System
 Ovaries – produce secondary oocytes and
hormones (progesterone, estrogens, inhibin,
& relaxin).
 Uterine tubes – transport a secondary oocyte
to the uterus and normally are the sites where
fertilization occurs.
Functions Of The Female
Reproductive System
 Uterus – site of implantation of a fertilized
ovum, development of the fetus during
pregnancy, and labor.
 Vagina – receives the penis during sexual
intercourse and is a passageway for
childbirth.
 Mammary glands – synthesize, secrete, and
eject milk for nourishment of the newborn.
Ovaries
 The female gonads are the 2 ovaries.
 They lie on either side of the uterus.
 They produce the gametes that develop into
mature ova (eggs) after fertilization.
 They produce the hormones progesterone,
estrogens (female sex hormones), inhibin,
and relaxin.
Supporting Ligaments Of The
Ovaries
 Broad ligament of the uterus attaches to the
ovaries and holds them in position.
 Ovarian ligament anchors the ovaries to the
uterus.
 Suspensory ligament attaches the ovaries to
the pelvic wall.
Uterine Tubes
 Females have two uterine (fallopian) tubes, or
oviducts that extend laterally from the uterus.
 They provide a route for the sperm to reach an
ovum and transport secondary oocytes and
fertilized ova from the ovaries to the uterus.
 Local currents produced by movements of the
fimbriae (fingerlike projections) sweep the ovulated
secondary oocyte from the pelvic cavity into the
uterine tube.
Fertilization
 A sperm usually encounters and fertilizes a
secondary oocyte in the ampulla of the
uterine tube.
 Fertilization can occur at anytime within 24
hours after ovulation.
Fertilization
 After fertilization, the nuclear materials of
the haploid ovum and sperm unite.
 The diploid fertilized ovum is called a zygote
and begins to undergo cell divisions while
moving toward the uterus.
 It arrives at the uterus 6 to 7 days after
ovulation.
Uterus
 The uterus (womb) serves as part of the pathway
for sperm deposited in the vagina to reach the
uterine tubes.
 It is the site of implantation of a fertilized ovum,
development of the fetus during pregnancy, and
labor.
 During reproductive cycles when impantation does
not occur, the uterus is the source of menstrual
flow.
Anatomy Of The Uterus
 Anatomical divisions of the uterus include:
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Fundus – a dome shaped portion superior to the uterine
tubes.
Body – a tapering central portion. The uterine cavity
lies in here.
Cervix – an inferior narrowing portion that opens into
the vagina. The interior is called the cervical canal. It
opens into the uterine cavity at the internal os and into
the vagina at the external os.
 The isthmus is the portion between the body and the
cervix.
Anatomy Of The Uterus
 Anteflexion - normally, the body of the uterus
projects anteriorly and superiorly over the urinary
bladder.
 Retroflexion – A posterior tilting of the uterus.
 The uterosacral ligaments, cardianl (lateral cervical)
ligaments, and round ligaments normally hold the
uterus in anteflexion, but can permit enough
movement for the uterus to become malpositioned.
Uterine Prolapse
 Uterine prolapse is a falling down or
downward displacement of the uterus.
 This condition may result from weakening of
supporting ligaments and pelvic musculature.
Uterine Prolapse
 This is associated with disease, traumatic
vaginal delivery, chronic straining from
coughing or difficult bowel movements, or
pelvic tumors.
Uterine Prolapse
 Degrees of prolapse:
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1st degree (mild) – the cervix remains within the
vagina,
2nd degree (marked) – the cervix protrudes to the
exterior through the vagina.
3rd degree (complete) – the entire uterus is
outside the vagina.
Uterine Prolapse
 Treatment varies depending upon the degree of
prolapse:
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Pelvic exercise.
Dieting if the patient is overweight.
A stool softener to minimize straining during defecation.
Pessary therapy – placement of a rubber device around
the uterine cervix to prop up the uterus.
Surgery.
Hysterectomy
 Hysterectomy is the surgical removal of the uterus.
 It is the most common gynecological operation.
 It may be indicated in conditions such as
endometriosis, pelvic inflammatory diseases,
recurrent ovarian cysts, excessive uterine bleeding,
and cancer of the cervix, uterus, or ovaries.
Vagina
 The vagina is a tubular, long fibromuscular
canal lined with mucous membrane that
extends from the exterior of the body to the
uterine cervix.
 It is the receptacle for the penis during sexual
intercourse, the outlet for menstrual flow,
and the passageway for childbirth.
Vagina
 It has an acidic environment that retards microbial
growth, but is also harmful to sperm.
 Hymen – a thin fold of vascularized mucous
membrane closes the inferior end of the vaginal
opening to the exterior (vaginal oriface).
 Imperforate hymen – sometimes the hymen
completely covers the oriface. Surgery may need to
be performed to permit the discharge of menstrual
flow.
Vulva
 Vulvu or pudendum refer to the external
genitals of the female.
Vulva Components
 Mons pubis – elevation of adipose tissue covered
by skin and coarse pubic hair that cushions the
pubic symphysis.
 Labia majora.
 Labia minora.
 Clitoris – a cylindrical mass of erectile tissue and
nerves.
 Prepuce of the clitoris.
Vulva Components
 Vestibule.
 Vaginal oriface.
 External urethral oriface.
 Paraurethral (Skene’s) glands – mucous
secreting glands.
 Greater vestibular (Bartholin’s) glands –
mucous secreting glands.
Perineum
 The perineum is a diamond-shaped area medial to
the thighs and bottocks of both males and females,
 It contains the external genitals and anus.
 It is bounded on the anterior by the pubic
symphisis, laterally by the ischial tuberosities, and
on the posterior by the coccyx.
 The anterior urogenital triangle contains the
external genitals and the posterior anal triangle
contains the anus.
Episiotomy
 During childbirth, the emerging fetus
stretches the perineal region.
 A physician sometimes performs an
episiotomy, a perineal cut made with surgical
scissors.
Episiotomy
 The cut enlarges the vaginal opening to make
more room for the fetus to pass.
 The straight cut is easier to suture than the
jagged tear that may form naturally.
 The incisions is closed in layers with a suture
that is absorbed. Stitches do not need to be
removed.
Mammary Glands
 The 2 mammary glands are modified
sudoriferous (sweat) glands that produce
milk.
 Each breast has a nipple with lactiferous
ducts where milk emerges.
Mammary Glands
 The areola is the area surrounding the nipple
and contains sebacous (oil) glands.
 The suspensory ligaments of the breast
(cooper’s ligaments) support the breast
tissue.
 The functions of the mammary glands are the
synthesis, secretion, and ejection of milk
(lactation).
Fibrocystic Disease Of The
Breasts
 The breasts of females are highly susceptible
to cysts and tumors.
 Frbrocystic disease is the most common
cause of breast lumps in females.
Fibrocystic Disease Of The
Breasts
 Cysts (fluid filled sacs) develop.
 Mainly in females between ages 30 and 50
due to excess of estrogens or deficiency of
progesterone.
 This occurs about a week or so before
menstruation begins.