Let

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Lets Talk About Sex.
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Chapter 16

• The Reproductive System

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I. Anatomy of the Male and Female Reproductive
System A. The primary sex organs, or gonads,
are the testis in males and the ovaries in
females. These organs produce gametes or sex
cells. For males, this is the sperm, for females
the ova or eggs. B. The Male Reproductive
System 1. Testes- olive sized male
reproductive organ which has both an exocrine
(sperm-producing) and an endocrine
(testosterone producing) function. The testes
contains seminiferous tubules which function as
sperm- forming factories. 2. Duct System
within the Testes includes the epididymis,
ductus deferens (vas deferens) and the
urethra. a. Epididymis- highly coiled tubes
found on the superior part of the testis. It
functions to mature and store sperm cells for
at least 20 days. It also expels sperm with
the contraction of the muscles in the
epididymis to the vas deferens.
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b. Ductus Deferens (Vas Deferens)- carries sperm
from the epididymis to the ejaculatory duct
which unites with the urethra. This passes over
the bladder and moves the sperm by peristalsis.
Many men will choose to have a vasectomy later in
life. This procedure involves cutting of the vas
deferens at the level of the testes to prevent
transportation of sperm. Sperm are still
produced but can no longer reach the exterior of
the body they simply deteriorate and are
absorbed by the body. c. Urethra- extends from
the base of the urinary bladder to the tip of the
penis. It carries BOTH sperm and urine. Sperm
will enter the urethra from the ejaculatory duct.
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3. Accessory glands and semen- a. seminal
vesicles- located at the base of the bladder
and produce a thick, yellowish secretion which
makes up 60 of semen. The fluids include
fructose (sugar), vitamin C, prostaglandins,
and other substances that nourish and activate
sperm. b. Prostate gland- encircles the upper
part of the urethra and secretes a milky fluid
that helps to activate sperm. This fluid
produced enters the urethra through small
ducts. The prostate tends to hypertrophy as men
age which strangles the urethra making
urination difficult.
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• c. Bulbourethral glands- pea-sized glands
  inferior to the prostate. This gland produces a
  thick, clear mucus that helps to cleanse the
  urethra of acidic urine. The mucus also serves
  as a lubricant during sexual intercourse.
• d. Semen- a mixture of sperm and accessory gland
  secretions. Fructose provides energy for the
  sperm cells, the alkalinity of semen helps
  neutralize the acidic environment of the vagina,
  and other elements of the semen enhance sperm
  motility.

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4. External Genitalia include the scrotum and
the penis a. Scrotum- a divided sac of skin
that hangs outside the abdominal
cavity. The scrotum provides the testes
with a temperature that is below body
temperature (about 3 degrees lower). b.
Penis- The penis is designed to deliver sperm
into the female reproductive tract. Regions of
the penis include the shaft, the glans penis
(enlarged tip) and the foreskin (prepuce). The
foreskin is usually surgically removed shortly
after birth by a procedure called
circumcision. -Internally the spongy urethra is
surrounded by three elongated areas of erectile
tissue, a spongy tissue that fills with blood
during sexual excitement.
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• 5. Spermatogenesis (sperm- production)- begins
  during puberty and continues throughout life.
  This process occurs in the seminiferous tubules.
  
• a. The process of spermatogenesis involves
  meiosis to produce haploid sperm cells. The
  process takes about 64 to 72 days.
• b. Sperm cells are the only flagellated cell in
  the human body. There are three regions the head
  (which contains the DNA and is covered with the
  acrosome containing enzymes that help the sperm
  penetrate the follicle cells surrounding the
  egg), midpiece and tail.
• c. The hormone FSH (follicle stimulating
  hormone) causes the production of sperm, and LH
  (Leutinizing Hormone) activates the testosterone
  producing cells.

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6. Testosterone Production- The most important
hormone produced in the interstitial cells of the
testes. a. Testosterone stimulates
reproductive organ development, underlies sex
drive, and causes secondary sex characteristics (
deepening of voice, increased hair growth,
thickening of bones, enlargement of skeletal
muscles.
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• C. The Female reproductive system
• Ovaries- the almond-sized primary female
  reproductive organs. Ovaries produce both an
  exocrine product (eggs or ova) and an endocrine
  product (estrogen and progesterone).
• a. Ovaries contain sac like structures called
  ovarian follicles. A follicle contains an oocyte
  (immature egg) surrounded by layers of follicular
  cells. Ovulation occurs when the matured egg is
  ready to be ejected from the ovary.
• 1) Suspensory ligaments secure the ovary to the
  wall of the pelvis, and the ovarian ligament
  secures the ovary to the uterus.

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• 2. Fallopian tubes- 4 inch long tubes extending
  medially from an ovary into the superior region
  of the uterus. They receive the ovulated oocyte
  and provide a site where fertilization can occur.
  
• a. The Fallopian tubes are not physically
  attached to the ovary. The fimbriae are the
  fingerlike projections at the distal end that
  receives the oocyte. Cilia inside the fallopian
  tube slowly move the oocyte towards the uterus
  (3-4 days). Fertilization occurs inside the
  fallopian tubes.

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1. Uterus- located between the urinary bladder and
   the rectum. In a woman that has never been
   pregnant it is about the size and shape of a
   pear. It is a hollow organ that receives,
   retains and nourishes the fertilized egg.
   Regions of the uterus include the body (major
   portion), the fundus (area where uterine tube
   enters) and the cervix (narrow outlet that
   protrudes into the vagina).

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• a. The wall of the uterus is thick and composed
  of three layers Endometrium- the inner layer
  that allows for implantation of a fertilized egg,
  is sloughed off if no pregnancy occurs. The
  myometrium is the bulky middle layer that is made
  of smooth muscle and plays an active role by
  contracting during the delivery of a baby. The
  outermost serous layer is the perimetrium or the
  visceral peritoneum.

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• 4. Vagina- extends from the cervix to the
  exterior of the body. The thin walled tube is 3
  to 4 inches long. It serves as the birth canal
  and for menstrual flow to leave the body. The
  distal end of the vagina is partially closed by a
  thin fold of mucosa called the hymen. The hymen
  may be ruptured during the first sexual
  intercourse or during a sports activity, or
  various other activities.

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5. External Genitalia, also called the vulva,
includes the mons pubis, labia, clitoris,
urethral and vaginal orifices. a. mons pubis-
fatty rounded area where pubic hair exists b.
labia- two delicate elongated hair-free folds of
skin c. clitoris- small protruding structure
that corresponds to the male penis. It is
hooded and composed of sensitive erectile tissue
that becomes swollen with blood during sexual
excitement. d. urethral orifice- is inferior
to the clitoris and superior to the vaginal
orifice.
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• 6. Oogenesis- the process of producing female
  gametes (eggs) using the process of meiosis.
• a. The total supply of eggs for a female are
  present at birth. The ability to produce eggs
  begins at puberty under the direction of
  hormones. A females reproductive ability
  declines and ends in a period called menopause.
• b. Primary oocytes are inactive until puberty.
  The hormone FSH (follicle-stimulating hormone)
  causes some primary follicles to mature. The LH
  hormone (leutinizing hormone), is responsible for
  causing ovulation (release of the egg from the
  ovary).
• c. Meiosis is completed after ovulation only if
  a sperm penetrates the egg.

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• 7. Hormone Production by the Ovaries
• Estrogen- produced by the growing and mature
  follicles, also cause the appearance of secondary
  sex characteristics in a young woman such as
  enlargement of accessory organs, breast
  development, Axillary and pubic hair, fat
  deposits in hips and breasts, widening of pelvis,
  onset of menstrual cycle.
• Progesterone- produced by a glandular structure
  of the ovaries called the corpus luteum (exists
  after ovulation). Progesterone production
  continues until LH diminishes in the blood. This
  hormone is very important in maintaining
  pregnancy. Many miscarriages are believed to be
  caused by declining levels of this hormone.

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II. Mammary Glands A. Mammary glands are
present in both sexes, but normally function
only in females. The role of these glands is to
produce milk to nourish a newborn baby. B.
The mammary glands are actually modified sweat
glands that are part of the skin. They are
stimulated by hormones (estrogen) to increase in
size C. Anatomy of the mammary gland 1.
Areola- central pigmented area of the breast 2.
Nipple- protruding central area of areola 3.
Lobes- internal structures that radiate around
nipple 4. Alveolar glands clusters of milk
producing glands within lobules 5.
Lactiferous ducts connect alveolar glands to
nipple III. Stages of Pregnancy and
Development A. Accomplishing Fertilization-
Sperm must make their way to the ovulated oocyte
in the fallopian tubes for fertilization to occur
(this journey to the egg usually takes 1-2
hours).
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1. The oocyte is viable for 12-24 hours after
ovulation 2. Sperm are viable for 12-48 hours
after ejaculation has occurred. a. Once
the sperm reach the oocyte their acrosomes
rupture, releasing enzymes that break down the
cement that holds the follicle cells
together around the egg B. Mechanisms of
Fertilization 1. Membrane receptors on an
oocyte pulls in the head of the first sperm cell
to make contact. The membrane of the oocyte does
not permit a second sperm head to enter. 2.
The oocyte then undergoes its second meiotic
division. 3. Fertilization occurs when the
genetic material of a sperm combines with that
of an oocyte to form a zygote. C. The Zygote 1.
The zygote is a result of the fusion of DNA from
the sperm and egg. 2. The zygote then
undergoes rapid mitotic cell division. This is
still occurring in the fallopian tubes as the
zygote continues to move towards the uterus.
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D. The Embryo 1. The developmental stage that
begins at cleavage (early stage of rapid cell
division). 2. The embryo enters the uterus at
the 16-cell stage. E. The Blastocyst Stage 1.
A ball-like circle of about 100 cells that begins
to secrete human chorionic gonadotropin (HCG) to
produce the corpus luteum to continue producing
hormones. HCG is the hormone that is detected in
a pregnancy test. 2. The late blastocyst
implants into the uterine wall by day 14. F.
Development after implantation 1. Projections
of the blastocyst called chorionic villi develop
which cooperate with the mothers uterine tissue
to form the placenta. 2. Once the placenta
has formed the embryo is surrounded by amnion (
a fluid-filled sac). The placenta functions to
form a barrier between the mother and the baby.
It delivers nutrients and oxygen to the embryo
and helps to remove wastes form the embryonic
blood. No blood is exchanged (see pages 349-350
to understand fetal circulation). The placenta
also becomes an endocrine organ taking over for
the corpus luteum and produces estrogen,
progesterone, and other hormones. 3. Finally
the umbilical chord forms to attach the embryo to
the placenta.
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G. The Fetus 1. All organ systems are formed
by the beginning of the eighth week. 2.
Activities of the fetus are growth and organ
specialization. H. Stages of Labor- Get this
baby out!! 1. Dilation- the cervix becomes
dilated, uterine contractions begin, the amnion
ruptures (water breaks) 2. Expulsion- infant
passes through the cervix and vagina, generally
head first. If the baby is breech (rear end
first) usually a c-section is needed. 3.
Placental stage- finally the last thing is the
delivery of the placenta- you can even cook and
eat the placenta because its full of nutrients.
Yummy!
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No SexMmm_K