Human Reproduction and Development Anatomy of the Male and
Female Reproductive Systems Gamete Formation Hormonal Control of
Reproduction Conception, Pregnancy, Development, Birth
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Male Anatomy External genitalia Penis and Scrotum Internal
Reproductive Organs Pair of gonads Produce gametes (sperm cells)
Produce hormones Accessory glands Secret products essential to
sperm movement Set of ducts Carry sperm and glandular
secretions.
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Male Anatomy Penis Composed of 3 cylinders of spongy tissue.
During sexual arousal, tissue fills with blood from the arteries
The increasing pressure seals off the veins that drain the penis
Result = penis engorges with blood = erection The tip (Glans) is
covered by a fold of skin called the foreskin, which may be removed
by circumcision A tradition with religious roots. No verifiable
health or hygienic advantage.
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Male Anatomy Scrotum Sac which contains testes Regulates
temperature of testes by contraction of cremaster muscle. Cold =
contracts Brings testes close to body to warm up. Warm = relaxes
Goal = keep testes 3 o below normal body temperature.
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Male Anatomy Testes Stored in scrotum Before birth, testes
develop in the abdomen and then migrate down a canal into scrotum
around the time of birth. Sperm producing organ Made in tightly
coiled tubes called seminiferous tubules inside testes Sperm
produced is not fully mature when it leaves testis (not motile yet)
Source of male hormone testosterone Made by interstitial cells
scattered between the seminiferous tubules Deposits sperm into
epididymis
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Male Anatomy Epididymis Coiled tubes About 6 meters long!!
Posterior to the testis Stores sperm Site of further sperm
maturation Gains motility Contracts during ejaculation, expelling
sperm into vas deferens Sperm can be store here for months If not
ejaculated, will eventually be phagocytized
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Male Anatomy Vas Deferens Muscular tubes that carry sperm from
epididymis to ejaculatory duct (and eventually the urethra)
peristalsis Urethra drains both the excretory system and the
reproductive system Not the case in females
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Male Anatomy Ejaculatory Duct Connects seminal vesicle to
urethra Passes through prostate gland
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Male Anatomy Seminal Vesicle Lies below and behind bladder
Secretes thick, clear fluid into ejaculatory duct 60% volume of
semen (the fluid that is ejaculated) Alkaline to neutralize acidic
pH of vagina Fructose used for energy by sperm Prostaglandins
chemical messengers which, once in female, stimulate uterine
peristalsis to help move semen up the uterus Proteins cause semen
to coagulate after it is deposited in the female, making it easier
for the uterine contractions to move the semen
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Male Anatomy Prostate Gland Doughnut shaped gland which
surrounds urethra Secretes thin milky fluid into urethra 20% of
seminal volume Liquefy the semen prevents sperm from clumping
together Alkaline continues to neutralize acid from residual urine
in urethra and natural acidity of vagina
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Male Anatomy Cowpers Gland (Bulbourethral Gland) Pair of small
glands along urethra, below the prostate Secrete viscous fluid
before emission of sperm & semen Thought to lubricate penis and
vagina Released before ejaculation Fluid does contain some sperm
One factor in the high failure rate of the withdrawal method of
birth control.
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Male Anatomy Vasectomy Incision through scrotum Cut and tie off
vas deferens Sperm is still produced but cant get out
Phagocytized
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Male Anatomy Review Passageway from testes to outside
1.Multiple seminiferous tubules site of spermatogenesis 2.Single
tubed epididymis 3.Vas deferens 4.Seminal vesicle 5.Ejaculatory
duct 6.Urethra
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Fun Facts For Your Information Volume of ejaculation = 2.75 ml
pH = 7.2 7.6 50 150 million sperm per ml. Only a few sperm reach
the egg Average sperm count has decreased from 113 million/ml to 66
million/ml in past 40 years. Infertility =
Hormonal Control Male Reproductive System Control Testosterone
Primary Function Stimulate spermatogenesis Secondary Function
Maturation of testes and penis Sex drive Facial hair Body hair
Deeper voice Increased muscle strength Body oil secretion --
acne
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Hormonal Control Hypothalamus releases 1.Gonadotropin-Releasing
Hormone (GnRH) Stimulates pituitary to release LH & FSH
Pituitary releases 1.Follicle-Stimulating Hormone (FSH) Stimulates
spermatogenesis by seminiferous tubules 2.Luteinizing hormone (LH)
Stimulates testosterone production by interstitial cells Indirectly
stimulates spermatogenesis because testosterone is required for
sperm production.
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Hormonal Control LH, FSH, and GnRH concentrations in the blood
are controlled by negative feedback systems
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Testosterone production Spermatogenesis
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Testosterone production Spermatogenesis
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Hormonal Control
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Female Anatomy External genitalia - Two sets of labia that
surround the clitoris and vaginal opening Internal Reproductive
Organs -A pair of gonads (ovaries) -A system of ducts and chambers
to -Conduct the gametes -House the embryo and fetus
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Internal Organs
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Female Anatomy Ovaries Lie in abdomen, below most of the
digestive system Enclosed in a tough protective capsule Produces
eggs (follicles) Produces female sex hormones 1.Estrogen
2.Progesterone
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Female Anatomy
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Follicles Consists of one egg cell surrounded by layers of
follicle cells. Nourish and protect the developing egg cell All of
the 400,000 follicles a woman will ever have are present at birth.
Only a few hundred will be released during a womans reproductive
years One (very rarely 2 or more) follicle matures and releases its
egg during each menstrual cycle
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Female Anatomy Follicles Follicle cells release the primary
female sex hormone estrogen. Secondary sex characteristics, wider
hips, more body fat, Necessary for breast development At ovulation,
the egg explodes out of the follicle leaving behind the follicular
tissue This grows into a solid mass called a Corpus Luteum Secretes
progesterone (necessary for pregnancy) If fertilization does not
occur, the corpus luteum disintegrates and a new follicle matures
the next month.
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Female Anatomy Oviduct Fallopian tube Conducts eggs to the
uterus Fertilization occurs here If embryo grows here = ectopic
pregnancy The ovary and oviduct dont actually touch. The egg is
released into the abdominal cavity and is sucked into the oviduct.
Oviduct has fingers called fimbrae and hairs called cilia that
vibrate and sweep the egg into the tube by swishing body fluids
towards itself These cilia also help move the egg towards the
uterus
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Female Anatomy
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Uterus (womb) Houses and nurtures the developing fetus Oviducts
enter at the top Cervix (opening) at the bottom The lining is
called the endometrium Richly supplied with blood vessels Varies in
thickness depending on the stage of the menstrual cycle Controlled
by hormones 2 Layers Basal layer = stable, does not change
thickness Functional layer = changes thickness with
menstruation
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Female Anatomy
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Vagina Birth canal Average = 7.5 cm in length pH = 4-5 Upper
end closes at cervix Receives penis during sexual intercourse
Elastic to facilitate sexual intercourse and birth
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Female Anatomy
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Gametogenesis 1. The walls of the seminiferous tubules consist
of diploid spermatogonia, stem cells that are the precursors of
sperm. 2. divide by mitosis to produce more spermatogonia 3. The
Meiosis of each spermatocyte produces 4 haploid spermatids. 4.
These then differentiate into sperm, losing most of their cytoplasm
and gaining motility in the process. In epididymis Sperm nourished
by sertoli cells (in seminiferous tubules) Sperm nourished by
sertoli cells (in seminiferous tubules) Whole process takes 70 days
Whole process takes 70 days
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Gametogenesis 1. Takes place in ovaries 2. Primary Oogonium
develop into oocytes before birth 3. Oocytes complete maturation
one at a time & once a month during reproductive years 4.
Primary oocyte grows larger and begins meiosis 5. Forms a secondary
oocyte and first polar body 6. After fertilization, secondary
oocyte completes meiosis and become 1 egg and second polar
body.
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Hormonal Control Hypothalamus - produces releasing GnRH
Anterior Pituitary secrete gonadotropic hormones. FSH - follicle
stimulating hormone. LH - luteinizing hormone. Ovaries - secrete
the female sex hormones. Estrogen thickening of uterine lining
Progesterone matures/maintains uterine lining
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Hormonal Control FSH is released from AP Start the ripening of
ovum within follicle Estrogen is produced by follicle Development
of endometrium for possible pregnancy Feedback to hypothalamus to
inhibit FSH and release LH
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Hormonal Control LH surge on day 14 Stimulates ovulation
Conversion of follicle into corpus luteum Progesterone production
Continued development of endometrium Feedback to inhibit release of
LH
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Hormonal Control If no fertilization Degeneration of corpus
luteum Drop in hormone level
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The 4 Phases of Menstruation
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Female Anatomy sdfsdfsdf
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Menstruation 1.Flow Phase (Menstrual Phase) Start of bleeding
marks Day 1 of phase Shedding of the endometrium (uterine lining)
Average = 4-5 days Sometimes up to 8 days Occurs due to low hormone
levels
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Female Anatomy sdfsdfsdf 1
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Menstruation 2.Follicular Phase Occurs during day 6-13 Period
of repair and thickening of endometrium.
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Female Anatomy sdfsdfsdf
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Menstruation 2.Follicular Phase Occurs during day 6-13 Period
of repair and thickening of endometrium. FSH from the pituitary
promotes follicle development in the ovary.
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Female Anatomy sdfsdfsdf
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Menstruation 2.Follicular Phase Occurs during day 6-13 Period
of repair and thickening of endometrium. WHY?? FSH from the
pituitary promotes follicle development in the ovary. As follicle
develops it produces estrogen, thickening of the uterine lining LH
production increase FSH production decrease
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Menstruation FSHDecrease
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3.Ovulation Phase LH causes ovulation to occur on day 14.
Secondary oocyte is released from the follicle/ovary.
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Female Anatomy sdfsdfsdf
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Menstruation 4.Luteal Phase Final preparation of endometrium to
receive the fertilized ovum LH stimulates development of the Corpus
Luteum. causes progesterone levels to increase.
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Menstruation
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4.Luteal Phase Final preparation of endometrium to receive the
fertilized ovum LH stimulates development of the Corpus Luteum.
causes progesterone levels to increase. Estrogen and progesterone
inhibit GnRH, thereby decreasing LH and FSH levels. This low level
of hormones initiates the flow phase.
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Menstruation
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Menopause The end of a womans reproductive years Between ages
of 45 55 Ovaries no longer respond to FSH & LH from AP Ovaries
do not produce estrogen or progesterone Marked by circulatory
irregularities (hot flashes), dizziness, insomnia, sleepiness,
depression Hormone replacement therapy may help.