Join us for an introduction to understanding human reproduction! From menstruation to pregnancy, learn about how our bodies work together to create new life. We cover key biological processes involved, discuss common health issues related to the female reproductive system, provide tips on maintaining reproductive health, and address any burning questions you have had regarding sex education. By the end of this presentation, viewers should feel better informed and empowered around these important topics. Let's dive into the fascinating world of reproductive science!
2. External genitalia
A. Penis
1. Structure and function of the penis: The penis is composed of three main parts: the
root, the shaft, and the glans. It is made up of erectile tissue that allows it to
become rigid and erect during sexual arousal. The urethra, which carries both urine
and semen out of the body, runs through the center of the penis.
2. Erectile tissue and mechanism of erection: The erectile tissue in the penis is made
up of two spongy tissue chambers called the corpora cavernosa and a single
chamber called the corpus spongiosum. During sexual arousal, these chambers fill
with blood, causing the penis to become erect.
3. Role of the penis in reproduction: The penis is the male sex organ responsible for
delivering sperm into the female reproductive tract during sexual intercourse.
4. Scrotum
Structure and function of the scrotum: The
scrotum is a sac of skin and muscle that
holds the testes. It is located outside of the
body and has a slightly lower temperature
than the rest of the body, which is essential
for optimal sperm production.
Role of the scrotum in regulating
temperature for optimal sperm production:
The scrotum contracts and relaxes in
response to changes in temperature,
bringing the testes closer to or farther away
from the body to maintain an optimal
temperature for sperm production.
5. II. Internal
genitalia
A. Testes
Structure and function of the testes: The testes are the
male gonads responsible for producing sperm and
testosterone. They are oval-shaped organs located in the
scrotum and are composed of seminiferous tubules and
interstitial tissue.
Leydig cells and testosterone production: Leydig cells,
located in the interstitial tissue of the testes, produce
testosterone, the male sex hormone responsible for the
development of male reproductive organs and secondary
sex characteristics.
Sertoli cells and spermatogenesis: Sertoli cells, located in
the seminiferous tubules of the testes, support and
nourish developing sperm cells during spermatogenesis,
the process of sperm cell production.
6. Epididymis
Structure and function of the epididymis:
The epididymis is a coiled tube located on
the surface of each testicle. It is responsible
for the maturation and storage of sperm.
Maturation and storage of sperm: During
their journey through the epididymis, sperm
undergo a process of maturation, becoming
more motile and gaining the ability to fertilize
an egg. The epididymis also serves as a
storage site for mature sperm until they are
ready to be ejaculated.
7. Vas deferens
Structure and function of the vas
deferens: The vas deferens is a muscular
tube that connects the epididymis to the
ejaculatory ducts. It transports mature
sperm from the epididymis to the
ejaculatory ducts, where they mix with
seminal fluid to form semen.
Role in transporting sperm to the
ejaculatory ducts: The vas deferens
contracts during ejaculation, propelling
sperm and seminal fluid through the
ejaculatory ducts and out of the penis.
8. Anatomy of the Female
Reproductive System
A. External genitalia
Vulva: The external female genitalia are
collectively referred to as the vulva, which
includes the mons pubis, labia majora, labia
minora, clitoris, vestibule, and vaginal opening.
Function of the vulva: The vulva serves as the
external entrance to the female reproductive
tract and plays a role in sexual stimulation.
9. Internal genitalia
Vagina: The vagina is a muscular tube that extends
from the vulva to the cervix. It serves as the site for
sexual intercourse and also serves as the birth canal
during delivery.
Cervix: The cervix is the lower part of the uterus that
protrudes into the vagina. It is composed of strong
muscles that help keep the baby in the uterus during
pregnancy and dilate during labor to allow the baby to
pass through.
Uterus: The uterus is a pear-shaped organ that sits in
the pelvis and is responsible for nourishing and
protecting a developing fetus during pregnancy.
Fallopian tubes: The fallopian tubes are a pair of
tubes that extend from the uterus and lead to the
ovaries. They serve as the site for fertilization of the
egg by sperm.
Ovaries: The ovaries are a pair of almond-shaped organs located on
either side of the uterus. They are responsible for producing and
releasing eggs for fertilization, as well as producing hormones such
as estrogen and progesterone.
10. Physiology of
Menstruation
Definition: The menstrual cycle is a series
of physiological changes that occur in the
female reproductive system, regulated by
the hypothalamus, pituitary gland, and
ovaries, and results in the shedding of
the uterine lining.
Duration: The menstrual cycle lasts
approximately 28 days, but can vary from
21-35 days in length.
11. Hormonal
regulation
Gonadotropin-releasing hormone (GnRH): GnRH is
produced by the hypothalamus and stimulates the
pituitary gland to release follicle-stimulating
hormone (FSH) and luteinizing hormone (LH).
Follicle-stimulating hormone (FSH): FSH stimulates
the growth and maturation of ovarian follicles.
Luteinizing hormone (LH): LH triggers ovulation, the
release of an egg from the ovary.
Estrogen: Estrogen is produced by the maturing
ovarian follicles and stimulates the thickening of the
uterine lining.
Progesterone: Progesterone is produced by the
corpus luteum after ovulation and further thickens
the uterine lining in preparation for implantation.
12. Phases of the
menstrual cycle
Menstrual phase: The menstrual phase is the shedding
of the uterine lining, which lasts approximately 3-7 days.
Proliferative phase: The proliferative phase is the growth
and thickening of the uterine lining, stimulated by
estrogen. It occurs approximately days 5-14 of the cycle.
Ovulatory phase: The ovulatory phase is the release of
an egg from the ovary, triggered by a surge in LH. It
occurs approximately day 14 of the cycle.
Luteal phase: The luteal phase is the maintenance and
further thickening of the uterine lining, stimulated by
progesterone. If implantation does not occur, the corpus
luteum disintegrates, progesterone levels decrease, and
the cycle begins anew.
13. Menstrual disorders
1.Amenorrhea: Amenorrhea is the absence of menstrual periods
and can be caused by hormonal imbalances, pregnancy,
menopause, or certain medications.
2.Dysmenorrhea: Dysmenorrhea is painful menstrual periods,
which can be caused by hormonal imbalances or certain medical
conditions.
3.Menorrhagia: Menorrhagia is abnormally heavy menstrual
bleeding, which can be caused by hormonal imbalances, fibroids,
or other medical conditions.
14. Spermatogenesis:
1.Spermatogenesis is the process by which male germ cells, or
sperm, are produced in the testes. This complex process
involves the development of haploid spermatozoa from diploid
germ cells through a series of mitotic and meiotic cell divisions,
differentiation, and maturation.
15. Process of spermatogenesis:
1.Hormonal regulation: At puberty, the hypothalamus releases GnRH, which
triggers the production of LH and FSH. These hormones act on the testes,
promoting spermatogenesis.
2.Primordial germ cells: These cells are already present in the testes, as they
migrated from the yolk sac during embryonic development. They have been
dormant until the onset of puberty and the hormonal regulation
3.Hormonal regulation (step 1) serves as the "trigger" that activates the
primordial germ cells (step 2) to start the spermatogenesis process. Once
puberty is reached and hormonal regulation takes place, the primordial germ
cells are stimulated to differentiate into spermatogonial stem cells, which will
further divide and differentiate to produce sperm cells.
16. Hormonal regulation
1.The hypothalamus releases gonadotropin-releasing hormone
(GnRH), which stimulates the anterior pituitary gland to produce
luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
2.LH stimulates Leydig cells in the testes to produce testosterone.
3.FSH stimulates Sertoli cells, which support and nourish
developing sperm cells and initiate the functional responses
needed for spermatogenesis.
17. Oogenesis
1.Oogenesis is the process by which female germ cells, or ova
(eggs), are produced in the ovaries. This complex process
involves the development of haploid ova from diploid germ cells
through a series of mitotic and meiotic cell divisions, growth, and
maturation.
18. Role of hormones in oogenesis
1.Primordial germ cells: These are the precursor cells that originate
in the yolk sac of the embryo and migrate to the developing
gonads. They give rise to oogonia in the female gonads
(ovaries).
19. Role of hormones.
1. Gonadotropin-releasing hormone (GnRH): Released by the hypothalamus, it stimulates the release of luteinizing hormone
(LH) and follicle-stimulating hormone (FSH) from the anterior pituitary gland.
2. Luteinizing hormone (LH): It triggers ovulation, which is the release of the secondary oocyte from the ovarian follicle. LH
also stimulates the development of the corpus luteum, a structure that produces progesterone.
3. Follicle-stimulating hormone (FSH): It stimulates the growth and maturation of ovarian follicles, which contain the
developing oocytes. FSH also triggers the production of estrogen by the follicle cells.
4. Estrogen: It promotes the development and maintenance of female secondary sexual characteristics and prepares the
endometrium (uterine lining) for implantation.
5. Progesterone: It is produced by the corpus luteum and is essential for maintaining pregnancy. Progesterone also helps
regulate the menstrual cycle and supports the endometrium for possible implantation of a fertilized ovum.
20. Pregnancy
1. Pregnancy is the period of time during which a fertilized egg (zygote)
develops into an embryo and subsequently a fetus within the uterus of a
female. This process ultimately results in the birth of a baby. A typical human
pregnancy lasts approximately 40 weeks or about 9 months and is divided
into three trimesters.
21. Role of hormones during pregnancy:
1. Human chorionic gonadotropin (hCG): This hormone is produced by the developing placenta soon
after fertilization. It maintains the corpus luteum, ensuring continued production of progesterone and
estrogen. hCG levels increase rapidly during early pregnancy and are used as an indicator in
pregnancy tests.
2. Progesterone: This hormone is initially produced by the corpus luteum and later by the placenta. It
supports the growth of the endometrium, preventing its shedding during menstruation. Progesterone
also relaxes the smooth muscles of the uterus, reducing the risk of premature contractions and helps
prepare the breasts for milk production.
3. Estrogen: Produced by the corpus luteum and the placenta, estrogen helps maintain the pregnancy
by promoting the growth of the uterus and the development of the placenta. It also supports the
development of the fetus and the mother's mammary glands in preparation for lactation.
22. Trimesters of pregnancy and key developments:
1. First trimester (Weeks 1-12): During this stage, the fertilized egg implants into the uterine lining, and the placenta begins
to form. The embryo's organs and structures start to develop, including the neural tube, heart, and limb buds. By the end
of the first trimester, the fetus has a recognizable human form with facial features, hands, feet, and the basic structure of
all vital organs.
2. Second trimester (Weeks 13-27): The fetus continues to grow rapidly, and its organs and systems mature. The mother
may begin to feel fetal movements (quickening) during this time. The fetus's skin is covered in a protective substance
called vernix caseosa. The genitals are formed, and the fetus's sex can usually be determined through ultrasound. By the
end of the second trimester, the fetus can hear, swallow, and has developed a sleep-wake cycle.
3. Third trimester (Weeks 28-40): The fetus continues to grow, and its organs mature further. The lungs develop, and the
fetus starts practicing breathing movements. The fetus gains weight and accumulates fat, which helps regulate body
temperature after birth. The brain develops rapidly, and the fetus becomes more responsive to external stimuli. In the final
weeks of pregnancy, the fetus typically moves into a head-down position, preparing for birth. Labor and delivery usually
occur during this trimester.
23. Parturition
Parturition is the process of childbirth, during which a baby is born,
and the placenta is expelled from the uterus. It involves a series of
coordinated events, including uterine contractions and changes in
the cervix, which facilitate the delivery of the baby and the
placenta.
24. Stages
1. Stage 1: Dilation of the cervix
2. This stage begins with the onset of regular contractions and ends when the cervix is fully dilated
(approximately 10 centimeters).
3. It is further divided into two phases: the latent phase and the active phase.
4. Latent phase: Contractions are mild and irregular, and the cervix begins to soften and dilate
slowly.
5. Active phase: Contractions become stronger, more regular, and closer together, and the cervix
dilates more rapidly.
6. During this stage, the amniotic sac may rupture ("water breaking"), releasing amniotic fluid.
7. Stage 2: Delivery of the baby
25. Continue .
1. This stage starts when the cervix is fully dilated and ends with the delivery of the baby.
2. The mother feels a strong urge to push during contractions, which helps move the baby
through the birth canal.
3. The baby's head crowns (becomes visible) as it passes through the vaginal opening, and
the rest of the body follows.
4. Once the baby is born, the umbilical cord is clamped and cut.
5. Stage 3: Delivery of the placenta
6. This stage begins after the baby is born and ends with the delivery of the placenta
(afterbirth).
7. The uterus continues to contract, causing the placenta to detach from the uterine wall and
be expelled through the vagina.
8. This stage usually takes 5-30 minutes but can be longer in some cases.
