2. INDEX
1. The Reproductive Process in Human Beings
2. The Male Reproductive System
3. The Female Reproductive System
4. The Ovarian and Menstrual Cycle
5. Fertilisation, gestation and birth
6. Assisted reproduction
7. Contraception
8. Sexually transmitted diseases
5. Sexual characteristics:
• Primary sexual characteristics characteristics present at birth
(female/male genitalia)
• Secondary sexual characteristics characteristics which appear
with maturity. These changes occur at a very specific age,
called puberty.
6. Reproductive life in humans
In humans, reproductive and sexual life start during puberty.
A. Puberty
Puberty starts when boys start to produce sperm and become capable of ejaculation,
and when girls have their first period. Both of them take place as a result of increased
levels of pituitary hormones (FSH and LH) which stimulate gamete production.
http://www.cyh.com/HealthTopics/HealthTopicDetailsKids.aspx?p=335&np=289&id=1774 more information
7. Changes during puberty in girls
• the genitals get bigger
• breasts develop and the hips get wider
• hair grows on the pubis and under the arms
• the sebaceous glands start to secrete more sebum
• menarche (first period)
• the amount of body fat increases
8. Changes during puberty in boys
• the genitals get bigger
• the shoulders widen and the pelvis narrows
• body hear starts to grow
• the larynx and vocal cords grow, resulting in a lower voice
• the sebaceous glands start to secrete more sebum
• muscle mass increases
9. Some Mental Changes During Puberty
• Boys and girls start to want more freedom and independence
• They feel more self-sufficient
• They feel that most people around them do not understand them
•They want to belong to a group of people of their own age
• Their behaviour changes quickly from passiveness and a lack of interest to non-
conformism, rebellion and even violence. It can result in communication problems
both at home and at school.
10. B. The end of reproductive life
Men produce sperm throughout almost their whole life, although the quantity and
quality of these gametes decrease gradually after 50 years of age. It is caused
by a decrease in testosterone levels and it is called andropause.
Women are born with all of the immature eggs that they will ever have. However,
they stop ovulating, and therefore menstruating at a certain point in life (between
45-50 years of age). It is caused by a decrease in estrogens and progesterone
levels. It is called menopause.
11. 2. The Male Reproductive System
Cowper’s glands
12. Parts of the male reproductive system
Testicles Located outside the abdominal cavity, inside a skin sac called
scrotum. Testicles contain many seminiferous tubules (containing the cells
which produce sperm) and cells producing male sex hormones.
Cowper’s glands: secrete a lubricant that facilitates sexual intercourse.
Other glands they produce susbstances that mix with sperm to produce a fluid
called semen:
• Seminal vesicles: they produce nutrients for the sperm cells
• Prostate: secretes substances that protect sperm
Cowper’s glands
13. Reproductive ducts:
• Epididymis tubules where sperm matures
• Vas deferens it conects epididymis with urethra
• Urethra it carries the semen outside of the body. Common duct to the excretor
system
Penis: Organ that men use to deposit semen inside a woman’s body during
sexual intercourse. It contains two spongy masses of erectile tissue.
The penis ends at the glans (glande), surrounded by some skin called prepuce
(prepucio)
15. Parts of the female reproductive system
The ovaries They are found in the abdominal cavity. Inside them, each month
an ovum matures and is then released. They also produce female sex hormones.
16. Reproductive ducts:
• Fallopian tubes: They collect the mature eggs released by the ovaries. Fertilisation
normally takes place here.
• Uterus or womb: Gestation occurs here. The wall of the uterus has a
thick muscular layer (the myometrium) lined with a mucous membrane (endometrium).
• Vagina: Elastic tract which conects the uterum with the outside. Semen is deposited
in the vagina during sexual intercourse. To both side of the vagina are the Bartholin
glands, which produce lubricants.
• Vulva: External female sex organ, made of labia minora, labia majora and the clitoris
(a small, especially sensitive protuberance).
17. 4. The ovarian and menstrual cycle
The ovarian cycle
After puberty, oogenesis takes place regularly in women, approximately every 28 days.
One egg cell matures and is then released. Phases:
1. Follicular phase FSH (follicle stimulating hormone) stimulates the development of
one follicle in the ovary. It lasts around 14 days.
2. Ovulation LH (luteinising hormone)
stimulates the release of an egg by the
ovary. The body temperature increases.
3. Luteal phase Once the egg has
been released, the corresponding area
in the ovary transforms into the corpus
luteum, which secretes progesterone.
After 10-12 days, the corpus luteum
decays, initiation the start of a new
cycle.
18. The menstrual cycle
It is a series of periodical changes that occur in women’s sex organs.
It prepares the uterus for the implantaion of an embryo. However, the cycle
happens even if an egg has not been fertilised. Phases:
1. Proliferative phase the endometrium is built up. It lasts around 11 days.
2. Luteal phase the endometrium reaches its maximum thickness and prepares
to receive and give nutrients to an embryo. It last around 12 days. If there is an
embryo, the luteal phase continues.
3. Menstruation (or period) Only happens when there is no embryo.
The endometrium comes off, and is then expelled from the body along with some
blood. A period usually lasts 4-5 days.
19. The menstrual cycle and the ovarian cycle are controlled by hormones, which
are produced by the adenohypophysys (FSH and LH) and
by the ovaries (estrogen and progesterone)
24. 5.1 Fertilisation
It takes places inside the female reproductive system, usually in the Fallopian tubes.
The spermatozoids are introduced into the vagina during coitus, when ejaculation occurs.
Spermatozoa only live for 5 days and an ovum only lives for 48 hours.
If a spermatozoid finds an ovum:
1. The spermatozoid secretes a substance that breaks down the ovum’s outer membrane.
2. The two gametes recognise each other.
3. The sperm enters the ovum.
4. The nuclei of the two gametes join together. This is the fertilisation. The new cell
formed is called zygote.
5. A barrier around the zygote is formed,
preventing the access of any other sperm.
25.
26. The genetic information in the 23 paternal chromosomes transported
by the spermatozoid is mixed with the maternal genetic information
contained in the 23 chromosomes transported by the ovum.
This new cell is the zygote, which contains 46 cromosomes.
After 24 hours this cell starts dividing, and it is called embryo.
zygote
embryo
27. 5.2 Pregnancy (human gestation)
It is the period of time between fertilisation and birth. It lasts around 9 months.
28. The zygote divides many times during its way to the uterus. The structure is known
as the embryo, which becomes implanted in the uterus in 7 days after fertilisation.
29. About 2 - 3 months after fertilisation, the
embryo becomes a foetus. A foetus
looks like a baby. It continues growing
and developing in the uterus until birth.
The embryo and the foetus develop inside a membrane called amnion,
which is submerged in a liquid called amniotic fluid.
foetus
30. The foetus receives the nutrition it needs via the placenta, an organ that
develops around the 60th day of gestation. It is connected to the foetus
through the umbilical cord.
Placenta
33. 5.3 Labour and birth
In the eighth month of pregnancy, the foetus turns around in
the uterus so that the head is pointing downwards.
The baby is ready to be born in the nineth month of gestation.
The labour takes place in three phases:
Dilation of the uterine neck: 3-12 hours. The cervix dilates and and there are
contractions, which cause the rupture of the bag of amniotic fluid.
The uterine neck or cervix is the part of the female reproductive system
that lies between the body uterus and vagina
34. Expulsion of the foetus: The contractions of the walls of the uterus push
The foetus along the vagina to the exterior. The foetus comes out head first.
Expulsion of the placenta: After the baby is born and the umbilical cord is cut,
the uterus undergoes further contractions to expel the placenta.
36. 6. Assisted reproduction
Infertility refers to the inability to have children using natural methods. It can
occur in both men and women, and there are many different causes. Examples:
Low sperm count
Sperm incompatible with cervical mucus
Problems with ovulation
Uterine abnormalities which avoid implantation
Methods
Artificial insemination: artificial introduction of the semen in the uterus
In vitro fertilisation: to get egg from the woman and fertilise them outside
her body. Then, the embryos are implanted in the uterus.
39. 7. Contraception
Contraceptive methods can be used by couples who want to have sexual
intercourse without the woman becoming pregnant.
Natural methods:
• Rhythm method or Ogino-Knaus method: It consists of observing the woman’s
menstrual cycle for several months and calculating the days when ovulation is
likely to take place. Intercourse can then be avoided during that time.
It is not a safe method because it is difficult to calculate the exact moment
of the ovulation and it does not protect against STDs.
40. • Coitus interruptus: During sexual intercourse, the man take his penis
out of the woman’s vagina just before he ejaculates. Not reliable method
because previouse secretions can contain sperm.
Barrier methods:
• Condoms, diaphragm and intrauterine device: they prevent sperm from reaching
the egg.
- Condom: Thin covering made of latex, that is rolled over an erect penis .
Very effective (90-98%). It protects against STDs.
41. -Diaphragm: latex dome which forms a barrier to stop sperm from reaching the cervix.
It is always used with spermicidal cream. It does not avoid STDs.
-Intrauterine device (DIU): small, plastic,
T-shaped device that is inserted into the
uterus by a doctor. It can stay there for years.
It does not protect against STDs.
42. Chemical methods: they contain hormones.
• Emergency contraceptive pills or morning-after pill: It can avoid the pregnancy
after a sexual intercourse without protection, avoiding the implantation of a possible
embryo. It is only an emergency method because it contains high levels of hormones
and it does not protect against STDs.
• Contraceptive pill: It avoids ovulation, but allowing menstruation. High
effectiveness. Doctor prescription necessary. It does not protect against STDs.
43. Surgical methods: Surgeries that are used to permanently prevent fertilisation.
• Tubal ligation (for women): Fallopian tubes are cut, in order to avoid eggs go
through.
• Vasectomy (for men): Vas deferens are cut, so that the semen does not contain
sperm.
44. 8. Sexually transmitted diseases (STDs)
They are diseases that can be transmitted by sexual contact. They can be caused
by viruses, bacteria, funghi or protozoa. Some of them can be transmitted to the baby
of a pregnant woman through the placenta or during the labour.
- Syphilis (bacteria)
- Gonorrhoea (bacteria)
- Candidiasis
- Genital herpes (virus)
- Hepatitis B (virus)
- HIV (Human Immunodeficiency Virus)
- HPV (Human Papilloma Virus)
45. STD Microorganism Main Symptoms
Syphilis Bacteria Ulcers on the genitalia,
called chancres. It
affects to the nervous
system.
Gonorrhoea Bacteria Painful urination and
inflammation of the
genitalia.
Candidiasis Fungus Irritation of the vagina
an inflammation of the
glans.
Genital herpes Virus Sores on the genitals
and anus.
Hepatitis B Virus Inflammation of the
liver.
AIDS HIV virus Serious weakening of
the immune system.
Human Papilloma
Virus
Virus It could cause cervix
cancer.
chancres
Neisseria gonorrheae
