Reproduction in Human Being
Human beings show sexual reproduction. Male parent produces male gametes called
sperms. Female parent produces female gametes called ova. Sperms have tail and are
therefore, motile. They are produced in large numbers in the testes. Ovum is bigger, non-
motile and only one ovary produces one ovum in one month. There is no food stored in the
sperms whereas ova contain stored food. Both the gametes are microscopic unicellular
and have half the number of chromosomes as compared to the body cells.
PUBERTY
Human beings become reproductively active from the onset of puberty. Puberty is the
period during adolescence when the rate of general body growth begins to slow down
and reproductive tissues begin to mature. Onset of puberty in human males is between
11 to 13 yrs. of age, while in human females is between 10 to 12 yrs. of age.
Secondary Sexual Characters
Puberty is associated with many physical, mental, emotional and psychological changes in
boys and girls which occur slowly over a period of time. These are called secondary sexual
characters.
CHANGES COMMON TO BOTH GIRLS AND BOYS
thick dark hair starts growing in new parts such as arm pits and genital area
between the thighs.
Thinner hair appears on legs, arms and face.
Skin becomes oily and pimples may appear on the face.
Individuals become more conscious of their bodies and become more independent.
SPECIFIC IN BOYS
beard and moustache start appearing
Voice begins to crack
Reproductive organs develop and start producing releasing sperms.
Penis occasionally gets enlarged or erect either in daydreams or at night.
SPECIFIC IN GIRLS
Breast size begins to increase
Skin of the nipples darkens
Menstruation starts.
Male Reproductive System:
1 pair of testes
A system of ducts
Epididymis
Vas deferens or the sperm duct
Urethra
A system of glands
Seminal vesicles
Prostate gland
Cowper’s gland
A sexual organ called a penis.
TESTES
One pair of testes are present in a bag-like structure called scrotum which lies outside the
abdominal cavity; hence they are extra abdominal in position. This is so because the
testes have to be maintained at 1–3-degree lesser temperature than the body in order to
produce functional sperms.
Functions
To produce male gametes the sperms.
To produce a male reproductive hormone called testosterone which is
responsible for producing sperms as well as secondary sexual characteristics in
males.
EPIDIDYMIS
Attached to each testis is a highly coiled tube called epididymis. The sperms are stored
here and they mature in the epididymis. Each epididymis leads into the sperm duct or the
vas-deferens.
SPERM DUCT OR THE VAS-DEFERENS
Vas-deferens rises up and enters into the abdominal cavity. It unites with the duct coming
from the urinary bladder to form a common duct called URETHRA which passes through
the penis and opens to the outside. Along the way the ducts of the three glands also open
and pour their secretions into the vas deferens.
Function
It is meant for the passage of the sperms in the male body.
GLANDS
They produce different secretions which provide nutrition and medium for locomotion to
the sperms.
The secretions of the three glands along with the sperms is known as semen.
Penis
It is the organ which is used to introduce semen into the female body. It is richly supplied
with blood vessels.
Female Reproductive System:
1 pair of ovaries
1 pair of fallopian tubes or oviducts
A uterus/womb
A vagina/birth canal.
OVARY
Each ovary is almond shaped and present inside the abdominal cavity. At the time of birth
each girl child already contains thousands of immature ova. These ova start maturing only
from the time of puberty. Only one ovum is produced by one ovary in one month and each
ovary releases an ovum in alternate months. The release of an ovum from the ovary into
the abdominal cavity is known as ovulation.
Functions of ovary
To produce and release ova
To produce female reproductive hormones: estrogen and progesterone.
FALLOPIAN TUBES OR OVIDUCTS
There are two fallopian tubes. The end lying close to the ovary has finger like structures
called fimbriae. The two fallopian tubes unite to form an elastic bag like structure called
uterus.
Function
It is the site of fertilization btw the male and the female gametes & formation of
the zygote.
The inner lining of the uterus is richly supplied with blood vessels & is known as
endometrium.
The narrow end of the uterus is called cervix.
UTERUS
The embryo formed in the fallopian tube comes down and gets attached to the
endometrium (implantation) and develops for the next nine months till the baby is
delivered.
VAGINA
The uterus opens into the vagina through the cervix. The vagina is a muscular tube
through which the baby is delivered at the end of nine months. It also serves as the
canal for receiving the semen at the time of copulation.
The semen is discharged into the vaginal tract during copulation. The sperms travel
upwards and reach the fallopian tube where one sperm fuses with the ovum to form the
zygote. The zygote divides and redivides as it descends into the uterus and the embryo
gets implanted in the endometrium. The endometrium thickens so as to receive the
embryo.
EMBRYO
The embryo gets nutrition from the mother’s blood with the help of a special tissue
called placenta, which is a disk-like structure embedded in the uterine wall.
It contains finger-like villi on the embryo side, while on the mother’s side blood spaces
surround the villi. Villi provides a large surface area for glucose and oxygen to pass
from the mother to the developing embryo and the wastes to pass from the embryo to
the mother through the placenta.
When the embryo starts resembling a human is formed, it is termed as a foetus. The
foetus continues to develop inside the uterus for almost nine months after which the
baby is delivered as a result of rhythmic contractions of the uterine muscles.
Menstruation
It is the loss of blood, mucous along with the unfertilized ovum and the ruptured cells and
tissues of the endometrium through the vagina of the female. It is a 28-day cycle which
occurs in every reproductively active female (from puberty). The flow of blood continues
for 2 to 8 days. If the ovum does not get fertilized, then the endometrium starts sloughing
off and there is loss of blood and mucous through the vagina. In case the ovum gets
fertilized, then the endometrium becomes thick and spongy for nourishing the embryo and
hence menstruation does not occur. A lady with a developing embryo in her womb is
termed as pregnant. The beginning of menstruation at puberty is known as menarche. The
stoppage of menstruation when the woman is 45-55 yrs. of age is called menopause.
Sexually transmitted diseases [STD]
A number of diseases occur as a result of sexual intercourse if one of the partners is
infected. These are known as sexually transmitted diseases (STD’s). They can be caused
by bacteria for example; syphilis, gonorrhoea; or caused by a virus for example; HIV-AIDS,
warts etc. The transmission of these diseases can be avoided by wearing a condom during
the sexual act.
Birth control measures
Mechanical methods:
i. Use of condoms: Condoms are thin rubber tubes worn over the penis before sexual
intercourse. The semen gets collected in this and is not discharged into the
vagina.
ii. Diaphragm: It is a thin rubber fixed over a flexible metal ring which is fitted over
the cervix in a woman’s body by a doctor.
iii. Copper or loop: It is inserted in the uterus and its insertion causes certain secretion
which prevents the implantation of the embryo in the uterine wall.
Both methods (ii) and (iii) cause side effects.
Chemical methods
Oral contraceptive pills: These are hormonal pills which prevent ovulation but
do not stop menstruation.
(Side effect-hormonal imbalance)
Surgical methods
Surgical methods of creating blocks.
Medical termination of pregnancy (MTP) or abortions is carried out to eliminate
the developing embryo. This practice can, however, be misused to carry out
female foeticide which involves the killing of the female foetus. It should be
avoided at all cost as it disturbs the male-female ratio in a population.
(Side effect-infection in surgery)
