Sexual reproduction is defined as
a process involving the fusion of nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other
Fertilization is defined as the fusion of gamete nuclei, and as each gamete comes from a different parent, there is variation in the offspring
Background knowledge
Sex cells which are produced by the parent Organism are called gametes (examples of gametes are egg and sperms cells)
the nuclear fusion of the egg and sperm gametes is called fertilization
the byproduct of fertilization forms a new cell called a zygote
Gametes differ from ordinary cells because they only contain half of the chromosomes, as usual, this is so that when fertilization takes place the correct
number of chromosomes(46chromosones) will be obtained (the cell formed will be a diploid cell)
Gametes are often referred to as haploid cells (23 chromosomes)
THE MALE REPRODUCTIVE SYSTEM
The male gamete sperm are formed in the two testes (testis singular) they are present outside the body in the two sacks of the scrotum
Scrotum: holds testicles (helps in providing support)
Testes have many coiled tubes which produce sperm) and the cells between tubes produce testosterone.
The sperm duct is a tube that carries the sperm away from each of the testis
The sperm duct from the testes joins the urethra (carries semen from the sperm duct to the tip of the penis)
The prostate gland is located below the urethra
The prostate gland makes seminal fluid, a fluid which allows the sperm to swim in
The female reproductive system
The female gametes are called eggs and they are made in the ovaries.
Going away from the ovaries are the oviducts, also known as Fallopian tubes.
Oviducts have a funnel-shaped opening which helps in leading the ovum (single-celled egg) down to the uterus
Uterus also known as the womb is where the fetus grows for 9 months (during pregnancy)
Below the uterus, there is a narrow opening guarded by muscles it is called the cervix.
The cervix is also referred to as the neck of the uterus and is moist due to mucus secreted.
The vagina is located below the cervix as a moist tube of muscle which is flexible.
The vagina receives the penis during intercourse, and way out for the baby at birth.
Egg Production
Eggs are formed inside a girl’s ovaries before she is born
At birth, she will already have thousands of partly developed eggs inside her ovaries
When the girl reaches puberty some of these eggs will begin to mature (usually only one develops at a time)
When it is matured and the egg cell bursts out of the ovary and into the funnel at the end of the oviduct
This process is called ovulation and it occurs once a month in humans.
Sperm Production
Testis contains thousands of narrow tubes or tubules
Sperm cells are produced in the cell walls of the tubules which divide by meiosis
Sperm are produced from puberty onwards
Sperm production is sensitive to heat if they get too hot the tubules will not develop into sperm
That is why the testes are located outside the body where the environment is cooler and safe from the body heat which would be present inside the body
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Fertilisation and development
Millions of sperm cells venture down the sperm duct as a man ejaculates (also known as the vas deferens)
In the semen, the sperm are suspended (a fluid secreted by the prostate gland)
The urethra accepts the semen as it exits.
Semen is ejaculated into the female's vagina during sexual contact, proximal to the cervix.
The sperm cells then move through the mucus plug in the cervix, following a chemical path, to enter the uterus (the womb)
After that, the sperm cells enter the oviducts.
Fertilization can happen in the oviduct if a sperm cell and an egg cell encounter one another.
Most commonly, this transpires 1-2 days after the female has ovulated (released an egg cell from one of her ovaries into an oviduct)
The fusing of the nuclei from a male gamete (sperm cell) and a female gamete is known as fertilisation (egg cell)
To get through the egg cell membrane during fertilisation, the head of the sperm cell releases enzymes that digest a hole in the protective outer layer of the
egg cell.
To ensure that just one sperm cell can fertilise the egg cell, the egg cell instantly produces a thick coating of material that blocks any further sperm cells
from entering.
A zygote is created when the male and female gametes combine (fertilised egg cells)
The mother and father each contributed half of the zygote's 46 chromosomes, which are divided into 23 pairs.
The zygote undergoes mitosis to split into two new cells, which continue to divide until an embryo is created a few days later.
As cells continue to divide, many of the newly created cells eventually specialise to carry out specific tasks and create all of the bodily tissues of the
progeny.
further information on fertilisation and development
The zygote moves toward the uterus after fertilisation in the oviduct, which typically takes approximately 3 days. During this time, the zygote will split
multiple times to create a ball of cells called an embryo.
The embryo continues to grow and develop until it enters the uterus, where it implants itself in the thick uterine lining (a procedure known as
implantation).
Where the embryo is connected, a placenta develops.
An organ called the placenta makes sure that nutrients may be transferred between the mother's blood and the blood of the developing embryo.
The placenta receives blood from the embryo through the umbilical cord, which allows for the exchange of nutrients and the disposal of waste items.
In the uterus, the embryo develops during the following nine months.
The gestational period is referred to as this.
Within the first 12 weeks, major organ development occurs, and during this timeframe, the embryo obtains nutrients from the mother by diffusion through
the uterine lining.
When all the organs are present and the placenta is fully matured, the embryo is then referred to be a fetus
The fetus uses the remaining gestational period to grow larger
The mother's blood provides the foetus throughout pregnancy with all the glucose, amino acids, fatty acids, water, oxygen, mineral ions, and vitamins it
needs for growth and development.
The mother's and foetus’s blood are nearby proximity in the placenta, yet they never mingle.
The umbilical cord serves as a conduit for the blood of the foetus to reach and leave the placenta.
Waste materials from the fetus' blood are also absorbed by the mother's blood in the placenta; for example, carbon dioxide and urea are taken out of the
foetus' blood so that they do not accumulate to harmful levels.
The majority of molecules migrate across the placenta via diffusion as a result of concentration gradients that vary.
Active transport may be necessary for some materials that need to be transported.
A vast surface area and a thin wall of the placenta allow for effective diffusion in this situation.
Toxins and pathogens are kept out of the fetus's blood by the placenta, which serves as a barrier.
Pregnant women are recommended not to smoke during pregnancy since certain molecules, like nicotine, can cross the placenta and not all toxic or
harmful organisms, such as viruses like rubella, are prevented from doing so (this typically relies on the size of the molecule).
Once the infant is delivered, the umbilical cord is severed.
There are only two blood vessels and no nerves in this, thus it doesn't hurt.
It is tied off to stop the bleeding, and after a few days, it shrivels up and falls off, having left the belly button behind.
Shortly after birth, the placenta pushes itself out of the uterus due to contractions in the muscular uterine wall.
The term "afterbirth" refers to this.
SEXUALLY TRANSMITTED DISEASES
Venereal infections, sometimes called STDs (sexually transmitted diseases), are contagious illnesses that spread through sexual contact. Infections of the
reproductive tract are another name for it (RTI). Among the most well-known STDs include AIDS, Gonorrhea, syphilis, genital herpes and warts,
chlamydiosis, and hepatitis B. Different strains of bacteria, viruses, and parasites have all made their contributions. The majority of these illnesses progress
symptomless, raising the risk factors, particularly in women. Infertility, pelvic inflammatory disease (PID), abortions, ectopic pregnancies, and in the worst
cases, it might even result in cancer of the reproductive tract, are risk factors. The indications and symptoms of STDs include unusual vaginal secretions,
genital ulcers, tumours, itching, and more.
The term "sexually transmitted diseases" refers to all illnesses that spread through sexual contact. However, not all STDs are transmitted through sexual
activity; some can also spread through non-sexual contact. Transfusions of infected blood and tissue, nursing, sharing of needles, etc. are examples of noncontact mechanisms. STDs like AIDS can be transmitted from the mother to her kid either during childbirth or via nursing after the baby is born. Therefore,
before it blows out, careful diagnosis and treatment are required. Every STD has a treatment, but hepatitis B, genital herpes, and HIV infections stand out
from the rest of the list, according to medical field researchers. They are still unsure of these illnesses.
PREVENTION OF SEXUALLY TRANSMITTED DISEASES
Despite modern technology, STDs continue to pose a serious threat to the country. We frequently see advertising on television for various programmes
advocating responsible sexual behaviour and raising awareness of various STDs (STDs). The goal of all these initiatives by the government and nongovernmental groups was to create a society that was healthy for reproduction.
To stop additional waves, there has to be general knowledge about STDs. One of the measures the government has taken to educate teenagers about safe
sexual activities is the implementation of sex education. Providing appropriate medical facilities is crucial in addition to raising awareness and educating
people about STD issues.
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Avoid unprotected sex
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Avoid sexual contact with multiple partners
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Consult a qualified doctor for diagnosis and treatment.