Sexual Reproduction in Humans

Definition

Sexual reproduction is the process where two parent organisms produce offspring through the combination of their genetic materials.
This results in the offspring having genetic material from both parents, making them genetically unique.

The process begins with meiosis, a type of cell division that produces four genetically distinct sex cells, or gametes.
In humans, the male gamete (sperm) is produced in the testes, while the female gamete (egg or ovum) is produced in the ovaries.
The process continues with fertilisation - the fusion of male and female gametes to form a zygote.
The zygote undergoes cell division, developing into an embryo, which further develops into a fetus, eventually resulting in a new individual.

In females, the menstrual cycle is a routine process that prepares the body for reproduction.
The cycle is approximately 28 days long and is marked by the release of an egg during ovulation.
Key hormones control the menstrual cycle, including follicle-stimulating hormone (FSH), luteinising hormone (LH), oestrogen, and progesterone.

If fertilisation occurs, the zygote implants into the uterus, beginning pregnancy.
The placenta develops to supply the growing fetus with nutrients and oxygen while removing waste.
The fetus develops and grows in the uterus for about 40 weeks.
Childbirth typically occurs through a process known as labour, which involves strong contractions of the uterus to facilitate birth.

There is a greater genetic diversity among offspring, which can make populations more resilient against changes in the environment and disease.
This method of reproduction can lead to the evolution of the species through natural selection, as favourable traits can become more common over time.

It typically consumes more energy and resources than asexual reproduction, as finding a mate and the processes of meiosis and fertilisation are complex.
The genetic diversity it creates can lead to traits that have a negative impact on an individual’s survival or reproduction.
Offspring do not inherit all of their parents’ adaptations, which can be disadvantageous if the parents are particularly well adapted to their environment.