Explain physiology of conception.

Conception, the process of fertilization leading to the formation of a new organism, begins with the fusion of a sperm cell from the male reproductive system with an egg cell (oocyte) from the female reproductive system. This typically occurs in the fallopian tube after ovulation.

During sexual intercourse, millions of sperm are ejaculated into the female reproductive tract. These sperm travel through the cervix, uterus, and into the fallopian tube, where they encounter the egg. Sperm cells undergo capacitation, a process that enables them to penetrate the protective layers surrounding the egg.

Once a sperm successfully penetrates the outer layer of the egg (the zona pellucida), it releases enzymes that allow it to fuse with the egg's plasma membrane. This fusion triggers a series of biochemical reactions within the egg, including the completion of meiosis, which results in the formation of a zygote.

The zygote, now a fertilized egg, begins to divide rapidly through mitosis as it travels down the fallopian tube towards the uterus. Along the way, it forms a blastocyst, a hollow ball of cells. The blastocyst implants itself into the thickened lining of the uterus (endometrium), initiating pregnancy.

The process of conception is a complex interplay of physiological events that require precise timing, coordination, and functionality of both male and female reproductive systems. It culminates in the formation of a new life, marking the beginning of pregnancy.